Can ArrayList/HashMap be synchronized?

[amna vijay]

Was asked the following question in an interview:

Can we synchronize ArrayList or HashMap?
(I said we can - correct me if I am wrong)
If ArrayList and HashMap can be synchronized using synchronized keyword, then what is the use of having Vector and Hashtable?

[Manuel Leiria]

I'm not sure but I think it's just for backwards compatibility

[Paul Sturrock]

Have a look at Collections.synchronizedList() for an answer (though the method name probably gives you a huge clue ).

then what is the use of having Vector and Hashtable?

They are needed for legacy code. A better question is what is the point in using these for any new code?

[Rob Spoor]

I still wonder why these classes are not deprecated. And even if the classes are not, then why the "renamed" methods (e.g. addElement, elementAt) are not.

[Paul Clapham]

Originally posted by Rob Prime:
I still wonder why these classes are not deprecated. And even if the classes are not, then why the "renamed" methods (e.g. addElement, elementAt) are not.

There are several classes in Swing which use Vector internally (and in their public interfaces too). Perhaps Sun didn't want to change those classes, not even to use the methods from the List interface.

[Rob Spoor]

They wouldn't have to, they'd just have to turn off deprecation warnings.