新建一个Welcom.java文件，注意后缀名是java，不要搞成了java.txt，然后把下面的代码复制进去。

/**
 * This program displays a greeting for the reader.
 * @version 1.30 2014-02-27
 * @author Cay Horstmann
 */
public class Welcome
{
   public static void main(String[] args)
   {
      String greeting = "Welcome to Core Java!";
      System.out.println(greeting);
      for (int i = 0; i < greeting.length(); i++)
         System.out.print("=");
      System.out.println();
   }
}

cmd命令进到这个文件目录，运行
javac Welcome.java
java Welcome
cmd命令行屏幕显示如下：

E:\corejava\v1ch02\Welcome>javac Welcome.java

E:\corejava\v1ch02\Welcome>java Welcome
Welcome to Core Java!
=====================

E:\corejava\v1ch02\Welcome>