little error in java code

[saneha]

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class SmallCalcApp implements ActionListener{

JFrame frame;
JLabel firstOperand, secondOperand, answer;
JTextField op1, op2, ans;
JButton plus, mul;

public void initGUI(){

frame = new JFrame();

firstOperand = new JLabel("First Operand");
secondOperand = new JLabel ("Second Operand");
answer = new JLabel ("Answer");

op1 = new JTextField (15);
op2 = new JTextField (15);
ans = new JTextField (15);

mul = new JButton ("*");
mul.setPreferredSize(new Dimension(70,25));

plus = new JButton ("+");
plus.setPreferredSize(new Dimension(70,25));

Container con = frame.getContentPane();
con.setLayout(new FlowLayout());

con.add(firstOperand);
con.add(op1);

con.add(secondOperand);
con.add(op2);

con.add(plus);
con.add(ans);

plus.addActionListener(this);
mul.addActionListener(this);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(200,220);
frame.setVisible(true);

}


public SmallCalcApp(){

initGUI();

}

public void actionPerformed(ActionEvent event){

String oper, result;
int num1, num2, res;

if (event.getSource() == plus){

oper = op1.getText();
num1 = Integer.parseInt(oper);

oper = op2.getText();
num2 = Integer.parseInt(oper);

res = num1 + num2 ;

result = res + "";
ans.setText(result);


}

else if (event.getSource() == mul){

oper = op1.getText();
num1 = Integer.parseInt(oper);

oper = op2.getText();
num2 = Integer.parseInt(oper);

res = num1 * num2;

result = res + "";

ans.setText(result);

}
}

public static void main (String args[]){

SmallCalcApp scApp = new SmallCalcApp();

}
}

[Vuhelper]

Code:

Add the multiplication button as well using statement. con.add(mul); Corrected Code as below import java.awt.*; import javax.swing.*; import java.awt.event.*; public class SmallCalcApp implements ActionListener{ JFrame frame; JLabel firstOperand, secondOperand, answer; JTextField op1, op2, ans; JButton plus, mul; public void initGUI(){ frame = new JFrame(); firstOperand = new JLabel("First Operand"); secondOperand = new JLabel ("Second Operand"); answer = new JLabel ("Answer"); op1 = new JTextField (15); op2 = new JTextField (15); ans = new JTextField (15); mul = new JButton ("*"); mul.setPreferredSize(new Dimension(70,25)); plus = new JButton ("+"); plus.setPreferredSize(new Dimension(70,25)); Container con = frame.getContentPane(); con.setLayout(new FlowLayout()); con.add(firstOperand); con.add(op1); con.add(secondOperand); con.add(op2); con.add(mul); /*Add the multiplication button to container as well*/ con.add(plus); con.add(ans); plus.addActionListener(this); mul.addActionListener(this); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(200,220); frame.setVisible(true); } public SmallCalcApp(){ initGUI(); } public void actionPerformed(ActionEvent event){ String oper, result; int num1, num2, res; if (event.getSource() == plus){ oper = op1.getText(); num1 = Integer.parseInt(oper); oper = op2.getText(); num2 = Integer.parseInt(oper); res = num1 + num2 ; result = res + ""; ans.setText(result); } else if (event.getSource() == mul){ oper = op1.getText(); num1 = Integer.parseInt(oper); oper = op2.getText(); num2 = Integer.parseInt(oper); res = num1 * num2; result = res + ""; ans.setText(result); } } public static void main (String args[]){ SmallCalcApp scApp = new SmallCalcApp(); } }