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Compiling and running Java code

Compiling and running Java code

1.3 Your First Java Programtestinganswers.com

Java, a widely used programming language, follows a two-step process for executing programs: compilation and execution. In this guide, we’ll walk through the steps of compiling and running Java code, providing detailed explanations, code examples, and images.

1. Introduction

Java is a compiled language, which means that before it can be executed, the source code must be translated into an intermediate form called bytecode. This bytecode is then interpreted and executed by the Java Virtual Machine (JVM).

2. Setting up Java

Before you can compile and run Java code, ensure that Java Development Kit (JDK) is installed on your system. You can download the latest JDK from the official Oracle website.

Verify your installation by opening a terminal or command prompt and running:

bash:
javac -version
java -version

You should see version information for the Java compiler (javac) and the Java Virtual Machine (java).

3. Writing a Simple Java Program

Create a file named HelloWorld.java with the following content:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

This program prints “Hello, World!” to the console.

4. Compiling Java Code

Open a terminal or command prompt, navigate to the directory containing HelloWorld.java, and execute the following command:

bash:
javac HelloWorld.java

This command invokes the Java compiler (javac) to compile the source code. If there are no errors, it will generate a file named HelloWorld.class, which contains the bytecode.

5. Running Java Code

After successful compilation, run the program using the following command:

bash:
java HelloWorld

This command executes the Java Virtual Machine (java), specifying the class name (HelloWorld). You should see the output:

Hello, World!

Congratulations! You’ve successfully compiled and run your first Java program.

6. Common Issues and Troubleshooting

a. Class Not Found Error

If you encounter a “class not found” error, ensure that you are in the correct directory and that the compiled .class file is present.

b. Syntax Errors

Carefully review error messages provided by the compiler. Syntax errors must be fixed before successful compilation.

c. Incorrect JDK Version

Ensure that your JDK version is compatible with the language features used in your code.

Compiling and running Java code involves a straightforward process. By following the steps outlined in this guide, you can successfully create, compile, and execute Java programs.