import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class jisuanqi extends JFrame implements ActionListener
{
  JTextField displaytext=new JTextField(30);
  String[] keys={"1","2","3","+","4","5","6","-","7","8","9","*","0",".","=","/","C"};
  // modify by andy start
  // JButton[] Button;
  JButton[] buttonList = new JButton[17];
  // modify by andy end
  String numstr1;
  String numstr2;
  char op;
  boolean firstinput=true;
  public jisuanqi()
  {
    // add by andy
    Box bv = Box.createVerticalBox();
    setTitle("我的?算器");
    setSize(260,200);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    GridLayout layout=new GridLayout(3,1,10,10);
   JPanel row1=new JPanel();
   row1.add(displaytext);
   // modify
   //add(row1);
   bv.add(row1);
   // modify
   GridLayout layout1=new GridLayout(4,4,10,10);
   JPanel row2=new JPanel();
   row2.setLayout(layout1);
   for(int index=0;index<16;index++)
   {
     buttonList[index]=new JButton(keys[index]);
     buttonList[index].addActionListener(this);
     buttonList[index].setSize(50,30);
     row2.add(buttonList[index]);
   }
   // modify
   //add(row2);
   bv.add(row2);
   // modify
   JPanel row3=new JPanel();
   // modify by andy start.
   buttonList[16]=new JButton("C");
   // modify by andy end.
   buttonList[16].addActionListener(this);
   row3.add(buttonList[16]);
   // modify
   //add(row3);
   bv.add(row3);
   // modify
   add(bv);
   setVisible(true);
  }
  public void actionPerformed(ActionEvent e)
  {
    String resultstr;
    String str=e.getActionCommand();
    char ch;
    ch=str.charAt(0);
    switch(ch)
    {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
      case '.': if(firstinput)
       {
         numstr1=numstr1+ch;
         displaytext.setText(numstr1);
       }
       else
       {
         numstr2=numstr2+ch;
         displaytext.setText(numstr2);
       }
       break;
      case '+':
      case '-':
      case '*':
      case '/': op=ch;
       firstinput=false;
       break;
      case '=': resultstr=jisuan();
       displaytext.setText(resultstr);
       numstr1=resultstr;
       numstr2="";
       break;
      case 'C': displaytext.setText("0.");
       numstr1="";
       numstr2="";
       break;
      }
    }
    public String jisuan()
    {
      
      try
      {
        double A=  Double.valueOf(numstr1);
        double B=  Double.valueOf(numstr1);
        double result=0.0;
        switch(op)
        {
          case '+': result=A+B;
           break;
         case '-': result=A-B;
         break;
         case '*': result=A*B;
         break;
         case '/': result=A/B;
         break;
       }
       return String.valueOf(result);
     }  
     catch(ArithmeticException e)
     {
       
       return "??"+e.getMessage();
     }
     catch(NumberFormatException e)
     {
    
       if(numstr1.equals(""))
        return "??：第一个数不可用";
       else
        return "??：第二个数不可用";
     }
     catch(Exception e)
     {
       
        return "??";
     }
    
    
  }
  public static void main(String[] args)
  {
    jisuanqi myjisuanqi=new jisuanqi();
  }
}