Java Collection Learning

First, the classification of the collection:

Second, the common collection:

1. Collections in Java COLLECTION:JDK

1. List

listlist<string>  list = new arraylist<>(), List.add ("a"), List.add ("B"), List.add ("C" ); SYSTEM.OUT.PRINTLN (list); [A, B, c]   

2. Map

mapmap<string,string>  map = new hashmap<>() map.put ("name", "by"); Map.put ("Age", "  ); SYSTEM.OUT.PRINTLN (map); {name=by, age=18}  

3. Set

// Set New Hashset<> (); Set.add ("a"); Set.add ("B"//  [A, b]

4. Iterator Traversal Collection

// iterator traversing the list collection Iterator Iterator = list.iterator ();  while (Iterator.hasnext ()) {    = (String) Iterator.next ();    System.out.println (parm);     if (Parm.equals ("a")) {        iterator.remove ();     // [B, C]

5. Traverse Map

/*** Traverse Map * * Get method: * First way: Use KeySet * need to get key and value separately, no object-oriented thought * set<k> KeySet () return all The set set of the Key object*/   Static voidTraversemap () {Map<integer, string> map =NewHashmap<>(); Map.put (1, "AAAA"); Map.put (2, "BBBB"); Map.put (3, "CCCC");       SYSTEM.OUT.PRINTLN (map); Set<Integer> KS =Map.keyset (); Iterator<Integer> it =Ks.iterator ();  while(It.hasnext ()) {Integer key=It.next (); String value=Map.get (key); System.out.println ("key=" + key + "value=" +value); }   }

2, Guava Collections (Google Open source tools)

1. List

// Create List list<string> list = Lists.newarraylist ("A", "B", "C"), List.add ("D"); // Invert list // [D, C, B, a] // converts a list collection to a string of a specific rule String Listresult = Joiner.on ("-"//  a-b-c-d

2. Map

//Define Mapmap<string,string > Map =Maps.newhashmap (); Map.put ("Name", "by"); Map.put ("Age", "23"); SYSTEM.OUT.PRINTLN (map); //{name=by, age=23}//converts a map collection to a specific rule stringString Mapresult = Joiner.on (","). Withkeyvalueseparator ("=")). Join (map); System.out.println (Mapresult); //name=by,age=23//define the form of a list in Map (map<string,list<integer>>)Multimap<string,integer> maps =arraylistmultimap.create (); Maps.put ("Map", 1); Maps.put ("Map", 2); SYSTEM.OUT.PRINTLN (maps); //{map=[1, 2]}

3. Set

// Define set set<string> set = sets.newhashset (); Set.add ("value");

3, Trove

1. Constructs a collection of basic types

// directly constructs a collection of type int New tintarraylist (); Intlist.add (1); Intlist.add (2); Intlist.add (3); Intlist.reverse (); System.out.println (intlist);

Java Collection Learning