Null pointer when calling a method in another class

Question

I have an input panel and want to call a method in another class when the button is pressed but am getting a null pointer exception. Was hoping someone might be able to tell me what I'm doing wrong?

Here is the code causing it:

public void actionPerformed(ActionEvent ae)
    {
        if (ae.getSource() == resultsButton)
        {
            jbTour.processAdditionalResult();
        }

    }


public void processAdditionalResult()
    {
        System.out.println("button pressed");
    }

Add the exception stack traces, then we can find the error easily.. — Abimaran Kugathasan
– Abimaran Kugathasan, Commented Jan 7, 2012 at 18:50

Mike Nakis · Accepted Answer · 2012-01-07 18:51:58Z

3

You need to initialize jbTour: jbTour = new JBTourObject() (or whatever) so that it is not null before the actionPerformed method gets invoked.

answered Jan 7, 2012 at 18:51

Mike Nakis

63k11 gold badges128 silver badges173 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

duffymo · Accepted Answer · 2012-01-07 18:52:13Z

1

I think I can tell even without the stack trace: jbTour is null. You've declared a name of that reference type in the class that implements the ActionListener interface, but you never initialized it to point a new reference.

answered Jan 7, 2012 at 18:52

duffymo

310k46 gold badges376 silver badges571 bronze badges

Comments

Peter Lawrey · Accepted Answer · 2012-01-07 18:52:52Z

1

If this throws a NullPointerException

jbTour.processAdditionalResult();

that means jbTour has not been set or is null.

answered Jan 7, 2012 at 18:52

Peter Lawrey

535k83 gold badges770 silver badges1.2k bronze badges

Collectives™ on Stack Overflow

Null pointer when calling a method in another class

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related