Java Instance-Collection traversal

Traversal of the list and set type collection

1 Importjava.util.ArrayList;2 ImportJava.util.HashSet;3 ImportJava.util.Iterator;4 Importjava.util.List;5 ImportJava.util.Set;6  7  Public classMain {8  9     Public Static voidMain (string[] args) {Ten       //traversal of the list collection One listtest (); A       //traversal of Set set - settest (); -    } the   -    Private Static voidsettest () { -Set<string> set =NewHashset<string>(); -Set.add ("JAVA"); +Set.add ("C"); -Set.add ("C + +"); +       //Duplicate data addition failed ASet.add ("JAVA"); atSet.add ("JAVASCRIPT"); -   -       //To traverse a set collection using iterator -Iterator<string> it =set.iterator (); -        while(It.hasnext ()) { -String value =It.next (); in System.out.println (value); -       } to        +       //traversing a set collection using an enhanced for loop -        for(String s:set) { the System.out.println (s); *       } $    }Panax Notoginseng   -    //traversing the list collection the    Private Static voidlisttest () { +list<string> list =NewArraylist<string>(); AList.add ("W"); theList.add ("M"); +List.add ("L"); -List.add ("D"); $List.add ("www.pekst.com"); $   -       //using iterator traversal -Iterator<string> it =list.iterator (); the        while(It.hasnext ()) { -String value =It.next ();Wuyi System.out.println (value); the       } -   Wu       //traversing with a traditional for loop -        for(inti = 0, size = list.size (); i < size; i++) { AboutString value =List.get (i); $ System.out.println (value); -       } -   -       //traverse with enhanced for loop A        for(String value:list) { + System.out.println (value); the       } -    } $}

About traversal of a collection of map types

In the following example we use HashMap's KeySet () and EntrySet () methods to iterate through the collection:

1 ImportJava.util.Map;2 ImportJava.util.HashMap;3 ImportJava.util.HashSet;4 ImportJava.util.Iterator;5 Importjava.util.List;6 ImportJava.util.Set;7 ImportJava.util.Map.Entry;8 9 //Enhanced for LoopTen  Public classMain { One  A     Public Static voidMain (string[] args) { -       //creates a HashMap object and joins some key-value pairs.  -Map<string, string> maps =NewHashmap<string, string>(); theMaps.put ("1", "PHP"); -Maps.put ("2", "Java"); -Maps.put ("3", "C"); -Maps.put ("4", "C + +"); +Maps.put ("5", "HTML"); -        +       //traditional method of traversing the map set 1; KeySet () A       //traditionalMethod1 (maps); at       //traditional method of traversing the map set 2; EntrySet () -       //TRADITIONALMETHOD2 (maps); -       //use the enhanced for loop to traverse the Map collection Method 1; KeySet () -       //strongForMethod1 (maps); -       //use the enhanced for loop to traverse the Map collection Method 2; EntrySet () - STRONGFORMETHOD2 (maps); in    } -  to    Private Static voidSTRONGFORMETHOD2 (map<string, string>maps) { +Set<entry<string, string>> set =Maps.entryset (); -        for(Entry<string, string>Entry:set) { theString key =Entry.getkey (); *String value =Entry.getvalue (); $SYSTEM.OUT.PRINTLN (key + ":" +value);Panax Notoginseng       } -    } the  +    Private Static voidStrongForMethod1 (map<string, string>maps) { ASet<string> set =Maps.keyset (); the        for(String s:set) { +String key =s; -String value =Maps.get (s); $SYSTEM.OUT.PRINTLN (key + ":" +value); $       } -    } -  the    //Use the EntrySet () method to get each key-value pair in the Maps collection, -    Private Static voidTRADITIONALMETHOD2 (map<string, string>maps) {Wuyiset<map.entry<string, string>> sets =Maps.entryset (); the       //gets the iterator that iterates out the corresponding value.  -Iterator<entry<string, string>> it =sets.iterator (); Wu        while(It.hasnext ()) { -map.entry<string, string> Entry = (entry<string, string>) It.next (); AboutString key =Entry.getkey (); $String value =Entry.getvalue (); -SYSTEM.OUT.PRINTLN (key + ":" +value); -       } -    } A  +    //Use the Keyset () method to get all the keys in the Maps collection and traverse the keys to get the corresponding values.  the    Private Static voidTraditionalMethod1 (map<string, string>maps) { -Set<string> sets =Maps.keyset (); $       //gets the iterator to traverse the corresponding value theIterator<string> it =sets.iterator (); the        while(It.hasnext ()) { theString key =It.next (); theString value =Maps.get (key); -SYSTEM.OUT.PRINTLN (key + ":" +value); in       } the    } the}

Java Instance-Collection traversal