I have a program that takes in data from the user, calculates the data and is
supposed to display the results in a window. The program compiles and the
user is able to type in data, but when you click the calculate button, the
errors that come up are the following:

java.lang.NumberFormatException: For input string: "Enter Length"
       at java.lang.NumberFormatException.forInputString
(NumberFormatException.
java:48)
       at java.lang.Integer.parseInt(Integer.java:468)
       at java.lang.Integer.parseInt(Integer.java:518)
       at Program81$ButtonHandler.actionPerformed(Program81.java:38)
       at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:
17
86)
       at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed
(Abstra
ctButton.java:1839)
       at javax.swing.DefaultButtonModel.fireActionPerformed
(DefaultButtonModel
.java:420)
       at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:
258
)
       at javax.swing.plaf.basic.BasicButtonListener.mouseReleased
(BasicButtonL
istener.java:245)
       at java.awt.Component.processMouseEvent(Component.java:5100)
       at java.awt.Component.processEvent(Component.java:4897)
       at java.awt.Container.processEvent(Container.java:1569)
       at java.awt.Component.dispatchEventImpl(Component.java:3615)
       at java.awt.Container.dispatchEventImpl(Container.java:1627)
       at java.awt.Component.dispatchEvent(Component.java:3477)
       at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:
3483
)
       at java.awt.LightweightDispatcher.processMouseEvent(Container.java:
3198)

       at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
       at java.awt.Container.dispatchEventImpl(Container.java:1613)
       at java.awt.Window.dispatchEventImpl(Window.java:1606)
       at java.awt.Component.dispatchEvent(Component.java:3477)
       at java.awt.EventQueue.dispatchEvent(EventQueue.java:480)
       at java.awt.EventDispatchThread.pumpOneEventForHierarchy
(EventDispatchTh
read.java:201)
       at java.awt.EventDispatchThread.pumpEventsForHierarchy
(EventDispatchThre
ad.java:151)
       at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:
145)

       at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:
137)

       at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

The code that the error is referencing is:

    private class ButtonHandler implements ActionListener {

            public void actionPerformed(ActionEvent event)  {

                rectangle r = new rectangle();

                r.setWidth(Integer.parseInt(dataWidth.getText()));

                r.setLength(Integer.parseInt(enterLength.getText()));

                calculateArea.setText("The area of your rectangle is " + r.calcArea());

                calculatePerim.setText("The perimeter of your rectangle is " + r.
calcPerimeter());
            }
    }//end of action handler

What is the cause of this and how do I remedy it? I have no experience with
IO. thank you so much for your help.