HashMap usage of Java

Source: Internet
Author: User
Tags random seed


1  PackageTest_demo;2 3 ImportJava.util.HashMap;4 ImportJava.util.Iterator;5 ImportJava.util.Map;6 ImportJava.util.Random;7 8 /*9 * @desc hashmap test programTen  */ One  A  Public classHashmapdemo { -     Private Static voidTesthashmapapis () { -         //Initialize random seed theRandom r =NewRandom (); -         //New HashMap -HashMap map =NewHashMap (); -         //Add Action +Map.put ("One", R.nextint (10)); -Map.put ("I", R.nextint (10)); +Map.put ("Three", R.nextint (10)); A         //print out a map atSYSTEM.OUT.PRINTLN ("Map:" +map); -         //Traverse Key-value via iterator -Iterator iter =Map.entryset (). iterator (); -          while(Iter.hasnext ()) { -Map.entry Entry =(Map.entry) Iter.next (); -System.out.println ("Next:" + entry.getkey () + ":" +Entry.getvalue ()); in         } -         //hashmap number of key-value pairs toSYSTEM.OUT.PRINTLN ("Size:" +map.size ()); +         //ContainsKey (Object key): Contains key -System.out.println ("contains key:" + Map.containskey (")); theSystem.out.println ("contains key five:" + Map.containskey ("five")); *         //Containsvalue (Object value): Whether the value is inclusive $System.out.println ("contains value 0:" + map.containsvalue (NewInteger (0)));Panax Notoginseng         //Remove (Object key): Key value pair corresponding to key key -Map.Remove ("three"); theSystem.out.println ("Delete three"); +SYSTEM.OUT.PRINTLN ("Map:" +map); A         //Clear (): Empty HashMap the map.clear (); +System.out.println ("Empty HashMap"); -         //isEmpty (): HashMap is empty $System.out.println (Map.isempty ()? "Map is empty": "Map is not empty")); $     } -  -      Public Static voidMain (string[] args) { the Testhashmapapis (); -     }Wuyi}

Execution Result:

Map:{one=1, Two=9, Three=2}next:  one:1next:  two:9next: Three:2size:3contains  key Two:truecontains key F Ive:falsecontains value 0:false Delete threemap:{one=1, two=9} empty Hashmapmap is empty


HashMap usage of Java

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