Java Collection Transformations (arrays, List, Set, map conversions)

Reprinted from: http://blog.csdn.net/top_code/article/details/10552827

Code:

 Packagecom.example.test;Importjava.util.ArrayList;Importjava.util.Arrays;ImportJava.util.HashMap;ImportJava.util.HashSet;Importjava.util.List;ImportJava.util.Map;ImportJava.util.Set; Public classConvertortest {/**     * @paramargs*/     Public Static voidMain (string[] args) {Testlist2array ();        Testarray2list ();        Testset2list ();        Testlist2set ();        Testset2array ();        Testarray2set ();        Testmap2set ();    Testmap2list (); }    Private Static voidtestmap2list () {Map<string, string> map =NewHashmap<string, string>(); Map.put ("A", "ABC"); Map.put ("K", "KK"); Map.put ("L", "LV"); //Convert map Key to listList<string> mapkeylist =NewArraylist<string>(Map.keyset ()); System.out.println ("Mapkeylist:" +mapkeylist); //Convert map Key to listList<string> mapvalueslist =NewArraylist<string>(Map.values ()); System.out.println ("Mapvalueslist:" +mapvalueslist); }    Private Static voidTestmap2set () {Map<string, string> map =NewHashmap<string, string>(); Map.put ("A", "ABC"); Map.put ("K", "KK"); Map.put ("L", "LV"); //Converts the map's key to setSet<string> Mapkeyset =Map.keyset (); System.out.println ("Mapkeyset:" +mapkeyset); //Convert the value of map to setSet<string> Mapvaluesset =NewHashset<string>(Map.values ()); System.out.println ("Mapvaluesset:" +mapvaluesset); }    Private Static voidTestarray2set () {string[] arr= {"AA", "BB", "DD", "CC", "BB"}; //Array-->setSet<string> set =NewHashset<string>(Arrays.aslist (arr));      SYSTEM.OUT.PRINTLN (set); }    Private Static voidTestset2array () {Set<String> set =NewHashset<string>(); Set.add ("AA"); Set.add ("BB"); Set.add ("CC"); String[] Arr=Newstring[set.size ()]; //set--> ArraySet.toarray (arr);      System.out.println (arrays.tostring (arr)); }    Private Static voidTestlist2set () {List<String> list =NewArraylist<string>(); List.add ("ABC"); List.add ("EFG"); List.add ("LMN"); List.add ("LMN"); //List-->setSet<string> Listset =NewHashset<string>(list);    System.out.println (Listset); }    Private Static voidtestset2list () {Set<String> set =NewHashset<string>(); Set.add ("AA"); Set.add ("BB"); Set.add ("CC"); //Set --ListList<string> setlist =NewArraylist<string>(set);      System.out.println (setlist); }    Private Static voidTestlist2array () {//list--> Arraylist<string> list =NewArraylist<string>(); List.add ("AA"); List.add ("BB"); List.add ("CC"); Object[] Objects= List.toarray ();//returns an Object arraySystem.out.println ("Objects:" +arrays.tostring (objects)); String[] Arr=Newstring[list.size ()]; List.toarray (arr);//put the converted array into an already created objectSystem.out.println ("STRINGS1:" +arrays.tostring (arr)); }        Private Static voidtestarray2list () {//Array-->liststring[] ss = {"JJ", "KK"}; List<String> List1 =arrays.aslist (ss); List<String> List2 = arrays.aslist ("AAA", "BBB");          System.out.println (List1);      System.out.println (LIST2); }}

Complete.

Java Collection Transformations (arrays, List, Set, map conversions)