Map<String,Integer> map = new HashMap<>();
		map.put("AA",1);
		map.put("BB",2);
		map.put("CC",3);
		map.put("DD",4);
		map.put("EE",5);
		
		//迭代方式1:获取key的视图集合，然后根据map.get(key) 来获取value
		Set set=map.keySet();
		Iterator it=set.iterator();
		while(it.hasNext()){
			Object obj=it.next();
			System.out.println(obj+"--->"+map.get(obj));
		}
		
		//迭代方式2:获取entrySet，里面包含entry实体
		Set<Entry<String, Integer>> entries=map.entrySet();
		Iterator<Entry<String, Integer>> iterator=entries.iterator();
		while(iterator.hasNext()){
			Entry<String, Integer> entry=iterator.next();
			System.out.println(entry.getKey()+"-->>"+entry.getValue());
		}
		
		//迭代方式3:增强for循环
		for(Entry<String, Integer> entry: entries){
			System.out.println(entry.getKey()+"-->>"+entry.getValue());
		}