HashMap
|
ConcurrentHashMap
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HashMap is not
thread safe.
|
ConcurrentHashMap
is Thread safe .
|
Relatively
performance high because thread are not required to wait to operate on
HashMap.
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Relatively performances is low because
some time Thread are required to wait to operate on ConcurrentHashMap.
|
While one thread
iterating HashMap the other Threads are not allowed to modify Map object
otherwise we will get Runtime exception saying
ConcurrentModificationException.
|
While one Thread
is iterating ConcurrentHashMap the other
Thread are allowed to modify Map object in safe manner and it won't throws
ConcurrentModificationException.
|
null is allowed
for both keys and values.
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null is not allowed for both keys and
values .otherwise we will get NullPointerException.
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introduced in 1.2
version.
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introduced in 1.5
version.
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Iterator of
HashMap is Fail-Fast and it throws ConcurrentModificationException.
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Iterator of ConcurrentHashMap is
Fail-Safe and it won't throws ConcurrentModificationException.
|
