Could u guys help me with a calculator program

Question

hi
i'm writing a calculator program for my java class and the code ur about to read actually works but when i click on the keypad i don't get any numbers in the display screen, the textfield
Could u guys have a look at it please:
here we go
import javax.swing.* ;
import java.awt.* ;
import java.awt.event.* ;
public class Calculator extends JFrame implements ActionListener {
public boolean firstDigit;
public int temp1 = 0;
public int temp = 0;
public int result = 0;
public String opr = "";
JTextField tf= new JTextField ("",20) ;           //sets the display initially at 0
//tf.setEditable (false) ; this doesn't work
JPanel pan = new JPanel() ;
JButton bclear= new JButton("C") ;
JButton b0= new JButton("0") ;
JButton badd = new JButton("+") ;
JButton bsub = new JButton("-") ;
JButton bmult = new JButton("x");
JButton bdiv = new JButton("/") ;
JButton bpoint= new JButton(".");
JButton bequal = new JButton("=");
public Calculator (String title) // constructor
super(title)     ;     
pan.add(tf);
for ( int i=1; i<=3; i++)
JButton butt=new JButton(""+i);
butt.addActionListener(this);
pan.add(butt);                }
badd.addActionListener(this);
pan.add(badd);
for ( int i=4; i<=6; i++)
JButton butt=new JButton(""+i);
butt.addActionListener(this);
pan.add(butt);
bsub.addActionListener(this);
pan.add(bsub);
for ( int i=7; i<=9; i++)
JButton butt=new JButton(""+i);
butt.addActionListener(this);
pan.add(butt);
bmult.addActionListener(this);
pan.add(bmult);
bclear.addActionListener(this);
pan.add(bclear);
b0.addActionListener(this);
pan.add(b0);
bpoint.addActionListener(this);
pan.add(bpoint);
bequal.addActionListener(this);
pan.add(bequal);
bdiv.addActionListener(this);
pan.add(bdiv);
//pan.add(new Button(""));
setContentPane(pan) ;
public boolean action(Event e, Object o)
//checks for operator keys
if (e.target == badd)
temp1 = temp;     //to "save" for calculation
opr = "+";
else if (e.target == bsub)
temp1 = temp;
opr = "-";
else if (e.target == bmult)
temp1 = temp;     
opr = "*";
else if (e.target == bdiv)
temp1 = temp;
opr = "/";
else if (e.target == bequal)
result = calculate(temp1,opr,temp);
tf.setText(Integer.toString(result)); //does the calculation
temp= result; //to be able to do an operation on the result
else if (e.target == bclear)
tf.setText("");
temp1 = 0; //resets the temps and display to 0
temp = 0;
else
//numeric buttons
if (firstDigit)
tf.setText( o.toString() );
firstDigit = false;
temp = Integer.parseInt(tf.getText()); //saves the number in a temp
else
tf.setText(tf.getText() + o.toString()); //for numbers longer than 1 digit
temp = Integer.parseInt(tf.getText());
return true;
firstDigit = true; // GET READY FOR NEXT NUMBER
return true;
public int calculate(int num1,String op, int num2 )
// calculate the numbers
int answers = 0;
if (op == "+")
answers = num1 + num2; //does the calculation for +
else if(op == "-")
answers = num1 - num2; //does the calculation for -
else if(op == "/")
if(num2 == 0)
tf.setText("ERROR");//gives error message if dividing by 0
else     
answers = num1 / num2;
else if(op == "*")
answers = num1 * num2; //does the calculation for *
return answers;
public void actionPerformed(ActionEvent e) {
Object source = e.getSource() ;
public static void main(String[] args)     {
try {
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName() );
catch (Exception e) {
System.err.println("impossible to use system setting : " + e ); }
Calculator fen = new Calculator("CALCULATOR");
fen.setSize(235, 300);
fen.setVisible(true);
fen.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Answer 1

I Hope this would help you.
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?lngWId=2&txtCodeId=2275
Thanks,
Vikas Karwal
[email protected]