Java Hashmap: How to get key from value?

Question

If I have the value \"foo\", and a HashMap ftw for which ftw.containsValue(\"foo\") returns true, how can I

Answer 1

I think this is best solution, original address: Java2s

    import java.util.HashMap;
    import java.util.Map;

        public class Main {

          public static void main(String[] argv) {
            Map map = new HashMap();
            map.put("1","one");
            map.put("2","two");
            map.put("3","three");
            map.put("4","four");

            System.out.println(getKeyFromValue(map,"three"));
          }


// hm is the map you are trying to get value from it
          public static Object getKeyFromValue(Map hm, Object value) {
            for (Object o : hm.keySet()) {
              if (hm.get(o).equals(value)) {
                return o;
              }
            }
            return null;
          }
        }

An easy usage: if you put all data in hasMap and you have item = "Automobile", so you are looking its key in hashMap. that is good solution.

getKeyFromValue(hashMap, item);
System.out.println("getKeyFromValue(hashMap, item): "+getKeyFromValue(hashMap, item));