import java.util.IdentityHashMap;
import java.util.Map;

public class AssociatingAValue {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Map objMap = new IdentityHashMap();

    // Add the object and value pair to the map
    Object o1 = new Integer(123);
    Object o2 = new Integer(123);
    objMap.put(o1, "first");
    objMap.put(o2, "second");

    // Retrieve the value associated with the objects
    Object v1 = objMap.get(o1); // first
    Object v2 = objMap.get(o2); // second
    System.out.println(objMap);
}

}
Console：
{123=first, 123=second}