Map Query and Modification methods

How to 1:map queries

 PackageCom.cn.util;Importjava.util.ArrayList;ImportJava.util.HashMap;ImportJava.util.Iterator;Importjava.util.List;ImportJava.util.Map;ImportJava.util.Set;//a method of looping through a map Public classUtil { Public Static voidMain (string[] args) {Map<string, integer> tempmap =NewHashmap<string, integer>(); Tempmap.put ("A", 1); Tempmap.put ("B", 2); Tempmap.put ("C", 3); //in JDK1.4//Traversal method One HashMap entryset () traversalSystem.out.println ("Method One")); Iterator it=Tempmap.entryset (). iterator ();  while(It.hasnext ()) {Map.entry Entry=(Map.entry) it.next (); Object Key=Entry.getkey (); Object value=Entry.getvalue (); System.out.println ("key=" + key + "value=" +value); } System.out.println (""); //JDK1.5, apply new features For-each loop//Traversal Method TwoSystem.out.println ("Method Two");  for(Map.entry<string, integer>Entry:tempMap.entrySet ()) {String key=Entry.getkey (). toString (); String value=Entry.getvalue (). toString (); System.out.println ("key=" + key + "value=" +value); } System.out.println (""); //Traversal Method Three HashMap KeySet () traversalSystem.out.println ("Method three");  for(Iterator i =Tempmap.keyset (). iterator (); I.hasnext ();) {Object obj=I.next (); System.out.println (obj);//Loop Output KeySystem.out.println ("key=" + obj + "value=" +tempmap.get (obj)); }         for(Iterator i =tempmap.values (). iterator (); I.hasnext ();) {Object obj=I.next (); System.out.println (obj);//Loop Output Value} System.out.println (""); //Traversal method four TreeMap KeySet () traversalSystem.out.println ("Method Four");  for(Object o:tempmap.keyset ()) {System.out.println ("key=" + O + "value=" +tempmap.get (o)); } System.out.println ("11111"); //how Java traverses map <string, arraylist> map = new HashMap <string,//arraylist> ();System.out. println ("Java Traversal map <string, arraylist> map = new HashMap <string, arraylist> ();"); Map<string, arraylist> map =NewHashmap<string, arraylist>(); Set<String> keys =Map.keyset (); Iterator<String> iterator =Keys.iterator ();  while(Iterator.hasnext ()) {String key=Iterator.next (); ArrayList ArrayList=Map.get (key);  for(Object o:arraylist) {System.out.println (o+ "Traversal Process"); }} System.out.println ("2222"); Map<string, list> maplist =NewHashmap<string, list>();  for(Map.entry entry:mapList.entrySet ()) {String key=Entry.getkey (). toString (); List<String> values =(List) entry.getvalue ();  for(String value:values) {System.out.println (key+ "-+" +value); }        }    }}

Query methods for 2:map

 PackageCom.cn.util;ImportJava.util.HashMap;ImportJava.util.Map;ImportJava.util.Set; Public classMaptest { Public Static voidTest1 () {Map<string, integer> m =NewHashmap<string, integer>(); M.put ("1", 20); M.put ("2", 30); Set<String> s = m.keyset ();//get the Key collection         for(String str:s) {m.put (str, (int) (M.get (str) * 1.3));//value in key} System.out.println (M.get ("1" + "+" + m.get ("2"))); }     Public Static voidMain (string[] args) {Test1 (); }}

Map Query and Modification methods