java实现简单计算器

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;
import javax.swing.border.*;

import java.util.LinkedList;       //工具包
import java.text.NumberFormat;     //文本包

public class Calculator extends Frame implements ActionListener       //计算器类
{
 JTextField result;
 NumberButton numberButton[];
 OperatorButton operatorButton[];
 
 Button radixpoint,positiveminus,backspace,reciprocal,equal,clear; //声明成员变量
       //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;
 String operator[]={"+","-","*","/"};
 
 LinkedList linklist;
 boolean pressequal=false;
 
 public Calculator()          //构造方法
 {
  super("计算器");
     linklist=new LinkedList();
  numberButton=new NumberButton[10];
 
  for(int i=0;i<=9;i++)
  {
   numberButton[i]=new NumberButton(i);
   numberButton[i].addActionListener(this);
  }
 
  operatorButton=new OperatorButton[4];
  for(int i=0;i<4;i++)
  {
   operatorButton[i]=new OperatorButton(operator[i]);
   operatorButton[i].addActionListener(this);
  }
 
  radixpoint=new Button(".");
  positiveminus=new Button("+/-");
  backspace=new Button("CE");
  reciprocal=new Button("1/x");
  equal=new Button("=");
  clear=new Button("C");
 
  radixpoint.setForeground(Color.red);
  positiveminus.setForeground(Color.red);
  backspace.setForeground(Color.red);
  reciprocal.setForeground(Color.red);
  equal.setForeground(Color.red);
  clear.setForeground(Color.red);
 
  radixpoint.addActionListener(this);
  positiveminus.addActionListener(this);
  backspace.addActionListener(this);
  reciprocal.addActionListener(this);
  equal.addActionListener(this);
  clear.addActionListener(this);
 
  result=new JTextField(10);
  result.setHorizontalAlignment(JTextField.RIGHT);
  result.setForeground(Color.black);
  result.setBackground(Color.white);
  result.setFont(new Font("TimesRoman",Font.PLAIN,14));
  result.setBorder(new SoftBevelBorder(BevelBorder.LOWERED));
  result.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(backspace);
  panel.add(clear);
 
  panel.add(numberButton[4]);
  panel.add(numberButton[5]);
  panel.add(numberButton[6]);
  panel.add(operatorButton[0]);
  panel.add(operatorButton[2]);
 
  panel.add(numberButton[7]);
  panel.add(numberButton[8]);
  panel.add(numberButton[9]);
  panel.add(operatorButton[1]);
  panel.add(operatorButton[3]);
 
  panel.add(numberButton[0]);
  panel.add(positiveminus);
  panel.add(reciprocal);
  panel.add(radixpoint);
  panel.add(equal);
 
  add(result,"North");
  add(panel,"Center");
 
  addWindowListener(new WindowAdapter()
      {
       public void windowClosing(WindowEvent e)
       {
        System.exit(0);
       }
      });
 
  setSize(270,200);
  setLocation(300,230);
  setVisible(true);
 }
 
 
 public void actionPerformed(ActionEvent e)   //按钮的单击事件处理方法
 {
  if(e.getSource() instanceof NumberButton)      //数字按钮
      {
        NumberButton b=(NumberButton)e.getSource();
         if(linklist.size()==0)
          {
            int number=b.getNumber();        
            linklist.add(""+number);             
            result.setText(""+number);
            pressequal=false;
          }
      
         else if(linklist.size()==1&&pressequal==false)
         {
           int number=b.getNumber();
             String num=(String)linklist.getFirst();
             String s=num.concat(""+number);   
             linklist.set(0,s);
             result.setText(s);
         }
            else if(linklist.size()==1&&pressequal==true)
          {
             int number=b.getNumber();
             linklist.removeFirst();
             linklist.add(""+number);               
             pressequal=false;
             result.setText(""+number);
          }
         else if(linklist.size()==2)              
          {
             int number=b.getNumber();         
             linklist.add(""+number);             
                                            
             result.setText(""+number);
          }
         else if(linklist.size()==3)              
          {
             int number=b.getNumber();
             String num=(String)linklist.getLast();
             String s=num.concat(""+number);   
             linklist.set(2,s);
             result.setText(s);
          }
        }
     else if(e.getSource() instanceof OperatorButton)  //操作按钮
     {
         OperatorButton b=(OperatorButton)e.getSource();
         if(linklist.size()==1)
          {
             String fuhao=b.getOperator();
         
             linklist.add(fuhao);              
          }
         else if(linklist.size()==2)
          {
             String fuhao=b.getOperator();
             linklist.set(1,fuhao);           
          }
         else if(linklist.size()==3)
          {
             String fuhao=b.getOperator();
             String number1=(String)linklist.getFirst();
             String number2=(String)linklist.getLast();
             String operator=(String)linklist.get(1);
             try
             {
                double n1=Double.parseDouble(number1);
                double n2=Double.parseDouble(number2);
                double n=0;
                if(operator.equals("+"))
                {
                   n=n1+n2;
                }
                else if(operator.equals("-"))
                {
                   n=n1-n2;
                }
                else if(operator.equals("*"))
                {
                   n=n1*n2;
                }
                else if(operator.equals("/"))
                {
                   n=n1/n2;
                }
                linklist.clear();
                linklist.add(""+n);                 
                linklist.add(fuhao);                
                result.setText(""+n);
             }
            catch(Exception ee)
             {
             }
          }
      }
     else if(e.getSource()==equal)     //等号按钮
     {
         pressequal=true;
         if(linklist.size()==1||linklist.size()==2)                     
         {
            String num=(String)linklist.getFirst();
            result.setText(""+num);
         }
         else if(linklist.size()==3)
         {
            String number1=(String)linklist.getFirst();
            String number2=(String)linklist.getLast();
            String operator=(String)linklist.get(1);
            try
            {
                double n1=Double.parseDouble(number1);
                double n2=Double.parseDouble(number2);
                double n=0;
                if(operator.equals("+"))
                {
                   n=n1+n2;
                }
                else if(operator.equals("-"))
                {
                   n=n1-n2;
                }
                else if(operator.equals("*"))
                {
                   n=n1*n2;
                }
                else if(operator.equals("/"))
                {
                   n=n1/n2;
                }
                result.setText(""+n);
                linklist.set(0,""+n);
                linklist.removeLast();
                linklist.removeLast();
           
            }
            catch(Exception ee)
            {
            }
        }
    }
    else if(e.getSource()==radixpoint)          //小数点按钮
    {
         if(linklist.size()==0)
         {
             pressequal=false;
         }
         else if(linklist.size()==1)                             
         {
            String dot=radixpoint.getLabel();           
            String num=(String)linklist.getFirst();
            String s=null;
            if(num.indexOf(dot)==-1)                   
            {
                s=num.concat(dot);
                linklist.set(0,s);                
            }
            else
            {
                s=num;
            }
            linklist.set(0,s);
            result.setText(s);
         }
      
         else if(linklist.size()==3)
         {
            String dot=radixpoint.getLabel();           
            String num=(String)linklist.getLast();
            String s=null;
            if(num.indexOf(dot)==-1)
            {
                s=num.concat(dot);
                linklist.set(2,s);
            }
            else
            {
                s=num;
            }
            result.setText(s);
        }
       }
       else if(e.getSource()==backspace)           //退格按钮
    {
        if(linklist.size()==1)                             
        {
            String num=(String)linklist.getFirst();
            if(num.length()>=1)
            {
               num=num.substring(0,num.length()-1);
               linklist.set(0,num);                
               result.setText(num);
            }
            else
            {
               linklist.removeLast();                
               result.setText("0");
            }
        }
        else if(linklist.size()==3)
        {
            String num=(String)linklist.getLast();
            if(num.length()>=1)
            {
                num=num.substring(0,num.length()-1);
                linklist.set(2,num);                
                result.setText(num);
            }
            else
            {
               linklist.removeLast();                
               result.setText("0");
            }
        } 
    }
    else if(e.getSource()==positiveminus)            //正负号按钮
    {
         if(linklist.size()==1)
         {
              String number1=(String)linklist.getFirst();
              try
              {
                  double d=Double.parseDouble(number1);
                  d=-1*d;
                  String str=String.valueOf(d);
               linklist.set(0,str);
               result.setText(str);
              }
           catch(Exception ee)
              {
              }
          }
       else if(linklist.size()==3)
       {
           String number2=(String)linklist.getLast();
           try
           {
                double d=Double.parseDouble(number2);
                d=-1*d;
                String str=String.valueOf(d);
                linklist.set(2,str);
                result.setText(str);
           }
           catch(Exception ee)
           {
           }
       }
     }
     else if(e.getSource()==reciprocal)           //求倒数按钮
     {
        if(linklist.size()==1||linklist.size()==2)
        {
           String number1=(String)linklist.getFirst();
           try
           {
                double d=Double.parseDouble(number1);
                d=1.0/d;
                String str=String.valueOf(d);
                linklist.set(0,str);
                result.setText(str);
           }
           catch(Exception ee)
           {
           }
       }
       else if(linklist.size()==3)
       {
           String number2=(String)linklist.getLast();
           try
           {
                double d=Double.parseDouble(number2);
                d=1.0/d;
                String str=String.valueOf(d);
                linklist.set(0,str);
                result.setText(str);
           }
           catch(Exception ee)
           {
           }
        }
     }
     else if(e.getSource()==clear)                 //清零按钮
     {
         pressequal=false;
         result.setText("0");
         linklist.clear();
     }
 }
 
  public static void main(String args[])
  {
   new Calculator();
  }
 }

class NumberButton extends Button        //数字按钮类
{
 int number;
 public NumberButton(int number)     //构造方法
 {
  super(""+number);
  this.number=number;
  setForeground(Color.blue);
 }
 public int getNumber()
 {
  return number;
 }
}

class OperatorButton extends Button      //运算符号按钮类
{
 String operator;
 public OperatorButton(String operator)           //构造方法
 {
  super(operator);
  this.operator=operator;
  setForeground(Color.red);
 }
 public String getOperator()
 {
  return operator;
 }
}