Caluclator

//Import statements

import java.awt.*;

import java.awt.event.*;

//Class Definition

class Calc extends Frame implements ActionListener, TextListener, FocusListener

{

    //Variabl declaraion

    Label la1,la2,la3;

    TextField te1,te2,te3;

    Button bn1, bn2, bn3, bn4, bn5;

    int y,z,re=0;

    

    public Calc(String title)

    {

        super(title);

        setLayout(new FlowLayout());

        la1=new Label("Number 1:");//Object creation

        la2=new Label("Number 2:");

        la3=new Label("Result     :");

        te1=new TextField(10);

        te1.addFocusListener(this);//Calling the method

        te2=new TextField(10);

        te3=new TextField(10);

        te3.setEditable(false);

        bn1=new Button("Add");

        bn2=new Button("Sub");

        bn3=new Button("Mul");

        bn4=new Button("Div");

        bn5=new Button("Exit");

        bn1.setEnabled(false);

        bn2.setEnabled(false);

        bn3.setEnabled(false);

        bn4.setEnabled(false);

        bn1.addActionListener(this);

        bn2.addActionListener(this);

        bn3.addActionListener(this);

        bn4.addActionListener(this);

        bn5.addActionListener(this);

        te1.addTextListener(this);

        te2.addTextListener(this);

        add(la1);

        add(te1);

        add(la2);

        add(te2);

        add(la3);

        add(te3);

        add(bu1);

        add(bu2);

        add(bu3);

        add(bu4);

        add(bu5);

    }

    public static void main(String args[])//Main function

    {

        Calc c=new Calc("Calculator");

        c.setSize(200,200);

        c.show();

    }

  

    public void actionPerformed(ActionEvent e)//Method definition

    {

        //To Convert string to integer

        x=Integer.parseInt(te1.getText());

        y=Integer.parseInt(te2.getText());

        if(e.getSource()==bu1) //Decision making statement

            re=x+y;

        else if(e.getSource()==bu2)

            re=x-y;

        else if(e.getSource()==bu3)

            re=x*y;

        else if(e.getSource()==bu4)

            re=x/y;

        else if(e.getSource()==bu5)

            System.exit(0);

        te3.setText(String.valueOf(re));

    }

    public void copy()

    {

        x=Integer.parseInt(te1.getText());

        y=Integer.parseInt(te2.getText());

    }

    // © http://students3k.com - Karthikh Venkat

    public void textValueChanged(TextEvent tu)

    {

        if(!te1.getText().equals("")  & (!te2.getText().equals("")))

        {

            bu1.setEnabled(true);

            bu2.setEnabled(true);

            bu3.setEnabled(true);

            bu4.setEnabled(true);

        }

        else

        {

            bu1.setEnabled(false);

            bu2.setEnabled(false);

            bu3.setEnabled(false);

            bu4.setEnabled(false);

        }

    }

    public void focusGained(FocusEvent fe)// method

    {

    

    }

    public void focusLost(FocusEvent fe)

    {

        if(te1.getText().equals(""))

        {

            javax.swing.JOptionPane.showMessageDialog(this,"The field should not be left blank");

        }

    }

 

}