List,set,map, inter-array conversion

List,set,map, inter-array conversion
1.list Turn Set
Set set = New HashSet (new ArrayList ());

2.set Goto List
List List = new ArrayList (new HashSet ());

3. Array to List
List stooges = arrays.aslist ("Larry", "Moe", "Curly");
Or
String[] arr = {"1", "2"};
List List = Arrays.aslist (arr);

4. Array to set
Int[] A = {1, 2, 3};
Set set = New HashSet (Arrays.aslist (a));

5.map of the relevant operation.
Map map = new HashMap ();
Map.put ("1", "a");
Map.put (' 2 ', ' B ');
Map.put (' 3 ', ' C ');
SYSTEM.OUT.PRINTLN (map);
All values are output
System.out.println (Map.keyset ());
All keys are output
System.out.println (Map.values ());
Convert the value of map to list
List List = new ArrayList (Map.values ());
SYSTEM.OUT.PRINTLN (list);
Convert the value of map to set
Set set = New HashSet (Map.values ());
SYSTEM.OUT.PRINTLN (set);

6.list Turn Array
List List = Arrays.aslist ("A", "B");
String[] arr = (string[]) List.toarray (new String[list.size ()]);
System.out.println (arrays.tostring (arr));

List,set,map, inter-array conversion