@Test	public void test2() {		List list = new ArrayList();		list.add(1);		list.add(2);		list.add(3);		list.add(4);				for(Object num : list){			int i = (Integer) num;			System.out.print(i+" ");		}	}		@Test	public void test3() {		//Map map = new HashMap();		Map map = new LinkedHashMap();				map.put("1", "aaa");		map.put("2", "bbb");		map.put("3", "ccc");		map.put("4", "ddd");				Set set = map.keySet();		Iterator it = set.iterator();		while(it.hasNext()){			String key = (String) it.next();			String value = http://www.mamicode.com/(String) map.get(key);"=" + value);		}	}}注意 只能取数据，不能改变数组货集合的数据