// A Sample Java Swing Application
import java.awt.Window;
import java.awt.Color;
import java.awt.Toolkit;
import java.awt.Dimension;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyAdapter;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.CardLayout;
import java.awt.GridBagLayout;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class Calc extends JFrame implements ActionListener
{
JButton addBut, subBut, mulBut, divBut, setBut, extBut;
JTextField txt1, txt2, txt3;
JPanel pan;
public Calc()
{
super("Sample Frame");
setBounds(100,100,300,300);
centerWindow(this);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(mainPanel());
}
public JPanel mainPanel()
{
pan = new JPanel();
pan.setLayout(new GridLayout(6, 2));
pan.add(new JLabel("Enter a value : ", SwingConstants.CENTER));
txt1 = new JTextField();
txt1.requestFocusInWindow();
pan.add(txt1);
txt1.addKeyListener(new MyKeyListener());
pan.add(new JLabel("Enter another value : ", SwingConstants.CENTER));
txt2 = new JTextField();
pan.add(txt2);
txt2.addKeyListener(new MyKeyListener());
pan.add(new JLabel("Result : ", SwingConstants.CENTER));
txt3 = new JTextField();
txt3.setEditable(false);
pan.add(txt3);
addBut = new JButton("Add");
pan.add(addBut);
addBut.addActionListener(this);
subBut = new JButton("Subtract");
pan.add(subBut);
subBut.addActionListener(this);
mulBut = new JButton("Multiply");
pan.add(mulBut);
mulBut.addActionListener(this);
divBut = new JButton("Divide");
pan.add(divBut);
divBut.addActionListener(this);
setBut = new JButton("Reset");
pan.add(setBut);
setBut.addActionListener(this);
extBut = new JButton("Exit");
pan.add(extBut);
extBut.addActionListener(this);
return pan;
}
class MyKeyListener extends KeyAdapter
{
public void keyTyped(KeyEvent ke)
{
char ch = ke.getKeyChar();
if(ch!='0' && ch!='1' && ch!='2' && ch!='3' &&
ch!='4' && ch!='5' && ch!='6' && ch!='7' &&
ch!='8' && ch!='9' && ch!='.' && ch!='-')
ke.consume();
}
}
public void actionPerformed(ActionEvent ae)
{
double val1 = 0.0, val2 = 0.0;
try
{
Object source = ae.getSource();
if(source == extBut)
{
System.exit(0);
}
else if(source == setBut)
{
txt1.setText("");
txt2.setText("");
txt3.setText("");
}
else
{
String str1 = txt1.getText().trim(),
str2 = txt2.getText().trim();
if( isPresent(str1) && isPresent(str2) )
{
val1 = Double.parseDouble(str1);
val2 = Double.parseDouble(str2);
if(source == addBut)
{
txt3.setText(String.valueOf(val1 + val2));
}
else if(source == subBut)
{
txt3.setText(String.valueOf(val1 - val2));
}
else if(source == mulBut)
{
txt3.setText(String.valueOf(val1 * val2));
}
else if(source == divBut)
{
txt3.setText(String.valueOf(val1 / val2));
}
}
else
{
displayMessage("Please Enter the Values");
}
}
}
catch(NumberFormatException nfe)
{
displayMessage("Please Enter Valid Input Values");
}
catch(Exception e)
{
System.out.println(e);
}
txt1.requestFocusInWindow();
}
public void displayMessage(String message)
{
JOptionPane.showMessageDialog(this, message,
"Request for Input", JOptionPane.INFORMATION_MESSAGE);
}
public boolean isPresent(String str)
{
if(str.length() == 0)
return false;
else
return true;
}
public void centerWindow(Window w)
{
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension d = tk.getScreenSize();
setLocation( (d.width - w.getWidth())/2,
(d.height - w.getHeight())/2 );
}
public static void main(String[] args)
{
new Calc().setVisible(true);
}
}
