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Java Programming Case Study Examples

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If you are an HR professional looking for talented Java programmers, then you are in the right place. This article will provide you with some great case study examples that showcase the skills and expertise of top Java programmers.

Importance of Case Studies for HR Professionals

Case studies are an essential tool for HR professionals when hiring top talent. They provide a deeper understanding of a candidate’s skills, knowledge, and experience, which is not always possible through resumes or interviews. By reviewing case studies, HR professionals can evaluate a candidate’s ability to solve complex problems and develop innovative solutions.

Here are some excellent case study examples that demonstrate the skills and expertise of top Java programmers:

• Google Maps : Google Maps is one of the most popular navigation applications in the world. It is built using Java and provides real-time traffic updates, street views, and satellite imagery. Google Maps is an excellent example of how Java programming can be used to develop complex and innovative solutions.
• Amazon : Amazon is the world’s largest online retailer, and its website is built using Java. The website handles millions of transactions every day, and its success is a testament to the reliability and scalability of Java programming.
• Netflix : Netflix is a streaming platform that delivers movies and TV shows to millions of users worldwide. It uses Java programming to create personalized recommendations, manage user profiles, and optimize streaming quality.

Why Choose Algobash?

At Algobash, we specialize in connecting HR professionals with top Java programmers. Our platform features a comprehensive database of talented programmers who have been rigorously tested and vetted. By using Algobash, you can save time and money while finding the perfect candidate for your organization.

Benefits of Using Automated Interview for Companies

Best platform for ai interview in indonesia, 10 interview questions and answers that job seekers should keep in mind.

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13.5: Case Study- Designing a Basic GUI

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• Ralph Morelli & Ralph Wade
• Trinity College

What elements make up a basic user interface? If you think about all of the various interfaces you’ve encountered—and don’t just limit yourself to computers—they all have the following elements:

Some way to provide help/guidance to the user.

Some way to allow input of information.

Some way to allow output of information.

Some way to control the interaction between the user and the device.

Think about the interface on a beverage machine. Printed text on the machine will tell you what choices you have, where to put your money, and what to do if something goes wrong. The coin slot is used to input money. There’s often some kind of display to tell you how much money you’ve inserted. And there’s usually a bunch of buttons and levers that let you control the interaction with the machine.

These same kinds of elements make up the basic computer interface. Designing a Graphical User Interface is primarily a process of choosing components that can effectively perform the tasks of input, output, control, and guidance.

In the programs we designed in the earlier chapters, we used two different kinds of interfaces. In the command-line interface, we used printed prompts to inform the user, typed commands for data entry and user control, and printed output to report results. Our GUI interfaces used JLabel s to guide and prompt the user, JTextField s and JTextArea s as basic input and output devices, and either JButton s or JTextField s for user control.

Let’s begin by building a basic GUI in the form of a Java application. To keep the example as close as possible to the GUIs we’ve already used, we will build it out of the following Swing components: JLabel , JTextField , JTextArea , and JButton .

The Metric Converter Application

Suppose the coach of the cross-country team asks you to write a Java application that can be used to convert miles to kilometers. The program should let the user input a distance in miles, and the program should report the equivalent distance in kilometers.

Before we design the interface for this, let’s first define a MetricConverter class that can be used to perform the conversions (Fig. 13.9). For now at least, this class’s only task will be to convert miles to kilometers, for which it will use the formula that 1 kilometer equals 0.62 miles:

Note that the method takes a double as input and returns a double . Also, by declaring the method static , we make it a class method, so it can be invoked simply by

Choosing the Components

Let’s now design a GUI to handle the interaction with the user. First, let’s choose Swing components for each of the four interface tasks of input, output, control, and guidance. For each component, it might be useful to refer back to Figure [fig-swing2-guis] to note its location in the Swing hierarchy.

A JLabel is a display area for a short string of text, an image, or both. Its AWT counterpart, the Label , cannot display images. A does not react to input. Therefore, it is used primarily to display a graphic or small amounts of static text. It is perfectly suited to serve as a prompt, which is what we will use it for in this interface.

A JTextField is a component that allows the user to edit a single line of text. It is identical to its AWT counterpart, the TextField . By using its getText() and setText() methods, a JTextField can be used for either input or output, or both. For this problem, we’ll use it to perform the interface’s input task.

A JTextArea is a multiline text area that can be used for either input or output. It is almost identical to the AWT TextArea component. One difference, however, is that a JTextArea does not contain scrollbars by default. For this program, we’ll use the JTextArea for displaying the results of conversions. Because it is used solely for output in this program, we’ll make it uneditable to prevent the user from typing in it.

Let’s use a JButton as our main control for this interface. By implementing the ActionListener interface we will handle the user’s action events.

Choosing the Top-Level Window

The next issue we must decide is what kind of top-level window to use for this interface. For applet interfaces, the top-level component would be a JApplet . For Java applications, you would typically use a JFrame as the top-level window. Both of these classes are subclasses of Container , so they are suitable for holding the components that make up the interface (Fig. [fig-swing1-guis] ).

Also, as noted earlier, JApplet s and JFrame s are both examples of heavyweight components, so they both have windows associated with them. To display a JFrame we just have to give it a size and make it visible. Because a frame runs as a stand-alone window, not within a browser context, it should also be able to exit the application when the user closes the frame.

Designing a Layout

The next step in designing the interface is deciding how to arrange the components so that they will be visually appealing and comprehensible, as well as easy to use.

Figure [fig-metricgui] shows a design for the layout. The largest component is the output text area, which occupies the center of the JFrame . The prompt, input text field, and control button are arranged in a row above the text area. This is a simple and straightforward layout.

Figure [fig-metricgui] also provides a containment hierarchy , also called a widget hierarchy , which shows the containment relationships among the various components. Although it might not seem so for this simple layout, the containment hierarchy plays an important role in showing how the various components are grouped in the interface. For this design, we have a relatively simple hierarchy, with only one level of containment. All of the components are contained directly in the JFrame .

Figure 13.11 shows the design of the Converter class, which extends the JFrame class and implements the ActionListener interface. As a JFrame subclass, a Converter can contain GUI components. As an implementor of the ActionListener interface, it also will be able to handle action events through the actionPerformed() method.

Figure [fig-converterclass] gives the implementation of the Converter class. Note the three packages that are imported. The first contains definitions of the Swing classes, and the other two contain definitions of AWT events and layout managers that are used in the program.

We have to do all initializing tasks in the constructor. First, we have to set the JFrame ’s layout to FlowLayout . A layout manager is the object that is responsible for sizing and arranging the components in a container so that the elements are organized in the best possible manner. A flow layout is the simplest arrangement: The components are arranged left to right in the window, wrapping around to the next “row” if necessary.

Second, note the statements used to set the layout and to add components directly to the JFrame . Instead of adding components directly to the JFrame , we must add them to its content pane:

A content pane is a JPanel that serves as the working area of the JFrame . It contains all of the frame’s components. Java will raise an exception if you attempt to add a component directly to a JFrame .

The JFrame and all the other top-level Swing windows have an internal structure made up of several distinct objects that can be manipulated by the program. Because of this structure, GUI elements can be organized into different layers within the window to create many types of sophisticated layouts. Also, one layer of the structure makes it possible to associate a menu with the frame.

Finally, note how the Converter frame is instantiated, made visible, and eventually exited in the application’s main() method:

It is necessary to set both the size and visibility of the frame, since these are not set by default. Because we are using a FlowLayout , it is especially important to give the frame an appropriate size. Failure to do so can cause the components to be arranged in a confusing way and might even cause some components to not appear in the window. These are limitations we will fix when we learn how to use some of the other layout managers.

Inner Classes and Adapter Classes

In this section we introduce two new language features, inner classes and adapter classes , which are used in the main() method shown above to handle the closing of the Converter application’s window when the program is exited:

This code segment provides a listener that listens for window closing events. When such an event occurs, it exits the application by calling System.exit() .

The syntax used here is an example of an anonymous inner class . An inner class is a class defined within another class. The syntax is somewhat ugly, because it places the class definition right where a reference to a window listener object would go. In effect what the code is doing is defining a subclass of WindowAdapter and creating an instance of it to serve as a listener for window closing events.

Anonymous inner classes provide a useful way of creating classes and objects on the fly to handle just this kind of listener task. The syntax used actually enables us to write one expression that both defines a class and creates an instance of it to listen for window closing events. The new subclass has local scope limited here to the main() method. It is anonymous, meaning we aren’t even giving it a name, so you can’t create other instances of it in the program. Note that the body of the class definition is placed right after the new keyword, which takes the place of the argument to the addWindowListener() method. For more details on the inner and anonymous classes, see Appendix F.

An adapter class is a wrapper class that implements trivial versions of the abstract methods that make up a particular interface. (Remember from Chapter 4 that a wrapper class contains methods for converting primitive data into objects and for converting data from one type to another.)

The WindowAdapter class implements the methods of the WindowListener interface. When you implement an interface, such as ActionListener , you must implement all the abstract methods defined in the interface. For ActionListener there’s just one method, the actionPerformed() method, so we can implement it as part of our applet or frame class. However, we want to use only one of the seven methods available in the WindowListener interface, the windowClosing() method, which is the method implemented in the anonymous inner class:

The WindowAdapter is defined simply as

Note that each method is given a trivial implementation (). To create a subclass of WindowAdapter , you must override at least one of its trivially implemented methods.

Another way to manage the application’s window closing event is to define a subclass of WindowAdapter :

Given this class, we can then place the following statement in Converter ’s main() method:

This is somewhat more familiar looking than the inner class construct. If you prefer this way of handling things, you can use this method in place of the inner classes here and in other examples.

GUI Design Critique

Figure 13.13 shows the converter interface. Although our basic GUI design satisfies the demands of input, output, control, and guidance, it has a few significant design flaws.

First, it forces the user to manually clear the input field after each conversion. Unless it is important that the user’s input value remain displayed until another value is entered, this is just an inconvenience to the user. In this case, the user’s input value is displayed along with the result in the JTextArea , so there’s no reason not to clear the input text field:

A second problem with our design is that it forces the user to switch between the keyboard (for input) and the mouse (for control). Experienced users will find this annoying. An easy way to fix this problem is to make both the JTextField and the JButton serve as controls. That way, to get the program to do the conversion, the user can just press the Enter key after typing a number into the text field.

To give the interface this type of control, we only need to add an ActionListener to the JTextField during the initialization step:

A JTextField generates an ActionEvent whenever the Enter key is pressed. We don’t even need to modify the actionPerformed() method, since both controls will generate the same action event. This will allow users who prefer the keyboard to use just the keyboard.

Given that the user can now interact with the interface with just the keyboard, a question arises over whether we should keep the button at all. In this case, it seems justifiable to keep both the button and the text field controls. Some users dislike typing and prefer to use the mouse. Also, having two independent sets of controls is a desirable form of redundancy. You see it frequently in menu-based systems that allow menu items to be selected either by mouse or by special control keys.

Another deficiency in the converter interface is that it doesn’t round off its result, leading sometimes to numbers with 20 or so digits. Develop Java code to fix this problem.

Give an example of desirable redundancy in automobile design.

Extending the Basic GUI: Button Array

Suppose the coach likes our program but complains that some of the folks in the office are terrible typists and would prefer not to have to use the keyboard at all. Is there some way we could modify the interface to accommodate these users?

This gets back to the point we were just making about incorporating redundancy into the interface. One way to satisfy this requirement would be to implement a numeric keypad for input, similar to a calculator keypad. Regular JButton s can be used as the keypad’s keys. As a user clicks keypad buttons, their face values—0 through 9—are inserted into the text field. The keypad will also need a button to clear the text field and one to serve as a decimal point.

This new feature will add 12 new JButton components to our interface. Instead of inserting them into the JFrame individually, it will be better to organize them into a separate panel and to insert the entire panel into the frame as a single unit. This will help reduce the complexity of the display, especially if the keypad buttons can be grouped together visually. Instead of having to deal with 16 separate components, the user will see the keypad as a single unit with a unified function. This is an example of the abstraction principle, similar to the way we break long strings of numbers (1-888-889-1999) into subgroups to make them easier to remember.

Figure [fig-metricgui2] shows the revised converter interface design. The containment hierarchy shows that the 12 keypad JButton s are contained within a JPanel . In the frame’s layout, the entire panel is inserted just after the text area.

Incorporating the keypad into the interface requires several changes in the program’s design. Because the keypad has such a clearly defined role, let’s make it into a separate object by defining a KeyPad class (Fig. 13.15). The KeyPad will be a subclass of JPanel and will handle its own ActionEvent s. As we saw in Chapter 4, a JPanel is a generic container. It is a subclass of Container via the JComponent class (Fig. [fig-swing2-guis] ). Its main purpose is to contain and organize components that appear together on an interface.

In this case, we will use a JPanel to hold the keypad buttons. As you might recall from Chapter 4, to add elements to a JPanel , you use the add() method, which is inherited from Container . (A JApplet is also a subclass of Container via the Panel class.)

As a subclass of JPanel , the KeyPad will take care of holding and organizing the JButton s in the visual display. We also need some way to organize and manage the 12 keypad buttons within the program’s memory. Clearly, this is a good job for an array. Actually, two arrays would be even better, one for the buttons and one for their labels:

The label array stores the strings that we will use as the buttons’ labels. The main advantage of the array is that we can use a loop to instantiate the buttons:

This code should be placed in the KeyPad() constructor. It begins by instantiating the array itself. It then uses a for loop, bounded by the size of the array, to instantiate each individual button and insert it into the array. Note how the loop variable here, k , plays a dual role. It serves as the index into both the button array ( buttons ) and the array of strings that serves as the buttons’ labels ( labels ). In that way the labels are assigned to the appropriate buttons. Note also how each button is assigned an ActionListener and added to the panel:

An important design issue for our KeyPad object concerns how it will interact with the Converter that contains it. When the user clicks a keypad button, the key’s label has to be displayed in the Converter ’s text area. But because the text area is private to the converter, the KeyPad does not have direct access to it. To address this problem, we will use a Java interface to implement a . In this design, whenever a KeyPad button is pressed, the KeyPad object calls a method in the Converter that displays the key’s label in the text area.

Figure [fig-p493f1] provides a summary of the callback design. Note that the association between the Converter and the KeyPad is bi-directional. This means that each object has a reference to the other and can invoke the other’s public methods. This will be effected by having the Converter pass a reference to itself when it constructs the KeyPad :

Another important design issue is that the KeyPad needs to know the name of the callback method and the Converter needs to have an implementation of that method. This is a perfect job for an abstract interface:

The KeyPad can interact with any class that implements the KeyPadClient interface. Note that the KeyPad has a reference to the , which it will use to invoke the keypressCallback() method.

The implementation of KeyPad is shown in Figure 13.17. Note that its constructor takes a reference to a KeyPadClient and saves it in an instance variable. Its actionPerformed() method then passes the key’s label to the KeyPadClient ’s callback method.

Given the KeyPad design, we need to revise our design of the Converter class (Fig. [fig-p493f1] ). The Converter will now implement the KeyPadClient interface, which means it must provide an implementation of the keypressCallback() method:

Recall that whenever the KeyPad object calls the keypressCallback() method, it passes the label of the button that was pressed. The Converter object simply appends the key’s label to the input text field, just as if the user typed the key in the text field.

The complete implementation of this revised version of the interface is shown in Figure 13.18 on the next page. The appearance of the interface itself is shown in Figure 3.19.

Figure 3.19 shows that despite our efforts to group the keypad into a rectangular array, it doesn’t appear as a single entity in the interface itself, which indicates a layout problem. The default layout for our KeyPad (which is a JPanel ) is FlowLayout , which is not appropriate for a numeric keypad that needs to be arranged into a two-dimensional grid pattern, which is the kind of layout our design called for (Fig. [fig-metricgui2] ).

Fortunately, this flaw can easily be fixed by using an appropriate layout manager from the AWT. In the next version of the program, we employ the java.awt.GridLayout , which is perfectly suited for a two-dimensional keypad layout (Section 13.7.2).

The lesson to be learned from this example is that screen layout is an important element of an effective GUI. If not done well, it can undermine the GUI’s effort to guide the user toward the appointed tasks. If done poorly enough, it can even keep the user from doing the task at all.

Java Case Study

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You have now covered many aspects of the Java language. In this chapter we are going to take stock of what you have learnt by developing a Java application that draws upon all these topics. We will implement interfaces; we will catch and throw exceptions; we will make use of the collection classes in the java . util package; and we will store objects to file. We will also make use of many JavaFX components to develop an attractive graphical interface.

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If you are developing a class from scratch that you wish to add into a package, your Java IDE can be used so that the package line is inserted into your code for you and the required directory structure is created. If you are using your Java IDE to revisit classes previously written outside of a package (as in this example), you may need to ensure that the resulting directory structure is reflected in the project you are working in. Refer to your IDE’s documentation for details about how to do this.

By default, the tabs you add will appear at the top left of the TabPane (as in Fig.  24.8 ). A setSide method can be used to choose an alternative side (the top right, the bottom, the left or the right).

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Web development today cannot altogether be separated from the enterprise application context. The components often work together. With the demand of high performance, transactional security, fluid navigation, and eye candy look and feel, designing a web application is really a daunting task. Once a great design is made, the application must be optimized to deal with the reality factors such as poor network bandwidth, surging traffic, browser limitations, and so forth. Each of them play a vital role in the designing process and can completely change design decisions. Changes are better handled at Winitial design phases than being sorry later. The article takes on some aspects of creating a Web application in the JEE framework with an example application.

Design Consideration

There are many best practices to design decisions that we often dearly adhere without considering the alternatives and tradeoff of using one over the other. For example, a B2C application may require focus on handling large traffic with pretty straightforward underlying domain logic. An automated processing system, on the other hand, may require high usability with complex UI and business processing. We cannot be naive and plug in the same pattern into almost every design need.

There are numerous standard design patterns available for Web presentation, such as Page Controller, Front Controller, MVC, MVP, MOVE , Template View, Transform View, Two Step View, Application Controller, and so on. To rate, perhaps Page Controller is the simplest whereas MVC is complex. MVC is the most relied-upon pattern in the enterprise arena. It may not be excellent but lays fine foundation in most cases. Interested readers may visit Martin Fowler’s Catalog of Patterns of Enterprise Application Architecture for detailed information on different types of patterns and their uses in software design.

Page Controller

This pattern has a one-module-per-page interface that acts as a controller for each logical page of the Web site. It states basic Web experience and can be structured with CGI script or Servlet. Perhaps, the first Servlet/JSP application you have written is the simplest example of this pattern.

This pattern is pretty simple, as is obvious. inappropriate for design consideration where complex layers of domain logic needs to be implemented.

Front Controller

This pattern is structured to handle Web site calls in two layers: Web handler and command hierarchy. Web handler pulls information from the post and gets request from the Web server and delegates responsibility to the appropriate command in the hierarchy to carry out the action. Because this pattern emphasizes on the responsibility of Web server mostly, it is easy to port the application from one server to another.

MVC (Model View Controller)

MVC is a widely used pattern, excellent at decoupling presentation concerns from the model. The model contains application-specific content and processing logic, including content objects, access to external data, and all application-specific processing functionality. the view contains UI-specific functionality that enables presentation of content and processing logic required by the end user. the controller maintains the liaison between the model and the view and coordinates flow of data between them. The controller is too much intertwined with the view and there is a very fine-line difference to call it a separate layer.

Because this pattern emphasis on the fact of the model layer, any application that has no real behavior in it in any manner is inappropriate. In the form of layer upon layer, it is quite suitable to implement a complicated design.

A Quick Example

To appreciate further, let’s implement this pattern with the help of a program. The idea is to create a CRUD Web application using techniques of JSF, EJB, and JPA. The database to work upon the following example is:

SQL: creating app_user table (in MySQL)

The following JPA Entity bean represents the model layer.

The EJB that represents the data access object class is as follows:

The implementation class for the EJB is:

Managed Bean

The managed bean class for the JSF that acts as the controller in the MVC layer is as follows:

userList.xhtml

The view layer is represented in JSF.

The Style Sheet for the JSF is as follows.

Creating a Web application in the JEE framework is not that difficult, but the challenge lies in optimizing performance in view of changing needs. JSF, EJB, and JPA make an excellent combo in easing the complexities of implementing Web application considerably. The precedingprogram is an interesting way to present CRUD functionalities in an application.

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• Java Arrays
• Java Strings
• Java Collection
• Java 8 Tutorial
• Java Multithreading
• Java Exception Handling
• Java Programs
• Java Project
• Java Collections Interview
• Java Interview Questions
• Spring Boot
• Java Programs - Java Programming Examples

Java Basic Programs

• How to Read and Print an Integer value in Java
• Ways to read input from console in Java
• Java Program to Multiply two Floating-Point Numbers
• Java Program to Swap Two Numbers
• Java Program to Add Two Binary Strings
• Java Program to Add two Complex Numbers
• Java Program to Check if a Given Integer is Odd or Even
• Java Program to Find the Largest of three Numbers
• Java Program to Find LCM of Two Numbers
• Java Program to Find GCD or HCF of Two Numbers
• Java Program to Display All Prime Numbers from 1 to N
• Java Program to Find if a Given Year is a Leap Year
• Java Program to Check Armstrong Number between Two Integers
• Java Program to Check If a Number is Neon Number or Not
• Java Program to Check Whether the Character is Vowel or Consonant
• Java Program for factorial of a number
• Java Program to Find Sum of Fibonacci Series Numbers of First N Even Indexes
• Java Program to Calculate Simple Interest
• Java Program for compound interest
• Java Program to Find the Perimeter of a Rectangle

Java Pattern Programs

• Java Program to Print Right Triangle Star Pattern
• Java Program to Print Left Triangle Star Pattern
• Java Program to Print Pyramid Number Pattern
• Java Program to Print Reverse Pyramid Star Pattern
• Java Program to Print Upper Star Triangle Pattern
• Java Program to Print Mirror Upper Star Triangle Pattern
• Java Program to Print Downward Triangle Star Pattern
• Java Program to Print Mirror Lower Star Triangle Pattern
• Java Program to Print Star Pascal’s Triangle
• Java Program to Print Diamond Shape Star Pattern
• Java Program to Print Square Star Pattern
• Java Program to Print Pyramid Star Pattern
• Java Program to Print Spiral Pattern of Numbers

Java Conversion Programs

• Java Program to Convert Binary to Octal
• Java Program to Convert Octal to Decimal
• Java Program For Decimal to Octal Conversion
• Java Program For Hexadecimal to Decimal Conversion
• Java Program For Decimal to Hexadecimal Conversion
• Java Program for Decimal to Binary Conversion
• Boolean toString() method in Java with examples
• Convert String to Double in Java
• Java Program to Convert Double to String
• Java Program to Convert String to Long
• Java Program to Convert Long to String
• Java Program For Int to Char Conversion
• Java Program to Convert Char to Int

Java Classes and Object Programs

• Classes and Objects in Java
• Abstract Class in Java
• Singleton Method Design Pattern in Java
• Interfaces in Java
• Encapsulation in Java
• Inheritance in Java
• Abstraction in Java
• Difference Between Data Hiding and Abstraction in Java
• Polymorphism in Java
• Method Overloading in Java
• Overriding in Java
• Super Keyword in Java
• 'this' reference in Java
• static Keyword in Java
• Access Modifiers in Java

Java Methods Programs

• Java main() Method - public static void main(String[] args)
• Difference between static and non-static method in Java
• HashTable forEach() method in Java with Examples
• StringBuilder toString() method in Java with Examples
• StringBuffer codePointAt() method in Java with Examples
• How compare() method works in Java
• Short equals() method in Java with Examples
• Difference Between next() and hasNext() Method in Java Collections
• What does start() function do in multithreading in Java?
• Difference between Thread.start() and Thread.run() in Java

Java Searching Programs

• Java Program for Linear Search
• Binary Search in Java
• Java Program To Recursively Linearly Search An Element In An Array

Java 1-D Array Programs

• Check if a value is present in an Array in Java
• Java Program to find largest element in an array
• Arrays.sort() in Java with examples
• Java Program to Sort the Array Elements in Descending Order
• Java Program to Sort the Elements of an Array in Ascending Order
• Remove duplicates from Sorted Array
• Java Program to Merge Two Arrays
• Java Program to Check if two Arrays are Equal or not
• Remove all occurrences of an element from Array in Java
• Java Program to Find Common Elements Between Two Arrays
• Array Copy in Java
• Java Program For Array Rotation

Java 2-D Arrays (Matrix) Programs

• Print a 2 D Array or Matrix in Java
• Java Program to Add two Matrices
• Sorting a 2D Array according to values in any given column in Java
• Java Program to Find Transpose of Matrix
• Java Program to Find the Determinant of a Matrix
• Java Program to Find the Normal and Trace of a Matrix
• Java Program to Print Boundary Elements of the Matrix
• Java Program to Rotate Matrix Elements
• Java Program to Compute the Sum of Diagonals of a Matrix
• Java Program to Interchange Elements of First and Last in a Matrix Across Rows
• Java Program to Interchange Elements of First and Last in a Matrix Across Columns

Java String Programs

• Java Program to get a character from a String
• Replace a character at a specific index in a String in Java
• Reverse a string in Java
• Java Program to Reverse a String using Stack
• Sort a String in Java (2 different ways)
• Swapping Pairs of Characters in a String in Java
• Check if a given string is Pangram in Java
• Print first letter of each word in a string using regex
• Java Program to Determine the Unicode Code Point at Given Index in String
• Remove Leading Zeros From String in Java
• Compare two Strings in Java
• Compare two strings lexicographically in Java
• Java program to print Even length words in a String
• Insert a String into another String in Java
• Split a String into a Number of Substrings in Java

Java List Programs

• Initializing a List in Java
• How to Find a Sublist in a List in Java?
• Min and Max in a List in Java
• Split a List into Two Halves in Java
• How to remove a SubList from a List in Java
• How to Remove Duplicates from ArrayList in Java
• How to sort an ArrayList in Ascending Order in Java
• Get first and last elements from ArrayList in Java
• Convert a List of String to a comma separated String in Java
• How to Add Element at First and Last Position of LinkedList in Java?
• Find common elements in two ArrayLists in Java
• Remove repeated elements from ArrayList in Java

Java Date and Time Programs

• Java Program to Format Time in AM-PM format
• Java Program to Display Dates of a Calendar Year in Different Format
• Java Program to Display Current Date and Time
• Java Program to Display Time in Different Country Format
• How to Convert Local Time to GMT in Java?

Java File Programs

• Java Program to Create a New File
• Java Program to Create a Temporary File
• Java Program to Rename a File
• Java Program to Make a File Read-Only
• Comparing Path of Two Files in Java
• Different Ways to Copy Content From One File to Another File in Java
• Java Program to Print all the Strings that Match a Given Pattern from a File
• Java Program to Append a String in an Existing File
• Java Program to Read Content From One File and Write it into Another File
• Java Program to Read and Print All Files From a Zip File

Java Directory Programs

• Java Program to Traverse in a Directory
• Java Program to Get the Size of a Directory
• Java Program to Delete a directory
• Java Program to Create Directories Recursively
• Java Program to Search for a File in a Directory
• Java Program to Find Current Working Directory
• Java Program to List all Files in a Directory and Nested Sub-Directories

Java Exceptions and Errors Programs

• Exceptions in Java
• Types of Errors in Java with Examples
• Java Program to Handle the Exception Hierarchies
• Java Program to Handle the Exception Methods
• Java Program to Handle Checked Exception
• Java Program to Handle Unchecked Exception
• Java Program to Handle Divide By Zero and Multiple Exceptions
• Unreachable Code Error in Java
• Thread Interference and Memory Consistency Errors in Java

Java Collections Programs

• Collections in Java
• How to Print a Collection in Java?
• Java Program to Compare Elements in a Collection
• Java Program to Get the Size of Collection and Verify that Collection is Empty
• Collections.shuffle() Method in Java with Examples
• Collections.reverse() Method in Java with Examples
• Java Program to Change a Collection to an Array
• Convert an Array into Collection in Java
• How to Replace a Element in Java ArrayList?
• Java Program to Rotate Elements of the List
• How to iterate any Map in Java

Java Multithreading Programs

• Thread isAlive() Method in Java With Examples
• How to Temporarily Stop a Thread in Java?
• Joining Threads in Java
• Daemon Thread in Java

Java More Java Programs

• Program to Print Fibonacci Series in Java
• How to convert LinkedList to Array in Java?
• Program to Convert a Vector to List in Java
• Convert a String to a List of Characters in Java
• Convert an Iterator to a List in Java
• Program to Convert List to Map in Java
• Program to Convert List to Stream in Java
• Convert List to Set in Java
• Java Program to Convert InputStream to String
• Convert Set of String to Array of String in Java
• Java Program to Convert String to Object
• How to Convert a String value to Byte value in Java with Examples

Java Programs – Java Programming Examples

Java is one of the most popular programming languages today because of its simplicity. Java programming concepts such as control statements, Arrays, Strings, Object-Oriented Programming (OOP) , etc. are very important from an interview perspective as well as from exams. 

So, whether you are a fresher preparing for job interviews or a beginner who has covered Java Fundamentals and wants to practice Java concepts then, this J ava Programming Examples page covers a wide range of Java programs in an organized manner.

In this article, we will learn and prepare for Interviews using Java Programming Examples . From basic Java programs like the Fibonacci series , Prime numbers , Factorial numbers , and Palindrome numbers to advanced Java programs.

So, keep scrolling or bookmark this page to learn about Java (Basic to Advanced) using Java Programming Examples.

Table of Content

This section, “Java Basic Programs,” provides a launchpad if you are new to Java programming. Here, you’ll encounter a collection of fundamental Java programs, that is crafted to introduce you to the core syntax, data structures, and control flow mechanisms of Java development.

• Java Program to Read The Number From Standard Input
• Java Program to Get Input from the User
• Java Program to Multiply Two Floating-Point Numbers
• Java Program to Add Two Complex Numbers
• Java Program to Check Even or Odd Integers
• Java Program to Find Largest Among 3 Numbers
• Java Program to Find LCM of 2 numbers
• Java Program to Find GCD or HCF of 2 numbers
• Java Program to Check Leap Year
• Java Program to Check whether the input number is a Neon Number
• Java Program to Check whether input character is vowel or consonant
• Java Program to Find Factorial of a number
• Java Program to Find Even Sum of Fibonacci Series Till number N
• Java Program to Calculate Compound Interest

In this section, you will get a list of Java programming language that deals with patterns. By meticulously arranging stars, numbers, or characters, you’ll not only solidify your grasp of Java loops and control structures but also discover the aesthetic side of programming.

• Java Program to Print Star Pascal’s Triangle
• Java Program to Print Diamond Star Pattern

Java Conversion Programs put your coding skills to the test. Here, you’ll encounter a series of exercises designed to strengthen your ability to transform data, like converting Binary to Decimal and more.

• Java Program For Binary to Octal Conversion
• Java Program For Octal to Decimal Conversion
• Java Program For Decimal to Binary Conversion
• Java Program For Binary to Decimal Conversion
• Java Program For Boolean to String Conversion
• Java Program For String to Double Conversion
• Java Program For Double to String Conversion
• Java Program For String to Long Conversion
• Java Program For Long to String Conversion
• Java Program For Char to Int Conversion

Here in this section, you will dive into the world of classes, acting as blueprints for objects, and objects themselves, the real-life entities.

• Java Program to Create a Class and Object
• Java Program to Create Abstract Class
• Java Program to Create Singleton Class
• Java Program to Create an Interface
• Java Program to Show Encapsulation in Class
• Java Program to Show Inheritance in Class
• Java Program to Show Abstraction in Class
• Java Program to Show Data Hiding in Class
• Java Program to Show Polymorphism in Class
• Java Program to Show Overloading of Methods in Class
• Java Program to Show Overriding of Methods in Classes
• Java Program to Show Use of Super Keyword in Class
• Java Program to Show Use of This Keyword in Class
• Java Program to Show Usage of Static keyword in Class
• Java Program to Show Usage of Access Modifier

This section unlocks the secrets of methods, the building blocks of reusability in object-oriented programming. Here, you’ll embark on a hands-on journey, crafting and wielding methods like a programming pro.

• Java Program to Show Usage of Main() method
• Java Program to Show Use of Static and Non-static Methods
• Java Program to Show Usage of forEach() Method
• Java Program to Show Usage of toString() Method
• Java Program to Show Usage of codePointAt() Method
• Java Program to Show Usage of compare() Method
• Java Program to Show Usage of equals() Method
• Java Program to Show Usage of hasNext() and next() Method
• start() Method
• run() Method

Looking for the Java Search related programs, hence here in this section we have listed down multiple searching Java programming examples.

• Java Program For Linear Search
• Java Program For Binary Search
• Java Program to Recursively Linearly Search an Element in an Array

This section is all about organizing things in your Java code. Here, you’ll learn how to create these “cabinets,” put things in them, and take them out whenever you need them.

• Java Program to Search an Element in an Array
• Java Program to Find the Largest Element in an Array
• Java Program to Sort an Array
• Java Program to Sort the Elements of an Array in Descending Order
• Java Program to Remove Duplicate Elements From an Array
• Java Program to Check if Two Arrays Are Equal or Not
• Java Program to Remove All Occurrences of an Element in an Array
• Java Program to Find Common Array Elements
• Java Program to Copy All the Elements of One Array to Another Array

This section dives into two-dimensional arrays, which are like spreadsheets for your code. Imagine organizing data in rows and columns, perfect for things like tables or images.

• Java Program to Print a 2D Array
• Java Program to Add Two Matrices
• Java Program to Sort the 2D Array Across Columns
• Java Program to Check Whether Two Matrices Are Equal or Not
• Java Program to Find the Transpose
• Java Program to Find the Determinant
• Java Program to Find the Normal and Trace
• Java Program to Print Boundary Elements of a Matrix

In this section, you will dive deep into working with text in Java. You’ll learn to manipulate, analyze, and modify strings, the fundamental building blocks of text data, with the help of multiple Java String programs.

• Java Program to Get a Character From the Given String
• Java Program to Replace a Character at a Specific Index
• Java Program to Reverse a String
• Java Program to Reverse a String Using Stacks
• Java Program to Sort a String
• Java Program to Swapping Pair of Characters
• Java Program to Check Whether the Given String is Pangram
• Java Program to Print first letter of each word using regex
• Java Program to Determine the Unicode Code Point at a given index
• Java Program to Remove leading zeros
• Java Program to Compare two strings
• Java Program to Compare two strings lexicographically
• Java Program to Print even length words
• Java Program to Insert a string into another string
• Java Program to Splitting into a number of sub-strings

Dive into the world of Java Lists, a fundamental data structure in Java. Here, you’ll learn how to store, access, and manipulate elements in a specific sequence.

• Java Program to Initializing a List
• Java Program to Find a Sublist in a List
• Java Program to Get Minimum and Maximum From a List
• Java Program to Split a list into Two Halves
• Java Program to Remove a Sublist from a List
• Java Program to Remove Duplicates from an Array List
• Java Program to Remove Null from a List container
• Java Program to Sort Array List in an Ascending Order
• Java Program to Get First and Last Elements from an Array List
• Java Program to Convert a List of String to Comma Separated String
• Java Program to Add Element at First and Last Position of a Linked list
• Java Program to Find Common Elements in Two ArrayList
• Java Program to Remove Repeated Element From An ArrayList

This section gives you to handle the ever-changing world of dates and times within your Java programs. Explore the working with calendars, timestamps, and time manipulation – essential skills for building applications that deal with deadlines, scheduling, or even historical data analysis.

• Java Program to Format time in AM-PM format
• Java Program to Display Dates of Calendar Year in Different Format
• Java Program to Display current date and time
• Java Program to Display time in different country’s format
• Java Program to Convert the local Time to GMT

Java File Programs empowers you to interact with files in Java. This section dives deep into reading, writing, and manipulating data stored outside your program.

• Java Program to Create a new file
• Java Program to Create a temporary file
• Java Program to Write into a file
• Java Program to Rename a file in java
• Java Program to Compare Paths of Two files
• Java Program to Copy one file into another file
• Java Program to Print all the Pattern that Matches Given Pattern From a File
• Java Program to Read content from one file and writing it into another file
• Java Program to Read and printing all files from a zip file

This section navigate you to the world of directories and files in Java. Through this Java programming examples “Java Directory” section you’ll master creating, manipulating, and interacting with directories.

• Java Program to Traverse in a directory
• Java Program to Get the size of a directory
• Java Program to Delete a Directory
• Java Program to Create directories recursively
• Java Program to Search for a file in a directory
• Java Program to Find the current working directory
• Java Program to Display all the directories in a directory

Through a series of hands-on exercises on Java Exceptions and Errors Handling programs, you will easily get to know how to become a good Java programmer.

• Java Program to Show Runtime Exceptions
• Java Program to Show Types of Errors
• Java program to Handle the Checked exceptions
• Java Program to Handle the Unchecked Exceptions
• Java Program to Show Unreachable Code Error
• Java Program to Show Thread interface and memory consistency errors

Java Collections is not just about storing your data in Java; So practicing Java Collections programs will help you boost your organization skills. Get deep down into lists, sets, maps, and more, and discover how to structure your data effectively to build robust and efficient Java applications.

• Java Program to Use Different Types of Collection
• Java Program to Print a Collection
• Java Program to Get the Size of the Collection
• Java Program to Shuffle the Elements of a Collection
• Java Program to Reverse a Collection
• Java Program to Convert Collection into Array
• Java Program to Convert Array into Collection
• Java Program to Replace Elements in a List
• Java Program to Rotate Elements of a List
• Java Program to Iterate through Elements of HashMap

In this section you will get hand on Java Multithreading programs. It will help you to conquer the art of threading, a technique that lets your program handle multiple tasks seemingly at once.

• Java Program to Check the Thread Status
• Java Program to Suspend a thread
• Java Program to Join Threads
• Java Program to Show Daemon Thread

This section extends your coding experience with a diverse array of programs that explore more intricate functionalities. Brace yourself to tackle problems that involve algorithms, data manipulation, and object-oriented programming concepts.

• Java Program to Print Fibonacci Series in Different Ways
• Java Program to Convert Linked List to an Array
• Java Program to Convert Vector to a List
• Java Program to Convert String to a List of Characters
• Java Program to Convert Iterator to a List
• Java Program to Convert List to a Map
• Java Program to Convert List to a Stream
• Java Program to Convert List to Set
• Java Program to Convert Set of String to Array of String
• Java Program to Convert string value to byte value

In this article, we dealt with a variety of Java programming questions categorized as basic programs, control statements, Arrays , Strings , OOPs , and much more that are frequently asked in interviews and exams.

Each Java program will give you a different approach to solving a particular problem in Java. If you are new to Java programming, we highly recommend you to go through our article on Java tutorial , where we’ve covered all the basics and advanced topics of Java programming with practical examples and programs.

Click Here to Check out Java Exercise to Practice Java Problems Online.

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Chapter 51 Duke’s Bookstore Case Study Example

The Duke’s Bookstore example is a simple e-commerce application that illustrates some of the more advanced features of JavaServer Faces technology in combination with Contexts and Dependency Injection for the Java EE Platform (CDI), enterprise beans, and the Java Persistence API. Users can select books from an image map, view the bookstore catalog, and purchase books. No security is used in this application.

The following topics are addressed here:

Design and Architecture of Duke's Bookstore

The Duke's Bookstore Interface

Running the Duke's Bookstore Case Study Application

Copyright © 2013, Oracle and/or its affiliates. All rights reserved. Legal Notices

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Tackling the Arrow Anti-Pattern in Java: A Case Study

When developing software, maintaining clean and readable code is crucial. One common pitfall that hampers readability and maintainability is the “Arrow Anti-Pattern” . This pattern emerges when code is heavily nested, leading to a structure that visually resembles an arrow pointing to the right. Let’s explore this anti-pattern using a Java example and discuss strategies to refactor and improve the code.

Understanding the Arrow Anti-Pattern

The Arrow Anti-Pattern occurs primarily due to deeply nested conditional structures. This usually happens when developers continue to add levels of if statements or loops within others, often in an attempt to handle multiple conditions. While the intentions are to address various scenarios rigorously, the result is often a convoluted mess that’s hard to read, debug, and maintain.

Example: A Java Login Processor

Consider the following Java class, which processes user logins:

This code is a classic example of the Arrow Anti-Pattern. Each conditional statement increases the level of indentation, causing the code to shift further right, making it cumbersome and visually unappealing.

Refactoring the Arrow Anti-Pattern

Refactoring aims to simplify and clarify code without changing its functionality. For the Arrow Anti-Pattern, the goal is to reduce nesting and improve readability. One effective technique is using early returns to handle error conditions or special cases upfront.

Refactored Version

Here’s how you can refactor the aforementioned Java code using early returns:

Benefits of Refactoring

• Readability : By eliminating excessive nesting, the code becomes easier to read. Each condition is checked sequentially, and actions are taken immediately when conditions are not met.
• Maintainability : Simpler code means easier maintenance. Changes can be made more confidently without the fear of disrupting deeply nested logic.
• Debugging : Debugging becomes more straightforward because the flow of execution is clearer and more linear.

Avoiding or refactoring out of the Arrow Anti-Pattern is essential for keeping your codebase clean and maintainable. By applying techniques like early returns, you can significantly improve the structure of your code. Always remember that readable code means maintainable code, which is key to long-term project success.

By addressing the Arrow Anti-Pattern in commonly encountered scenarios, such as a login processor, developers can ensure their applications remain robust, scalable, and easy to manage.

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Learn Java Java Tutoring is a resource blog on java focused mostly on beginners to learn Java in the simplest way without much effort you can access unlimited programs, interview questions, examples

Java programs – 500+ simple & basic programs with outputs.

in Java Programs , Java Tutorials March 6, 2024 Comments Off on Java Programs – 500+ Simple & Basic Programs With Outputs

Java programs: Basic Java programs with examples & outputs. Here we covered over the list of 500+ Java simple programs for beginners to advance, practice & understood how java programming works. You can take a pdf of each program along with source codes & outputs.

In case if you are looking out for C Programs , you can check out that link.

We covered major Simple to basic Java Programs along with sample solutions for each method. If you need any custom program you can contact us.

All of our Sample Java programs with outputs in pdf format are written by expert authors who had high command on Java programming. Even our Java Tutorials are with rich in-depth content so that newcomers can easily understand.

1. EXECUTION OF A JAVA PROGRAM   

Static loading :  A block of code would be loaded into the RAM before it executed ( i.e after being loaded into the RAM it may or may not get executed )

Dynamic loading:   A block of code would be loaded into the RAM only when it is required to be executed.

Note:   Static loading took place in the execution of structured programming languages. EX:  c- language

Java  follows the Dynamic loading

–     JVM would not convert all the statements of the class file into its executable code at a time.

–     Once the control comes out from the method, then it is deleted from the RAM and another method of exe type will be loaded as required.

–     Once the control comes out from the main ( ), the main ( ) method would also be deleted from the RAM. This is why we are not able to view the exe contents of a class file.

Simple Hello Word Program

Out of 500+ Simple & Basic Java Programs: Hello world is a first-ever program which we published on our site. Of course, Every Java programmer or C programmer will start with a “Hello World Program”. Followed by the rest of the programs in different Categories.

Basic Java Programs – Complete List Here

Advanced simple programming examples with sample outputs, string, array programs.

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Conversion Programs:

Star & Number Pattern Programs

Functions of JVM:

• It converts the required part if the bytecode into its equivalent executable code.
• It loads the executable code into the RAM.
• Executes this code through the local operating system.
• Deletes the executable code from the RAM.

We know that JVM converts the class file into its equivalent executable code. Now if a JVM is in windows environment executable code that is understood by windows environment only.

Similarly, same in the case with UNIX or other or thus JVM ID platform dependent.

Java, With the help of this course, students can now get a confidant to write a basic program to in-depth algorithms in C Programming or Java Programming to understand the basics one must visit the list 500 Java programs to get an idea.

Users can now download the top 100 Basic Java programming examples in a pdf format to practice.

But the platform dependency of the JVM is not considered while saying Java is platform independent because JVM is supplied free of cost through the internet by the sun microsystems.

Platform independence :

Compiled code of a program should be executed in any operating system, irrespective of the as in OS in which that code had been generated. This concept is known as platform independence.

• The birth of oops concept took place with encapsulation.
• Any program contains two parts.
• Date part and Logic part
• Out of data and logic the highest priority we have given to data.
• But in a structured programming language, the data insecurity is high.
• Thus in a process, if securing data in structured prog. lang. the concept of encapsulation came into existence.

Note: In structured programming lang programs, the global variable play a vital role.

But because of these global variables, there is data insecurity in the structured programming lang programs. i.e functions that are not related to some variables will have access to those variables and thus data may get corrupted. In this way data is unsecured.

“This is what people say in general about data insecurity. But this is not the actual reason. The actual concept is as follows”.

Let us assume that, we have a ‘C’ program with a hundred functions. Assume that it is a project. Now if any upgradation is required, then the client i.e the user of this program (s/w) comes to its company and asks the programmers to update it according to his requirement.

Now we should note that it is not guaranteed that the programmers who developed this program will still be working with that company. Hence this project falls into the hands of new programmers.

Automatically it takes a lot of time to study. The project itself before upgrading it. It may not be surprising that the time required for writing the code to upgrade the project may be very less when compared to the time required for studying the project.

Thus maintenance becomes a problem.

If the new programmer adds a new function to the existing code in the way of upgrading it, there is no guarantee that it will not affect the existing functions in the code. This is because of global variables. In this way, data insecurity is created.

• To overcome this problem, programmers developed the concept of encapsulation .
• For example, let us have a struc.prog.lang. program with ten global variables and twenty functions.
• It is sure that all the twenty functions will not use all the global variables .

Three of the global variables may be used only by two functions. But in a structured prog. Lang like ‘C’ it is not possible to restrict the access of global variables by some limited no of functions.

Every function will have access to all the global variables.

To avoid this problem, programmers have designed a way such that the variables and the functions which are associated with or operate on those variables are enclosed in a block and that bock is called a class and that class and that class is given a name, Just as a function is given a name.

Now the variables inside the block cannot be called as the local variable because they cannot be called as global variables because they are confined to a block and not global.

Hence these variables are known as instance variables

_______________________________________________________________

Example 2 :

Therefore a class is nothing but grouping data along with its functionalities.

Note 1:  E ncapsulation it’s the concept of binding data along with its corresponding functionalities.

Encapsulations came into existence in order to provide security for the data present inside the program.

Note 2: Any object oriental programming language file looks like a group of classes. Everything is encapsulated. Nothing is outside the class.

• Encapsulation is the backbone of oop languages.
• JAVA supports all the oop concepts ( i.e. encapsulation, polymorphism, inheritance) and hence it is known as an object-oriented programming language.
• C++ breaks the concept of encapsulation because the main ( ) method in a  C++ program is declared outside a class. Hence it is not a pure oop language, in fact, it is a poor oop language.

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The switch statement allows us to execute a block of code among many alternatives.

How does the switch-case statement work?

The expression is evaluated once and compared with the values of each case.

• If expression matches with value1 , the code of case value1 are executed. Similarly, the code of case value2 is executed if expression matches with value2
• If there is no match, the code of the default case is executed

Note : The working of the switch-case statement is similar to the Java if...else...if ladder . However, the syntax of the switch statement is cleaner and much easier to read and write.

Example: Java switch Statement

In the above example, we have used the switch statement to find the size. Here, we have a variable number . The variable is compared with the value of each case statement.

Since the value matches with 44 , the code of case 44 is executed.

Here, the size variable is assigned with the value Large .

• Create a Simple Calculator Using the Java switch Statement

Flowchart of switch Statement

break Statement in Java switch...case

Notice that we have been using break in each case block.

The break statement is used to terminate the switch-case statement. If break is not used, all the cases after the matching case are also executed. For example,

In the above example, expression matches with case 2 . Here, we haven't used the break statement after each case.

Hence, all the cases after case 2 are also executed.

This is why the break statement is needed to terminate the switch-case statement after the matching case. To learn more, visit Java break Statement .

default Case in Java switch-case

The switch statement also includes an optional default case . It is executed when the expression doesn't match any of the cases. For example,

In the above example, we have created a switch-case statement. Here, the value of expression doesn't match with any of the cases.

Hence, the code inside the default case is executed.

Note : The Java switch statement only works with:

• Primitive data types : byte, short, char, and int
• Enumerated types
• String Class
• Wrapper Classes : Character, Byte, Short, and Integer.
• Implementation of switch...case on Strings

Table of Contents

• Java Switch Statement
• Example: switch statement
• Flowchart of switch...case
• break statement
• default case

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