Program development steps illustrate:
After development environment set up is completed, we can develop the first Java environment.
Java developers three-step: write | compile | run.
Java application development three steps:
Write your first Java program (HelloWorld):
1. In the C: \ directory under the new text file, the full file name changed to HelloWorld.java, in which a file named HelloWorld, the suffix must .java
2. Write a program:
public class HelloWorld{ public static void main(String[] args) { System.out.println("Hello,World"); } }
3. Compile and run the program:
4. code comments:
//第一行的第三个单词必须和所在的文件名称完全一样,大小写也要一样,大小写也要一样 //public class后面代表定义一个类的名称,类是Java当中所有源代码的基本组织单位: public class HelloWorld{ //第二行是万年不变的固定写法,代表main方法 //这一行代表程序执行的起点 public static void main(String[] args) { /* 第三行代表打印输出语句(其实就是屏幕显示) 希望显示什么东西,就在小括号当中填写什么内容 */ System.out.println("Hello,World"); } }