Set of explanations

Set Set

Common methods:

1, int size (): Returns the number of elements in the set

2. Boolean isEmpty (): Returns True if no element is included

3, contains (Object O): Returns True if the specified element is included

4. Boolean Add (Object O): If the specified element does not exist, then add to the set

5. Void Clear (): Remove all elements from set

6. Boolean RemoveAll (Collection C): If the set contains the specified collection, remove all elements from the set that make the collection

Implementation class:

HashSet: There is no relationship between the order in which elements are stored and the order in which they are added

Linkedhashset: Preserving the order in which elements are added

TreeSet: Sort the elements in a set

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List Collection

Common methods:

1. public void Add (E Element)

2. public void Add (int index,eelement)

3. public void AddAll (E element)

4. public void AddAll (Intindex,collection c)

Implementation class:

ArrayList: Asynchronous processing with high performance and non-thread-safe

Vector: Synchronous processing, low performance, thread safety

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Set of explanations