I read that Java provides default values to class properties, but not to local variables. Is that correct?
If so, what is the reason behind this? When you are doing something good, why not do it all the way?
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1Handy reference card for "Initial Values of Variables": java.sun.com/docs/books/jls/third_edition/html/…trashgod– trashgod2010-01-15 22:26:20 +00:00Commented Jan 15, 2010 at 22:26
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possible duplicate of Why are local variables not initialized in Java?Raedwald– Raedwald2014-03-11 13:08:00 +00:00Commented Mar 11, 2014 at 13:08
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Here's an updated link for trashgod's reference.jpaugh– jpaugh2015-12-24 17:40:50 +00:00Commented Dec 24, 2015 at 17:40
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2 Answers
Standard local variables are stored on the stack and aren't actually created until they are initialized. If a local variable isn't used, it doesn't go on the stack. Member variables, however, are allocated in the heap, and thusly have a default placeholder (null reference or default primitive).
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The non-technical reason behind may also be the following one:
If you declare a local variable, you do this in order to use it. And usage is connected with assigning a value. Therefore, accessing a declared, but not initialized, variable does not make that much sense - the programmer might simply have forgotten to initialize the variable.
Fields, however, might only be used until or after a specified point in the object's lifetime. Forcing the programmer to initialize them all would not be good.
