calculator.java

double link list code

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;

public class calculator extends Applet implements ActionListener
{
     int flag=0;
     double x;
     String s=new String("");
     Panel p1,p2,p3;
     TextField text1;
     Button bclear,beq,badd,bsubtract;
     Button[] b=new Button[10];

     public void init()
     {
     p1=new Panel();p2=new Panel();p3=new Panel();
     setLayout(new FlowLayout());
     p1.setLayout(new FlowLayout());
     p2.setLayout(new GridLayout(4,3));
     p3.setLayout(new GridLayout(4,1));
     text1=new TextField(12);
     bclear=new Button("Clear");


     p1.add(text1);p1.add(bclear);
     bclear.addActionListener(this);
     for(int i=0;i<10;i++)
     {
     b[i]=new Button(Integer.toString(i));
     } //for
     beq=new Button("=");


     for(int i=0;i<10;i++)
     {
      p2.add(b[i]);
      b[i].addActionListener(this);
     }
     p3.add(beq);
     beq.addActionListener(this);


    // badd=new Button("+");
     bsubtract=new Button("-");

    // p2.add(badd);
     p2.add(bsubtract);

    //badd.addActionListener(this);
     bsubtract.addActionListener(this);

     add(p1);
     add(p2);
     add(p3);
     }


     public void actionPerformed(ActionEvent e)
     {
     for(int i=0;i<10;i++)
       {
        if(e.getSource()==b[i]){
          s=s+e.getActionCommand();
          text1.setText(s);
          break;
       }
     }
    if(e.getSource()==badd)
	   {
	    x=Double.parseDouble(s);
       flag=1;
       text1.setText("");
       s="";
	   }
    if(e.getSource()==bsubtract)
	  {
	  x=Double.parseDouble(s);
     flag=2;
     text1.setText("");
     s="";
	  }


     if(e.getSource()==bclear)
     {
     text1.setText("");
     s="";
     flag=0;
     }

//calculator
    if(e.getSource()==beq)
     {
      switch(flag)
      {
         case 1:
         {
         x=Double.parseDouble(s)+x;
         String s=String.valueOf(x);
         text1.setText(s);break;
      }

         case 2:
         {
         x=x-Double.parseDouble(s);
         String s=String.valueOf(x);
         text1.setText(s);break;
         } //case

      } //switch
     } //if
   } //init
} //class