哥java学识有大进 干回之前的小学生系统像切菜一样简单 不说了 来代码

 package runok;
 import java.util.*;
 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;

 import javax.swing.*;
 public class vv extends JFrame implements ActionListener{

 /**
 * 作者：范铭祥
 * 功能：一个简单的小学生四则运算 自动 生成系统
 */
 JPanel jp1,jp2,jp3;
 JLabel jlb1,jlb2;
 JButton jb1;
 JTextField jtf1,jtf2;
 JTextArea ee;
 public double w1;
 public double m1;
 String fh;
 public static void main(String[] args)
 {
   vv start=new vv();
 }
 public vv()
 {
     jp1=new JPanel();
     jp2=new JPanel();
     jp3=new JPanel();

     jlb1=new JLabel("题目");
     jlb2=new JLabel("你的答案:");

     jb1=new JButton("判断答案");
     jb1.addActionListener(this);
     jb1.setActionCommand("aa");
     JTextArea txtArea = new JTextArea(1,15);
     jtf2=new JTextField(20);
    ee = new JTextArea(1,10);
     //设置布局管理
     this.setLayout(new GridLayout(3,1));
     //加入各个组件
     jp1.add(jlb1);
     jp1.add(txtArea);

     jp2.add(jlb2);
     jp2.add(jtf2);
     jp3.add(jb1);
     jp3.add(ee);
     //加入到JFrame
     this.add(jp1);
     this.add(jp2);
     this.add(jp3);
 //在这里用yy方法来获取题目 w 符号 m
     yy tt=new yy();

     w1=tt.ret1();
     m1=tt.ret2();
     fh=tt.ret3();
     txtArea.append(w1+fh+m1);
     this.setSize(400, 250);
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     this.setVisible(true);
 }
 public void yes()
 { ee.append("正确！");    }
 public void no()
 {ee.append("错误！");}
 public void cc()
 {
     int answer=(int) (Double.parseDouble(jtf2.getText()));;
         if(fh.equals("+"))
         {
             if(answer==w1+m1){
                 yes();
             }else{
                 no();
             }
         }
         if(fh.equals("-"))
         {
                 if(answer==w1-m1){
                     yes();
                 }else{
                     no();
                 }
         }
         if(fh.equals("*"))
         {
                 if(answer==w1*m1){
                    yes();
                 }else{
                    no();
                 }
         }
         if(fh.equals("/"))
         {
                 if(answer==w1/m1){
                     yes();
                 }else{
                     no();
                 }
         }
 }
 @Override
 public void actionPerformed(ActionEvent e)
     {
     // !!!!
     if(e.getActionCommand()=="aa")
     {
         cc();
     }
     }

 }

 class yy
 {
     private int max=4;
     private int min=1;
     private double w2,m2;
     private String ff;
     Random random = new Random();

     //System.out.println(s);
     public yy()
     {
     int s = random.nextInt(max)%(max-min+1) + min;

     double x=random.nextInt(max-2)%(max-2-min+1) + min;

     double y=random.nextInt(max-1)%(max-1-min+1) + min;
     int y1up=(int) Math.pow(10,x);
     int y1dn=(int) Math.pow(10,x-1);
     int y2up=(int) Math.pow(10,y);
     int y2dn=(int) Math.pow(10,y-1);
     int x_y1=random.nextInt(y1up)%(y1up-y1dn+1) + y1dn;
     int x_y2=random.nextInt(y2up)%(y2up-y2dn+1) + y2dn;
     double w=(double)x_y1;
     double m=(double)x_y2;
     this.w2=w;
     this.m2=m;
     switch(s)
     {
     case 1:
     {
     this.ff="+";
     System.out.println(w+"+"+m+"=" );
     break;
     }
     case 2:
     {
     this.ff="-";
     System.out.println(w+"-"+m+"=" );
     break;
     }
     case 3:
     {
     this.ff="*";
     System.out.println(w+"*"+m+"=" );
     break;
     }
     case 4:
     {
     this.ff="/";
     System.out.println(w+"/"+m+"=" );
     break;
     }

     }
     }
     public double ret1()
     {
         return w2;
     }
     public double ret2()
     {
         return m2;
     }
     public String ret3()
     {
         return ff;
     }
 }