hashmap 遍历

https://blog.youkuaiyun.com/fuzhongbin/article/details/50521877

public class Main{
    public static void main(String[] args) {
        Map map=new HashMap();
        map.put("王", 1);
        map.put("杨", 2);
        map.put("赵", 3);

        //遍历方式1:遍历key和value
        Iterator it=map.entrySet().iterator();
        while(it.hasNext()){
            Entry entry=(Entry)it.next();
            Object key=entry.getKey();
            Object value=entry.getValue();
            System.out.println(key+":"+value);
        }
        System.out.println();

        //遍历方式2:遍历整个Hashmap 
        Collection objs=map.entrySet();
        for(Iterator iterator=objs.iterator();iterator.hasNext();){
            Object obj=iterator.next();
            System.out.println(obj);
        }
        System.out.println();

        //遍历方式3：遍历Hashmap的key，根据key获得value
        Collection keys=map.keySet();
        for(Iterator iterator=keys.iterator();iterator.hasNext();){
            Object key=iterator.next();
            Object value=map.get(key);
            System.out.println(key+":"+value);
        }
        System.out.println();

        //遍历方式4：遍历Hashmap的value
        Collection values=map.values();
        for(Iterator iterator=values.iterator();iterator.hasNext();){
            Object value=iterator.next();
            System.out.println(value);
        }
}

output:

赵:3
王:1
杨:2

赵=3
王=1
杨=2

赵:3
王:1
杨:2

3
1
2