import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

public class M{
public static void main(String[] args) {

        HashMap<String, List<String>> resultHashMap = new HashMap<String, List<String>>();

        Set<String> newKeyList = resultHashMap.keySet();


        for (Iterator<String> iterator = originalHashMap.keySet().iterator(); iterator.hasNext();) {
            String hashKey = (String) iterator.next();

            if (!newKeyList.contains(originalHashMap.get(hashKey))) {
                List<String> loArrayList = new ArrayList<String>();
                loArrayList.add(hashKey);
                resultHashMap.put(originalHashMap.get(hashKey), loArrayList);
            } else {
                List<String> loArrayList = resultHashMap.get(originalHashMap
                        .get(hashKey));
                loArrayList.add(hashKey);
                resultHashMap.put(originalHashMap.get(hashKey), loArrayList);
            }
        }

        System.out.println("Original HashMap : " + originalHashMap);
        System.out.println("Result HashMap : " + resultHashMap);
    }
}

你也可以这样做: 第一个:put map (key, value) 第二:更新键需要删除表达式 第三:和oldValue一起放一个新键

听起来最好的方法是使用map.entrySet()来遍历条目，因为map.containsValue()可能会这样做。

让我们看看我的例子

Map<String, String> mapPeopleAndCountry = new HashMap<>();
mapPeopleAndCountry.put("Matis", "Lithuania");
mapPeopleAndCountry.put("Carlos", "Honduras");
mapPeopleAndCountry.put("Teboho", "Lesotho");
mapPeopleAndCountry.put("Marielos", "Honduras");


List<String> peopleInHonduras = mapPeopleAndCountry.keySet()
    .stream()
    .filter(r -> mapPeopleAndCountry.get(r)
                .equals("Honduras"))
    .stream(Collectors.toList());

// will return ["Carlos", "Marielos"]

注:未经测试，可能含有错别字

我认为你的选择是

Use a map implementation built for this, like the BiMap from google collections. Note that the google collections BiMap requires uniqueless of values, as well as keys, but it provides high performance in both directions performance Manually maintain two maps - one for key -> value, and another map for value -> key Iterate through the entrySet() and to find the keys which match the value. This is the slowest method, since it requires iterating through the entire collection, while the other two methods don't require that.

你可以使用下面的:

public class HashmapKeyExist {
    public static void main(String[] args) {
        HashMap<String, String> hmap = new HashMap<String, String>();
        hmap.put("1", "Bala");
        hmap.put("2", "Test");

        Boolean cantain = hmap.containsValue("Bala");
        if(hmap.containsKey("2") && hmap.containsValue("Test"))
        {
            System.out.println("Yes");
        }
        if(cantain == true)
        {
            System.out.println("Yes"); 
        }

        Set setkeys = hmap.keySet();
        Iterator it = setkeys.iterator();

        while(it.hasNext())
        {
            String key = (String) it.next();
            if (hmap.get(key).equals("Bala"))
            {
                System.out.println(key);
            }
        }
    }
}