Creating First Java Application

Table of Contents

Overview

In this tutorial, we will learn the steps involved to create First Java Application. The following instructions are for users of the Windows operating system.

To code the first Java program, we’ll need:

JDK(Java Development Kit)
Set JAVA_HOME environment variable
Appended the JDK bin directory to the PATH variable
Text editor like Notepad, Notepad++, etc.

Steps to download and install JDK on Windows:

https://www.testingdocs.com/download-and-installing-java-jdk/

Instructions to download and install Notepad++ text editor on Windows:

https://www.testingdocs.com/installing-notepad-editor-on-windows-10/

Java Program

Our first Java program, HelloWorldJavaApp, will display the “Hello world!” greeting message on to the console output. To create this Java program, we will:

Create a Java Source File
Compile the Java source file to .class file
Run the Java Application

Create a Java Source File

The source file contains the Java code, written in the Java programming language. The source code is in human readable format, so that we can understand the code. We can use the text editor to create the source files.

Open Text Editor.

Add the following Java source code.

/**
 * The HelloWorldJavaApp application
 * Prints the message "Hello World!" to standard output.
 * Java Tutorials - www.TestingDocs.com
 */
public class HelloWorldJavaApp {

 public static void main(String[] args) {
 System.out.println("Hello World!"); 
// Display the greeting.
 }
}

Save the file as HelloWorldJavaApp.java

Java Source Code Notepad++ Editor

Compile the Java source file to .class file

The Java programming language compiler (javac) takes the source file and translates it into instructions that the JVM (Java Virtual Machine) can understand. The instructions contained within this file is the Java bytecode.

To compile the Java source file, change the current directory to the directory where the Java source file is located. At the prompt, type the following command and press Enter.

\> javac HelloWorldJavaApp.java

The compiler will generate a bytecode class file, HelloWorldJavaApp.class

We can find the javac and java in the JDK bin directory.(%JAVA_HOME%\bin)

We can set the JAVA_HOME environment variable and appended the JDK bin directory to the PATH variable.

Java JDK Tools bin Directory