nullpointer exception

[nitin satish]

when i do SWING programs i am getting nullpointer exception.what should i do?

[faisal usmani]

it's really not possible to tell why there is such an error unless an until we have that part of the programme can u be a little more specific by sharing that part of the programme.

regards

[Henry Wong]

Or even better... give us the exact null pointer exception message. The NPE message is very good at targeting the class, method, file, and line number where the error occured.

Henry
[ April 30, 2006: Message edited by: Henry Wong ]

[Campbell Ritchie]

We have had this question before; the NullPointerException is one of the commonest. Look at this thread from the end of last year.
See whether it is of any help. There are several suggestions as to how to deal with such Exceptions. But what you ought not to be doing with most of at least these three Exceptions

NullPointerException

ArithmeticException

XYZIndexOutOfBoundsException

is to catch them, because they usually represent errors in the program somewhere.
No, you need to find out where they are occurring and prevent them.

NullPointerException means you have unintentionally forgotten to instantiate one of the objects, or (occasionally) have managed to destroy it without noticing.

...OutOfBoundsException means you haven't counted an array or String or something correctly and you are looking for a non-existent member.

ArithmeticException usually means you are trying to divide or "%" by zero.

If you ever have a method which deals with thoses situations and intentionally throws such an Exception, make sure you have a javadoc like this

/**
* This method works out xyz and abc
*@return result The result returned
*@throws NullPointerException if either xyz or abc is equal to null
*/    

CR