import java.awt.*;

import javax.swing.JFrame;


public class La extends JFrame {
    public La(){
        setSize(300, 300);
        setLayout(new GridLayout(3,3));
        setVisible(true);
    }
    public static void main(String[]args){
        String str[]={"1","2","3","4","5","6","7","8","9"};
        Button bt[]=new Button[str.length];
        La la=new La();
        for(int i=0;i<str.length;i++){
            bt[i]=new Button(str[i]);
            la.add(bt[i]);
        }
    }
}

自己参考一下，我没时间给你注释，不懂再问

看看吧http://www.高淇Java300集视频教程
也是刚学

if(myname=="菜刀"&&yourname=="西瓜"){
                 System.out.println("菜刀和西瓜");

             }
改为
if(myname.equals"菜刀"&&yourname.equals西瓜"){
                 System.out.println("菜刀和西瓜");

             }