Java遍历Map的5种方式实例

Map<Integer,Integer> map= new HashMap<>();
for(int i=0;i<10000;i++){
    map.put(i,i+1);
}

//keySet获取key
@Test
public  void testKeySet(){
    for (Integer key: map.keySet()){
        System.out.println(key);
    }
}
 
//values获取value
@Test
public  void testValues(){
   for (Integer value: map.values()){
       System.out.println(value);
   }
}

//keySet get(key)获取key 和value
    @Test
    public void testKeySetAndGetKey(){
        for(Integer key: map.keySet()){
            System.out.println(key+":"+map.get(key));
        }
    }

@Test
public void testEntry(){
    for (Map.Entry<Integer,Integer> entry: map.entrySet()){
        System.out.println(entry.getKey()+":"+entry.getValue());
    }
}

//Iterator entrySet获取key和value
    public void testIterator(){
        Iterator<Map.Entry<Integer,Integer>> it = map.entrySet().iterator();
        while (it.hasNext()){
            Map.Entry<Integer,Integer> entry = it.next();
            System.out.println(entry.getKey()+":"+ entry.getValue());
            it.remove();//删除元素
        }
    }

public void testLambda(){
        map.forEach((key,value)->{
            System.out.println(key+":"+value);
        });
    }