NullPointerException : Java Glossary

by Roedy Green ©1996-2008 Canadian Mind Products
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NullPointerException

If you try to execute a piece of code like this when s is null you will get a NullPointerException.

s.someMethod();

Java has no pointers; this properly should have been called a NullReferenceException, but it stuck from the early days where C terminology held an unwholesome influence.

It is one of many possible run time errors you can recover from. For hints on how to track down its cause, and the causes of many other errors see the essay on error messages .

To learn about exceptions in general and try/catch to recover from them, see exceptions.

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