Java 集合的迭代操作 Iterator

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幾種實現 列出如下  

 1 import java.util.*; 2  3 /** 4  * Created by wojia on 2017/6/13. 5  */ 6 public class IteratorDemo { 7         public static void main(String args[]){ 8             List list = new ArrayList(); 9             list.add("A");10             list.add("B");11             list.add("C");12             list.add("D");13             System.out.println(list);14             /*list 集合的迭代操作*/15             //1. for loop16             for(int index = 0 ; index < list.size() ; index++){ //it‘s method which declared as size() , not a variable  size.17                 Object temp = list.get(index);18                 System.out.print(temp);19 20             }21             System.out.println();22 23             //2. for - each loop24             for(Object ele : list){25                 System.out.print(ele);26             }27             System.out.println();28 29             //3. Use iterator30             /**list.iterator will return an iterator Object*/31             Iterator iterator = list.iterator();32             while(iterator.hasNext()){33                 System.out.print(iterator.next());//next()is a method34             }35 36             //4. Use for loop37             /**38              * this method is the best ,better than while loop , because of the gc 39              * */40             for(Iterator it = list.iterator();iterator.hasNext();){41                 System.out.print(it.next());42             }43 44         }45 46     }

  

Java 集合的迭代操作 Iterator