jButtons are driving me crazy

[Tami Hart]

how do I get my buttons to have functionality? the window is set up the way I want it. however, when the user clicks on the calculate button I want it to perform a mathmatical function and then display the results in the payment field.

Please Help

here is my program:

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

class PosMortg1 extends JFrame {

PosMortg1() {
super("Calculate a Mortgage Payment?");
setSize(370, 270);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container pane = getContentPane();
FlowLayout flow = new FlowLayout(FlowLayout.RIGHT);
pane.setLayout(flow);
JPanel row1 = new JPanel();
JLabel amountLabel = new JLabel("How much are you Borrowing?");
row1.add(amountLabel);
JTextField amount = new JTextField(14);
row1.add(amount);
pane.add(row1);
JPanel row2 = new JPanel();
JLabel percentLabel = new JLabel("Enter Percent Rate:");
row2.add(percentLabel);
JTextField percent = new JTextField(14);
row2.add(percent);
pane.add(row2);
JPanel row3 = new JPanel();
JLabel yearsLabel = new JLabel("How Many Years?");
row3.add(yearsLabel);
JTextField years = new JTextField(14);
row3.add(years);
pane.add(row3);
JPanel row4 = new JPanel();
JButton calculate = new JButton("Calculate");
row4.add(calculate);
pane.add(row4);
JPanel row5 = new JPanel();
JLabel paymentLabel = new JLabel("Monthly Payments");
row5.add(paymentLabel);
JTextArea payment = new JTextArea(4, 14);
payment.setLineWrap(true);
payment.setWrapStyleWord(true);
JScrollPane scroll = new JScrollPane(payment,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
row5.add(scroll);
pane.add(row5);
setContentPane(pane);
setVisible(true);
}

public static void main(String[] arguments) {
PosMortg1 mortgage = new PosMortg1();
}
}

[Gregg Bolinger]

I'd say you need to visit Sun's tutorial on Buttons.

JButton button = new JButton("Push Me");
button.addActionListener(new ActionListener()
{
   public void actionPerformed(ActionEvent e)
   {
      //Do your stuff here
   }
});

[Eddie Vanda]

I do not think you need the second last line of your constructor:

setContentPane(pane);

But it probably does not do any harm.

[Gregg Bolinger]

Tami asked:

if I want to use the fields the user fills in How do I call them into the same math equation? I need to use all three in the same math equation.

In your event method you can simply call amount.getText() to get a String of the value entered in the textfield. Keep in mind though that you will then need to convert your String to an Integer to do calculations. Also note that the compile will probably complain that your variables like amount, percent, etc will need to be declared final.
[ July 03, 2004: Message edited by: Gregg Bolinger ]

[Gregg Bolinger]

Here's how I might do it:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
class PosMortg1 extends JFrame 
{
JTextField amount;
JTextField percent;
JTextField years;
JTextArea payment;

PosMortg1() 
{
super("Calculate a Mortgage Payment?");
setSize(370, 270);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container pane = getContentPane();
FlowLayout flow = new FlowLayout(FlowLayout.RIGHT);
pane.setLayout(flow);
JPanel row1 = new JPanel();
JLabel amountLabel = new JLabel("How much are you Borrowing?");
row1.add(amountLabel);
amount = new JTextField(14);
row1.add(amount);
pane.add(row1);
JPanel row2 = new JPanel();
JLabel percentLabel = new JLabel("Enter Percent Rate:");
row2.add(percentLabel);
percent = new JTextField(14);
row2.add(percent);
pane.add(row2);
JPanel row3 = new JPanel();
JLabel yearsLabel = new JLabel("How Many Years?");
row3.add(yearsLabel);
years = new JTextField(14);
row3.add(years);
pane.add(row3);
JPanel row4 = new JPanel();
JButton calculate = new JButton("Calculate");
calculate.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
float amt = Float.valueOf(amount.getText());
float pct = Float.valueOf(percent.getText());
float yrs = Float.valueOf(years.getText());
//Do calculations with floats
float answer = 123.45f; //This is for demo purposes only
payment.setText(String.valueOf(answer));

}
});
row4.add(calculate);
pane.add(row4);
JPanel row5 = new JPanel();
JLabel paymentLabel = new JLabel("Monthly Payments");
row5.add(paymentLabel);
payment = new JTextArea(4, 14);
payment.setLineWrap(true);
payment.setWrapStyleWord(true);
JScrollPane scroll = new JScrollPane(payment,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
row5.add(scroll);
pane.add(row5);
setVisible(true);
}
 
public static void main(String[] arguments) 
{
PosMortg1 mortgage = new PosMortg1();
}
}