Java tutorial
import java.util.Map; import java.util.WeakHashMap; public class Main { public static void main(String[] args) { WeakHashMap<String, String> weakHashMap = new WeakHashMap<String, String>(); weakHashMap.put("1", "first"); weakHashMap.put("2", "two"); weakHashMap.put("3", "from java2s.com"); // check existence of value "from java2s.com" System.out.println("Checking value 'three'"); System.out.println(weakHashMap.containsValue("from java2s.com")); } }