本人正在做一个计算器，其中能响应键盘事件，加减乘除怎么实现？

Question

加就直接用+
取出a,取出b.int i=Integer.parse(a)+Integer.parse(b);

Answer 1

可以的啊：
jTextField.addKeyListener(new KeyAdapter(){
        public void keyPressed(KeyEvent e){
            if (e.getKeyCode()==KeyEvent.VK_ADD){
                System.out.println(true);
            }
        }
    });试试，^_^

Answer 2

不要用键盘事件,用普通监听器,然后对该按钮加个shortcut,如同"+"button就叫个VK_ADD

Answer 3

jTextField.addKeyListener(new KeyAdapter(){
        public void keyPressed(KeyEvent e){
            if (e.getKeyCode()==KeyEvent.VK_ADD){
                System.out.println(true);
            }
        }
    });

Answer 4

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.util.LinkedList;
import java.text.NumberFormat;
public class ComputerPad extends Frame implements ActionListener 
{
   NumberButton numberButton[];                  
   OperationButton oprationButton[];             
   Button 小数点按钮,正负号按钮,退格按钮,
          求倒数按钮,等号按钮,清零按钮;
   Panel panel;                                 
   JTextField resultShow;                        
   String 运算符号[]={"+","-","*","/"};
   LinkedList 链表;                              
   boolean  是否按下等号=false;                  
  
 public ComputerPad()
   {
     super("计算器");
     链表=new LinkedList();
     numberButton=new NumberButton[10];          
     for(int i=0;i<=9;i++)
        {
          numberButton[i]=new NumberButton(i);
          numberButton[i].addActionListener(this);
        }
     oprationButton=new OperationButton[4];    
     for(int i=0;i<4;i++)
        {
          oprationButton[i]=new OperationButton(运算符号[i]);
          oprationButton[i].addActionListener(this);
        }
     小数点按钮=new Button(".");
     正负号按钮  =new Button("+/-"); 
     等号按钮=new Button("=");
     求倒数按钮=new Button("1/x");
     退格按钮=new Button("退格");
     清零按钮=new Button("C");
     清零按钮.setForeground(Color.red);
     退格按钮.setForeground(Color.red);
     等号按钮.setForeground(Color.red);
     求倒数按钮.setForeground(Color.blue);
     正负号按钮.setForeground(Color.blue);
     小数点按钮.setForeground(Color.blue);
     退格按钮.addActionListener(this);
     清零按钮.addActionListener(this);
     等号按钮.addActionListener(this);
     小数点按钮.addActionListener(this);
     正负号按钮.addActionListener(this);
     求倒数按钮.addActionListener(this);
     resultShow=new JTextField(10);
     resultShow.setHorizontalAlignment(JTextField.RIGHT);
     resultShow.setForeground(Color.blue);
     resultShow.setFont(new Font("TimesRoman",Font.PLAIN,14));
     resultShow.setBorder(new SoftBevelBorder(BevelBorder.LOWERED));
     resultShow.setBackground(Color.white); 
     resultShow.setEditable(false);
     panel=new Panel();                                             
     panel.setLayout(new GridLayout(4,5)); 
     
     panel.add(numberButton[1]);
     panel.add(numberButton[2]);
     panel.add(numberButton[3]);
     panel.add(oprationButton[0]);
     panel.add(清零按钮);
     
     panel.add(numberButton[4]);
     panel.add(numberButton[5]);
     panel.add(numberButton[6]);
     panel.add(oprationButton[1]);
     panel.add(退格按钮);
     
     panel.add(numberButton[7]);
     panel.add(numberButton[8]);
     panel.add(numberButton[9]);
     panel.add(oprationButton[2]);
     panel.add(求倒数按钮);
     
     panel.add(numberButton[0]);
     panel.add(正负号按钮);
     panel.add(小数点按钮);
     panel.add(oprationButton[3]);
     panel.add(等号按钮);
     add(panel,BorderLayout.CENTER);
     add(resultShow,BorderLayout.NORTH);
    
     addWindowListener(new WindowAdapter()
                    { public void windowClosing(WindowEvent e)
                       {
                         System.exit(0);
                       }
                    });
    setVisible(true);
    setBounds(100,50,240,180);
    setResizable(false);
    validate();
   }

Answer 5

public void actionPerformed(ActionEvent e)
   {
   
    if(e.getSource() instanceof NumberButton)   
     {
       NumberButton b=(NumberButton)e.getSource();
        if(链表.size()==0) 
         {
           int number=b.getNumber();          
           链表.add(""+number);               
           resultShow.setText(""+number);
           是否按下等号=false;
         }
        
        else if(链表.size()==1&&是否按下等号==false)
         {
           int number=b.getNumber();
           String num=(String)链表.getFirst();
           String s=num.concat(""+number);     
           链表.set(0,s);
           resultShow.setText(s);
         }
        else if(链表.size()==1&&是否按下等号==true)
         {
           int number=b.getNumber();
            链表.removeFirst();
           链表.add(""+number);                 
           是否按下等号=false;
           resultShow.setText(""+number);
         }
        else if(链表.size()==2)                
         {
           int number=b.getNumber();           
           链表.add(""+number);               
                                              
           resultShow.setText(""+number);
         }
        else if(链表.size()==3)                
         {
           int number=b.getNumber();
           String num=(String)链表.getLast();
           String s=num.concat(""+number);     
           链表.set(2,s);
           resultShow.setText(s);
         }
     }
   else if(e.getSource() instanceof OperationButton) 
     {
       OperationButton b=(OperationButton)e.getSource();
       if(链表.size()==1)
         {
           String fuhao=b.get运算符号();
           
           链表.add(fuhao);                
         }
       else if(链表.size()==2)
         {
           String fuhao=b.get运算符号();
           链表.set(1,fuhao);             
         }
       else if(链表.size()==3)
         {
           String fuhao=b.get运算符号();
           String number1=(String)链表.getFirst();
           String number2=(String)链表.getLast();
           String 运算符号=(String)链表.get(1);
           try
            {
               double n1=Double.parseDouble(number1);
               double n2=Double.parseDouble(number2);
               double n=0;
               if(运算符号.equals("+"))
                 {
                   n=n1+n2;
                 }
               else if(运算符号.equals("-"))
                 {
                   n=n1-n2;
                 }
               else if(运算符号.equals("*"))
                 {
                   n=n1*n2;
                 }
               else if(运算符号.equals("/"))
                 {
                   n=n1/n2;
                 }
               链表.clear();
               链表.add(""+n);                   
               链表.add(fuhao);                  
               resultShow.setText(""+n);
            }
          catch(Exception ee)
            {
            }
         }
     }
   else if(e.getSource()==等号按钮) 
     {
        是否按下等号=true;
        if(链表.size()==1||链表.size()==2)                       
         {
           String num=(String)链表.getFirst();
           resultShow.setText(""+num);
         }
        else if(链表.size()==3)
         {
           String number1=(String)链表.getFirst();
           String number2=(String)链表.getLast();
           String 运算符号=(String)链表.get(1);
           try
            {
               double n1=Double.parseDouble(number1);
               double n2=Double.parseDouble(number2);
               double n=0;
               if(运算符号.equals("+"))
                 {
                   n=n1+n2;
                 }
               else if(运算符号.equals("-"))
                 {
                   n=n1-n2;
                 }
               else if(运算符号.equals("*"))
                 {
                   n=n1*n2;
                 }
               else if(运算符号.equals("/"))
                 {
                   n=n1/n2;
                 }
               resultShow.setText(""+n);
               链表.set(0,""+n);
               链表.removeLast();  
               链表.removeLast();  
            
            }
          catch(Exception ee)
            {
            }
         }
     }

Answer 6

operationButton[0].registerKeyboardAction(new ActionListener(){
   public void actionPerformed(ActionEvent e) {
      operationButton[0].doClick();
   }
}, KeyStroke.getKeyStroke(KeyEvent.VK_ADD, 0), JComponent.WHEN_IN_FOCUSED_WINDOW);
当焦点在窗口任何地方, 按下+, 就会发送一个操作+按钮的点击事件.

Answer 7

楼上的你给别人写了那么多,几句注释也没有,你叫别人咋看?
其实主要有两点,第一点就是监听器,建议使用KeyAdapter类(适配器);第二点就是如何将字符串转化为int型:
1、键盘监听器及实现：import java.awt.Button;
import java.awt.event.KeyEvent;
import java.awt.event.KeyAdapter;
public class Test2 {
/*这里只写如何向按钮添加监听器，并用KeyAdapter作出相应事件*/
public Test2(){
Button myButton = new Button();
myButton.addKeyListener(new Adapter());//添加监听器
}

/**
 * 此类用于处理键盘事件,还可以覆盖很多方法，详见API
 * */
class Adapter extends KeyAdapter{
public void keyPressed(KeyEvent e){
e.getKeyChar();//接受键盘输入的字符
}
}
}2、将字符串转化为int型
String.valueOf(int i),这是一个静态方法
另外还有一个方法可以将int型转化为字符串型
Integer.parseInt(String s), 这也是一个静态方法

Answer 8

water2004(@-@) 
标识符难道可以用汉字表示吗？
汉字最高位是1 而字母最高位是0
java不是只允许以字母开头的标识符吗？

Answer 9

/**  CalculatorApplet  计算器
 * 操作数?  (第一位) 完成后标志位F;  (非第一) String的连接
 *  "-"  ?    (负号) 完成后标志位F;  (减号)   运算符保存 
 *
 * 是运算符:  A+B-C  (输入"-")?   (A+B)运算并显示结果.
 * 保持"-"为下次运算做准备
 * @version 1.20 27 Jun 1998
 * @author Cay Horstmann
 */import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class CalculatorApplet extends JApplet
{  
   public void init()
   {  Container contentPane = getContentPane();  // Returns the contentPane object for this applet. 
      contentPane.add(new CalculatorPanel());
   }
}class CalculatorPanel extends JPanel implements ActionListener
{  
   private JTextField display;
   private double arg = 0;  // 运算结果存储区
   private String op = "=";
   private boolean start = true;
   
   public CalculatorPanel()
   {  
      setLayout(new BorderLayout());
      
      display = new JTextField("0");
      display.setEditable(false);
      add(display, "North");
      
      JPanel p = new JPanel();  // 按钮面板布局
      p.setLayout(new GridLayout(4, 4));
      
      String buttons = "789/456*123-0.=+";
      for (int i = 0; i < buttons.length(); i++) 
         addButton(p, buttons.substring(i, i + 1));      
      /*
         从i开始, 到i结束. 每次返回一个字符作为创建要素
         返回是该字符串子串的新字符串。 
     子串开始于指定的 beginIndex ，
     且扩展到索引为 endIndex - 1 的位置。
      */            
      add(p, "Center");
   }   private void addButton(Container c, String s)  // c = JPanel
   {  // 创建新按钮, 放置到面板, 添加监听器, 一气呵成   
      JButton b = new JButton(s);
      c.add(b);
      b.addActionListener(this);
   }
   
   public void actionPerformed(ActionEvent evt)
   {  
      String s = evt.getActionCommand();  // 返回与该动作相关的命令名。
      
      if ('0' <= s.charAt(0) && s.charAt(0) <= '9' 
         || s.equals("."))
      {  // 操作数  
        if (start) 
        {  // 操作数的第一位 
         display.setText(s);
         start = false;
       }
         else 
         {  // 非操作数的第一位  
          display.setText(display.getText() + s);
         }
      }
      
      else  // 是'-'吗?
      {  if (start)
         {  if (s.equals("-")) // 负数处理 
            { 
             display.setText(s); 
             start = false; 
            }
            else op = s;
         }  
         
         else // 开始运算  A+B-C  
         {  calculate(Double.parseDouble
               (display.getText()));  // A+B
               //  有必要判断吗?
       //  display.getText() 是数字吗? 
       //  是: 计算; 不是: 操作符刷新  
            op = s;  // - 运算符保存起, 为下次运算做准备
            start = true;  // 为下一个操作数的输入做准备
         }
      }
   }
   
   public void calculate(double n)
   {  if (op.equals("+")) arg += n; // 运算符是前一次输入的
      else if (op.equals("-")) arg -= n;
      else if (op.equals("*")) arg *= n;
      else if (op.equals("/")) arg /= n;
      else if (op.equals("=")) arg = n;
      
      display.setText("" + arg);  // 显示运算结果
   }
   
}

Answer 10

可以用汉字。还有两个button类没给出。你自己写吧。应该能写出来