java中增强for循环

public static void test(){
		int arr[] = {4,2,3};
		for(int i : arr){
			System.out.println(i);
		}
	}

下面是list

public static void test2(){
		List list = new ArrayList();
		list.add(1);
		list.add(3);
		list.add(4);
		
		for(Object obj : list){
			int i = (Integer)obj;
			System.out.println(i);
		}
	}

下面是map

public void test3(){
		Map map = new HashMap();
		map.put(1, "aa");
		map.put(2, "bb");
		map.put(3, "dd");
		
		for(Object obj : map.keySet()){
			Integer k = (Integer) obj;
			String v = (String)map.get(k);
			System.out.println(k+"::"+v);
		}
	}

此方法比较适合取数据，不适合修改数据