SIMPLE CALCULATOR IN JAVA USING GUI

import java.awt.*;

import java.awt.event.*;

class CalcFrame extends Frame implements ActionListener

{

     Button bNum[]=new Button[10];

     Button bAdd,bSub,bMul,bDiv,bEql,bClr,b00;

     TextField tScr;

     String opn="";

     int prv,cur;

     CalcFrame()

     {

           super("Calculator");

           setSize(250,350);

           setLocation(300,200);

           setResizable(false);

           for(int i=0;i<10;i++)

           {

                bNum[i]=new Button(String.valueOf(i));

                bNum[i].setFont(new Font("lucida console",Font.PLAIN,18));

                bNum[i].setBackground(new Color(180,180,180));

           }            

           bAdd=new Button("+");

           bAdd.setFont(new Font("lucida console",Font.PLAIN,18));

           bAdd.setBackground(new Color(170,170,255));

           bSub=new Button("-");

           bSub.setFont(new Font("lucida console",Font.PLAIN,18));

           bSub.setBackground(new Color(170,170,255));

           bMul=new Button("*");

           bMul.setFont(new Font("lucida console",Font.PLAIN,18));

           bMul.setBackground(new Color(170,170,255));

           bDiv=new Button("/");

           bDiv.setFont(new Font("lucida console",Font.PLAIN,18));

           bDiv.setBackground(new Color(170,170,255));

           bEql=new Button("=");

           bEql.setFont(new Font("lucida console",Font.PLAIN,18));

           bEql.setBackground(new Color(255,255,170));

           bClr=new Button("Clr");

           bClr.setFont(new Font("lucida console",Font.PLAIN,18));

           bClr.setBackground(new Color(255,180,180));

          

           b00=new Button("00");

           b00.setFont(new Font("lucida console",Font.PLAIN,18));

           b00.setBackground(new Color(180,180,180));

          

           tScr=new TextField();

           tScr.setEditable(false);

           tScr.setFont(new Font("lucida console",Font.BOLD|Font.ITALIC,35));

           tScr.setBackground(Color.black);

           tScr.setForeground(Color.white);

          

           setLayout(new BorderLayout(5,5));

          

           add(tScr,BorderLayout.NORTH);

          

           Panel p=new Panel();

           p.setLayout(new GridLayout(5,4,5,5));

           p.add(new Label());

           p.add(new Label());

           p.add(new Label());

           p.add(bClr);

       

           p.add(bNum[7]);

           p.add(bNum[8]);

           p.add(bNum[9]);

           p.add(bAdd);

                 

           p.add(bNum[4]);

           p.add(bNum[5]);

           p.add(bNum[6]);

           p.add(bSub);

            

           p.add(bNum[1]);

           p.add(bNum[2]);

           p.add(bNum[3]);

           p.add(bMul);

           p.add(bNum[0]);

           p.add(b00);

           p.add(bEql);

           p.add(bDiv);

           add(p,BorderLayout.CENTER);

           for(int i=0;i<10;i++)

                bNum[i].addActionListener(this);

           b00.addActionListener(this);

           bAdd.addActionListener(this);

           bSub.addActionListener(this);

           bMul.addActionListener(this);

           bDiv.addActionListener(this);

           bEql.addActionListener(this);

           bClr.addActionListener(this);

           addWindowListener(new CalcWndAdapter());

     }

     public Insets getInsets()

     {

           return new Insets(40,10,10,10);

     }

     public void actionPerformed(ActionEvent ae)

     {

           String op=((Button)(ae.getSource())).getLabel();

           switch(op)

           {

                case "+":

                                if(opn=="")

                                {

                                     prv=cur;

                                     cur=0;

                                }

                                else

                                     evaluate();

                                opn="+";

                                break;

                    

                case "-":

                                if(opn=="")

                                {

                                     prv=cur;

                                     cur=0;

                                }

                                else

                                     evaluate();

                                opn="-";

                                break;

                    

                case "*":

                                if(opn=="")

                                {

                                     prv=cur;

                                     cur=0;

                                }

                                else

                                     evaluate();

                                opn="*";

                                break;

                    

                case "/":

                                if(opn=="")

                                {

                                     prv=cur;

                                     cur=0;

                                }

                                else

                                     evaluate();

                                opn="/";

                                break;

                               

                case "=":

                                if(opn!="")

                                {

                                     evaluate();

                                     opn="=";

                                }

                                break;

                case "00":

                                cur*=100;

                                tScr.setText(cur+"");

                                break;

                case "Clr":

                                cur=prv=0;

                                opn="";

                                tScr.setText("0");

                                break;

                default:

                                int n;

                                try

                                {

                                     n=Integer.parseInt(op);

                                }

                                catch(Exception e)

                                {

                                     n=0;

                                }

                                cur=cur*10+n;

                                tScr.setText(cur+"");

               

           }

     }

    

     void evaluate()

     {

           switch(opn)

           {

                case"+":

                     prv+=cur;break;

                    

                case"-":

                     prv-=cur;break;

                    

                case"*":

                     prv*=cur;break;

                    

                case"/":

                     prv/=cur;break;

           }

           tScr.setText(prv+"");

           cur=0;

     }

}

class CalcWndAdapter extends WindowAdapter

{

     public void windowClosing(WindowEvent we)

     {

           System.exit(0);

     }

}

class calc

{

     public static void main(String arg[])

     {

           CalcFrame cf=new CalcFrame();

           cf.setVisible(true);

     }

}