急求解答！

Question

import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Font;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class MyCalculator extends Frame implements ActionListener {
 
 String buttonText [] = {"0","1","2","3","4","5","6","7","8","9",".","+","-","×","÷","=","C"};
 Panel toolBar = new Panel();
 double num1=0,num2=0;
 Button button [] = new Button[17];
 TextField screen;
 String calculate="";
public void lanchFrame(){
  
  setVisible(true);
  this.setBounds(200, 300, 200, 300);
  this.setResizable(false);
  this.addWindowListener(new WindowAdapter(){
   public void windowClosing(WindowEvent a) {
    System.exit(0);
   }
   
  });
  this.setTitle("MyCalculator");
  screen = new TextField(20);
  screen.addActionListener(this);
  add(screen,BorderLayout.NORTH);
  toolBar.setFont(new Font(null,Font.BOLD,30));
  toolBar.setLayout(new GridLayout(6,3,3,3));
  
  for(int i=0;i<17;i++){
   button [i] = new Button(buttonText[i]);
   button [i].addActionListener(this);
   toolBar.add(button [i]);
  }
  add(toolBar);
  
 }
 
 public static void main (String[]args){
  MyCalculator a = new MyCalculator();
  a.lanchFrame();
 }public void actionPerformed(ActionEvent e) {
   try{  
  Object definer = e.getSource();
  
  for(int i=0;i<17;i++){
   if(definer.equals(button[i])){
    if(i<10){
     screen.setText(screen.getText()+i);
    }
    if(i==10){
     screen.setText(screen.getText()+".");
    }
    if((i>10)&&(i<15)){
     num1=Double.parseDouble(screen.getText());
     calculate=e.getActionCommand();
     screen.setText("");
    }
    if(i==15){
     num2=Double.parseDouble(screen.getText());
     if(calculate.equals("+")){
         screen.setText(""+(num1+num2));
     }
     if(calculate.equals("-")){
      screen.setText(""+(num1-num2)); 
     }
     if(calculate.equals("×")){
      screen.setText(""+(num1*num2));
     }
     if(calculate.equals("÷")){
      screen.setText(""+(num1/num2));
     }
     
    }
    if(i==16){
     screen.setText("");
     calculate="";
     num1=0;
     num2=0;
    }
   }
  }
   }
   catch(Exception err){
    
   }
 
}
无法运行,帮我改改！

Answer 1

import java.awt.BorderLayout; 
import java.awt.Button; 
import java.awt.Font; 
import java.awt.Frame; 
import java.awt.GridLayout; 
import java.awt.Panel; 
import java.awt.TextField; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.WindowAdapter; 
import java.awt.event.WindowEvent; 
 class MyCalculator extends Frame implements ActionListener {      String buttonText[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
                           ".", "+", "-", "×", "÷", "=", "C"};
     Panel toolBar = new Panel();
     double num1 = 0, num2 = 0;
     Button button[] = new Button[17];
     TextField screen;
     String calculate = "";
     public void lanchFrame() {         setVisible(true);
         this.setBounds(200, 300, 200, 300);
         this.setResizable(false);
         this.addWindowListener(new WindowAdapter() {
             public void windowClosing(WindowEvent a) {
                 System.exit(0);
             }         });
         this.setTitle("MyCalculator");
         screen = new TextField(20);
         screen.addActionListener(this);
         add(screen, BorderLayout.NORTH);
         toolBar.setFont(new Font(null, Font.BOLD, 30));
         toolBar.setLayout(new GridLayout(6, 3, 3, 3));         for (int i = 0; i < 17; i++) {
             button[i] = new Button(buttonText[i]);
             button[i].addActionListener(this);
             toolBar.add(button[i]);
         }
         add(toolBar);     }     public static void main(String[] args) {
         MyCalculator a = new MyCalculator();
         a.lanchFrame();
     }     public void actionPerformed(ActionEvent e) {
         try {
             Object definer = e.getSource();             for (int i = 0; i < 17; i++) {
                 if (definer.equals(button[i])) {
                     if (i < 10) {
                         screen.setText(screen.getText() + i);
                     }
                     if (i == 10) {
                         screen.setText(screen.getText() + ".");
                     }
                     if ((i > 10) && (i < 15)) {
                         num1 = Double.parseDouble(screen.getText());
                         calculate = e.getActionCommand();
                         screen.setText("");
                     }
                     if (i == 15) {
                         num2 = Double.parseDouble(screen.getText());
                         if (calculate.equals("+")) {
                             screen.setText("" + (num1 + num2));
                         }
                         if (calculate.equals("-")) {
                             screen.setText("" + (num1 - num2));
                         }
                         if (calculate.equals("×")) {
                             screen.setText("" + (num1 * num2));
                         }
                         if (calculate.equals("÷")) {
                             screen.setText("" + (num1 / num2));
                         }                     }
                     if (i == 16) {
                         screen.setText("");
                         calculate = "";
                         num1 = 0;
                         num2 = 0;
                     }
                 }
             }
         } catch (Exception err) {         }     }
 }
可以运行；了