Java tutorial
import java.util.Collection; 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>(); System.out.println("Putting values into the Map"); weakHashMap.put("1", "first"); weakHashMap.put("2", "two"); weakHashMap.put("3", "from java2s.com"); // checking the size of the Map System.out.println("Map values: " + weakHashMap); Collection col = weakHashMap.values(); System.out.println("Collection values: " + col); } }