java 编译执行cmd命令

public class Hello{
    public static void main(String[] args) {
        System.out.println("Hello World!");
        for (int i = 0; i < 10; i++) {
            for (int k = 0; k < i; k++ ) {
                System.out.print(" ");
            }
            for (int j = 10; j > i; j-- ) {
                System.out.print(" *");
            }
            System.out.println("");
        }
    }
}

编译

　　javac Hello.java

执行

　　java Hello