实现键盘监听的计数器问题（附代码），键盘不起作用 - JAVA论坛

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谢谢大家的帮忙，错误我自己改过来的，下面是计数器所有代码

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class Calculatorapn
{

public static void main(String[] args)
{
JFrame cul=new cal();
cul.show();
}
}
class cal extends JFrame implements ActionListener,KeyListener
{
JPanel p=new JPanel(new GridLayout(5,4));
Vector b=new Vector();
JTextField result=new JTextField("0");
String s1,s2,c;
double d1,d2,d,num1,num2,num;
boolean isd,end,add,sub,mul,div;
cal()
{
super("Calculator");
b.addElement(new JButton("7"));b.addElement(new JButton("8"));b.addElement(new JButton("9"));b.addElement(new JButton("+"));
b.addElement(new JButton("4"));b.addElement(new JButton("5"));b.addElement(new JButton("6"));b.addElement(new JButton("-"));
b.addElement(new JButton("1"));b.addElement(new JButton("2"));b.addElement(new JButton("3"));b.addElement(new JButton("*"));
b.addElement(new JButton("0"));b.addElement(new JButton("."));b.addElement(new JButton("="));b.addElement(new JButton("/"));
b.addElement(new JButton());b.addElement(new JButton());b.addElement(new JButton("back"));b.addElement(new JButton("c"));
for(int k=-1,i=1;i<=20;i++)
{
p.add((JButton)b.elementAt(++k));
((JButton)b.elementAt(k)).addActionListener(this);
}
add(result,"North");
add(p,"Center");
addWindowListener(new WinApt());
pack();
setResizable(false);
this.requestFocus(true);
addKeyListener(this);
}
public void keyTyped(KeyEvent e){}
public void keyReleased(KeyEvent e){}
public void keyPressed(KeyEvent e){
int kc=e.getKeyCode();
switch(kc){
case 48:
case 96:number(0);break;
case 49:
case 97:number(1);break;
case 50:
case 98:number(2);break;
case 51:
case 99:number(3);break;
case 52:
case 100:number(4);break;
case 53:
case 101:number(5);break;
case 54:
case 102:number(6);break;
case 55:
case 103:number(7);break;
case 56:
case 104:number(8);break;
case 57:
case 105:number(9);break;
case 43:
case 107:sign(1);break;
case 45:
case 109:sign(2);break;
case 42:
case 106:sign(3);break;
case 47:
case 111:sign(4);break;
case 10:getResult();break;
case 46:
case 110:nPoint();break;//小数点
case 8:back();break;//回车
case 27:clear();break;//ESC 清除
default:break;
}
}

public void actionPerformed(ActionEvent e)
{

String s=((JButton)e.getSource()).getLabel();
if(s.equals("+")){
sign(1);
}else if(s.equals("-")){
sign(2);
}else if(s.equals("*")){
sign(3);
}else if(s.equals("/")){
sign(4);
}else if(s.equals("c")){
clear();
}else if(s.equals("back")){
back();
}else if(s.equals("=")){
getResult();
}else if(s.equals(".")){
nPoint();
}else{
int lbnum=Integer.parseInt(s);
number(lbnum);
}

}
void number(int i) //数值
{
String s=Integer.toString(i);
if(result.getText().equals("0")){
result.setText(s);
}else{
result.setText(result.getText()+s);
}
this.requestFocus(true);

}
void sign(int i){ //运算符
num1=Double.valueOf(result.getText()).doubleValue();
result.setText("0");
if(i==1){
add=true;
sub=false;
mul=false;
div=false;
}else if(i==2){
sub=true;
add=false;
mul=false;
div=false;
}else if(i==3){
mul=true;
add=false;
sub=false;
div=false;
}else{
div=true;
add=false;
sub=false;
mul=false;
}
this.requestFocus(true);
}
void getResult(){ //算的结果
num2=Double.valueOf(result.getText()).doubleValue();
if(add==true){
num=num1+num2;
}else if(sub==true){
num=num1-num2;
}else if(mul==true){
num=num1*num2;
}else{
num=num1/num2;
}
result.setText(""+num);
this.requestFocus(true);
}

void nPoint(){ //加小数点
result.setText(result.getText()+".");
}

void back(){
result.setText(result.getText().substring(0,result.getText().length()-1));
}

void clear(){
result.setText("0");
}
public boolean isFocusTraversable(){
return true;
}
}
class WinApt extends WindowAdapter
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}