用java编写helloworld的程序(记事本编写helloworld程序)

Introduction

In the world of programming, the first introduction to any language is usually done by writing a "Hello World" program. A "Hello World" program is a simple program that just outputs the phrase "Hello, World!" to the console or any other output device. In this article, we will learn how to write a "Hello World" program in Java, one of the most popular programming languages in the world.

Setting Up Java Environment

To write Java programs, we need to have the Java Development Kit (JDK) installed on our machine. We can download and install the latest version of the JDK from the official Java website. Once the JDK is installed, we can proceed to write our first Java program.

Writing the "Hello World" Program

To write the "Hello World" program in Java, we need to open a text editor and type in the following code:

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

This code creates a class called "HelloWorld" and defines a method called "main". The "main" method is the entry point of any Java program. It takes an array of Strings as input and outputs the phrase "Hello, World!" to the console using the "System.out.println" method. Once we have typed in the code, we need to save the file with the name "HelloWorld.java".

Compiling and Running the Program

Once we have saved the file, we need to compile it into bytecode using the Java compiler. We can open a command prompt or terminal window and navigate to the folder where the "HelloWorld.java" file is saved. Then, we can type in the following command to compile the code:

javac HelloWorld.java

If our code has no errors, the compiler will generate a file called "HelloWorld.class" in the same folder. This file contains the bytecode of our program.
To run the program, we need to use the "java" command followed by the name of the class that contains the "main" method. We can type in the following command:

java HelloWorld

This will output the phrase "Hello, World!" to the console or any other output device.

Conclusion

In this article, we have learned how to write a "Hello World" program in Java. We have also learned how to compile and run the program using the Java compiler and the "java" command. This is just the first step in learning Java programming. There are many more concepts to learn and explore in Java. But, this program serves as a good starting point for beginners who want to learn Java. So, go ahead and try out this program on your own and explore the wonderful world of Java programming.