need help with java empty field validation

Hello,

Can someone help me? Beginner with Java here. I'm trying to do a blank field validation. So far I got tons of errors. I tried so many different methods of validation code but no luck. I can't get the JOptionPane to show.

Here are the errors:
java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Num berFormatException.
java:48)
at java.lang.Integer.parseInt(Integer.java:489)
at java.lang.Integer.parseInt(Integer.java:518)
at PanelGroup.actionPerformed(PanelGroup.java:104)
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:17
86)
at javax.swing.AbstractButton$ForwardActionEvents.act ionPerformed(Abstra
ctButton.java:1839)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel
.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:258
)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonL
istener.java:245)
at java.awt.Component.processMouseEvent(Component.jav a:5100)
at java.awt.Component.processEvent(Component.java:489 7)
at java.awt.Container.processEvent(Container.java:156 9)
at java.awt.Component.dispatchEventImpl(Component.jav a:3615)
at java.awt.Container.dispatchEventImpl(Container.jav a:1627)
at java.awt.Component.dispatchEvent(Component.java:34 77)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:3483
)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:3198)

at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:3128)
at java.awt.Container.dispatchEventImpl(Container.jav a:1613)
at java.awt.Window.dispatchEventImpl(Window.java:1606 )
at java.awt.Component.dispatchEvent(Component.java:34 77)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 456)
at java.awt.EventDispatchThread.pumpOneEventForHierar chy(EventDispatchTh
read.java:201)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThre
ad.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:145)

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

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

Here's my code:
if(betField.getText().equals (""))
{
JOptionPane.showMessageDialog(null, "Show me the money!");
return;
//validation if the user didn't enter anything on the bet field
}


Been trying to fix this for 3 days...no luck.
Thanks.

Would need more information:

- from which class do you instantiate your betField?

- when do you validate (listeners, input verifiers etc.)?