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>(); // check map contents System.out.println("Checking the map entries"); System.out.println("Map is empty: " + weakHashMap.isEmpty()); System.out.println("Putting values into the Map"); weakHashMap.put("1", "first"); weakHashMap.put("2", "two"); weakHashMap.put("3", "from java2s.com"); // checking Map System.out.println("Map is empty: " + weakHashMap.isEmpty()); } }