Thread: java.lang.NullPointerException

I tried to debug but I cannot find which object is null ( I am using JGrasp)

here is the exception:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at RectangleProgram$CalculateButtonHandler.actionPerformed(RectangleProgram.java:61)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
	at java.awt.Component.processMouseEvent(Component.java:6504)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
	at java.awt.Component.processEvent(Component.java:6269)
	at java.awt.Container.processEvent(Container.java:2229)
	at java.awt.Component.dispatchEventImpl(Component.java:4860)
	at java.awt.Container.dispatchEventImpl(Container.java:2287)
	at java.awt.Component.dispatchEvent(Component.java:4686)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
	at java.awt.Container.dispatchEventImpl(Container.java:2273)
	at java.awt.Window.dispatchEventImpl(Window.java:2713)
	at java.awt.Component.dispatchEvent(Component.java:4686)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
	at java.awt.EventQueue.access$000(EventQueue.java:101)
	at java.awt.EventQueue$3.run(EventQueue.java:666)
	at java.awt.EventQueue$3.run(EventQueue.java:664)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
	at java.awt.EventQueue$4.run(EventQueue.java:680)
	at java.awt.EventQueue$4.run(EventQueue.java:678)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Here is my program:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
public class RectangleProgram extends JFrame
{
	private JLabel lengthLabel, widthLabel, areaLabel, perimeterLabel;
	private JTextField lengthText, widthText, areaText, perimeterText;
	private JButton calculateB, exitB;
 
	private CalculateButtonHandler cbHandler;
	private ExitButtonHandler ebHandler;
 
	public RectangleProgram()
	{
 
 
		setTitle("Area and perimeter of a Rectangle");
		setSize(500,300);
		setVisible(true);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		Container pane = getContentPane();
		pane.setLayout(new GridLayout(5, 2));
		JTextField lengthText = new JTextField(10);
		JTextField widthText = new JTextField(10);
		JTextField areaText = new JTextField(10);
		JTextField perimeterText = new JTextField(10);
		calculateB = new JButton("Calculate");
		exitB = new JButton("Exit");
 
		ebHandler = new ExitButtonHandler();
		cbHandler = new CalculateButtonHandler();
 
 
 
		JLabel lengthLabel = new JLabel("Enter the length:", SwingConstants.RIGHT);
		pane.add(lengthLabel);
		pane.add(lengthText);
		JLabel widthLabel = new JLabel("Enter the width:", SwingConstants.RIGHT);
		pane.add(widthLabel);
		pane.add(widthText);
		JLabel areaLabel = new JLabel("Area:", SwingConstants.RIGHT);
		pane.add(areaLabel);
		pane.add(areaText);
		JLabel perimeterLabel = new JLabel("Perimeter:", SwingConstants.RIGHT);
		pane.add(perimeterLabel);
		pane.add(perimeterText);
		pane.add(calculateB);
		pane.add(exitB);
 
		exitB.addActionListener(ebHandler);
		calculateB.addActionListener(cbHandler);
	}
 
	private class CalculateButtonHandler implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			double width, length, area, perimeter;
 
			length = Double.parseDouble(lengthText.getText()); ***********This is the line the compiler highlights***********
			width = Double.parseDouble(widthText.getText());
			area = length * width;
			perimeter = 2 * (width + length);
 
			areaText.setText("" + area);
			perimeterText.setText("" + perimeter);
 
		}
	}
 
	private class ExitButtonHandler implements  ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			System.exit(0);
		}
	}
 
	public static void main(String[] args)
	{
		RectangleProgram rec = new RectangleProgram();
 
	}
}

Thank you I feel so dumb.... I instantiated them first, then decided I wanted them private to that method. Dumb.... Thank you!!!!!!!!!!!!