Sushil's Blog on Programming Tutorials

SimpleCalculator.java

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;

class SetCalculator extends JFrame implements ActionListener{
JLabel label1, label2, label3;

JButton btnPlus, btnMinus, btnMultiply, btnClear;
JTextField txtField1, txtField2, txtField3;

public SetCalculator(){
setLayout(new GridLayout(5,2));
setTitle("Simple Calculator using Swing");
//initializing label
label1 = new JLabel("Number 1 :",JLabel.RIGHT);
label2 = new JLabel("Number 2 :",JLabel.RIGHT);
label3 = new JLabel("Result :",JLabel.RIGHT);

//initializing buttons;
btnPlus = new JButton("+");
btnMinus = new JButton("-");
btnMultiply = new JButton("*");
btnClear = new JButton("Clear");

//adding eventlistener
btnPlus.addActionListener(this);
btnMinus.addActionListener(this);
btnMultiply.addActionListener(this);
btnClear.addActionListener(this);
//initializing textfield
//for(int i = 0; i < 3; i++)
txtField1 = new JTextField();
txtField2 = new JTextField();
txtField3 = new JTextField();

//adding to the frame
add(label1,0);
add(txtField1);
add(label2);
add(txtField2);
add(label3);
add(txtField3);
add(btnPlus);
add(btnMinus);
add(btnMultiply);
add(btnClear);
}//end of constructor


//action listener method
public void actionPerformed(ActionEvent event){
String opt = event.getActionCommand();
int num1, num2, num = 0;
num1 = Integer.parseInt(txtField1.getText());
num2 = Integer.parseInt(txtField2.getText());


if(opt.equals("+"))
num = num1 + num2;
else if(opt.equals("-"))
num = num1 - num2;
else if(opt.equals("*"))
num = num1 * num2;
else if(opt.equals("Clear")){
txtField1.setText("");
txtField2.setText("");
txtField3.setText("");
}
txtField3.setText(Integer.toString(num));

}
}

public class SimpleCalculator {
public static void main(String args[]){
SetCalculator demo = new SetCalculator();
demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
demo.setVisible(true);
demo.setSize(300,500);
}
}