How are emptySet(), singleton & unmodifiable methods in Java Collections useful?

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Surya Prabha

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"emptySet()" is used to return empty and unmodifiable set. Instead of deals with returning null it will return empty. we can avoid nullpointerexception. Also returned empty set is unmodifiable we will get UnsupportedOperationException if we try to modify. All unmodifiable methods like Collections.unmodifiableSet,Collections.unmodifiableList,Collections.unmodifiableMap...
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"emptySet()" is used to return empty and unmodifiable set. Instead of deals with returning null it will return empty. we can avoid nullpointerexception. Also returned empty set is unmodifiable we will get UnsupportedOperationException if we try to modify. All unmodifiable methods like Collections.unmodifiableSet,Collections.unmodifiableList,Collections.unmodifiableMap will return unmodifiable list,set,map and whenever we will get the scenario that the client or any third party vendor should not allow to modify list or set or map once it get generated we can go for unmodifiable methods.It allows us to share a list, set or map with another objects without giving them the possibility to modify them, while we can manipulate them as required. "Collections.singleton" this method is to remove an element from Collections like List and Set at once. Let as take Example, I have list {1,2,5,2,4,9,2} if i try to remove '2' without using singleton i will get result as, Remove 2 without using singleton:{1,5,2,4,9,2} Remove 2 with using singleton:{1,5,4,9} it will remove all '2' at once. read less
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