1 @Test 2     public void testFor3(){ 3         String[] str = new String[]{"AA","BB","DD"}; 4         for(String s : str){ 5             s =  "MM";//此处的s是新定义的局部变量，其值的修改不会对str本身造成影响。 6             System.out.println(s); 7         }         8          9         for(int i = 0;i < str.length;i++){10             System.out.println(str[i]);11         }12     }13     @Test14     public void testFor2(){15         String[] str = new String[]{"AA","BB","DD"};16         for(int i = 0;i < str.length;i++){17             str[i] = i + "";18         }19         20         for(int i = 0;i < str.length;i++){21             System.out.println(str[i]);22         }23     }24     25     //***********************************************26     //使用增强for循环实现数组的遍历27     @Test28     public void testFor1(){29         String[] str = new String[]{"AA","BB","DD"};30         for(String s:str){31             System.out.println(s);32         }33     }34     35     //使用增强for循环实现集合的遍历36     @Test37     public void testFor(){38         Collection coll = new ArrayList();39         coll.add(123);40         coll.add(new String("AA"));41         coll.add(new Date());42         coll.add("BB");43         44         for(Object i:coll){45             System.out.println(i);46         }47     }48     49     //错误的写法50     @Test51     public void test2(){52         Collection coll = new ArrayList();53         coll.add(123);54         coll.add(new String("AA"));55         coll.add(new Date());56         coll.add("BB");57         coll.add(new Person("MM", 23));58         59         Iterator i = coll.iterator();60         61         while((i.next())!= null){62             //java.util.NoSuchElementException63             System.out.println(i.next());64         }65     }66     //正确的写法：使用迭代器Iterator实现集合的遍历67     @Test68     public void test1(){69         Collection coll = new ArrayList();70         coll.add(123);71         coll.add(new String("AA"));72         coll.add(new Date());73         coll.add("BB");74         75         Iterator i = coll.iterator();76         while(i.hasNext()){77             System.out.println(i.next());78         }79     }