Java Learning Collection Framework (2) < good programmer training camp >

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1.Set interface

The set collection does not allow repeating elements, because set determines that two objects are the same not using the = = operator, but rather by the Equals method. That is, two objects cannot accept two objects by using the Equals method to return a true,set.

public class Setdemo{public static void Main (string[] args) {set<string> Set = new hashset<string> ();//Add one character String Object Set.add (New string ("ABCDE"));//Add a String object again, Set.add (new string ("ABCDE"));//The output below sees only one element of the collection System.out.println ( set);}}

2.HashSet

1) HashSet is not synchronous, multiple thread access is required to ensure synchronization through code

2) The collection element value can be null

Main methods: Principal- to-square method
Add (Object)
AddAll (Collection)
Remove (object)
RemoveAll (Collection)
Size ()
Iterator ()
ToArray ()
Clear ()
IsEmpty ()
Contain (object)
Containall (Collection)

Java Learning Collection Framework (2) < good programmer training camp >