Java hash table problem with object reference

I have a hash table like,

HashTable ht = { (1, 1), (2, 1), (3, 1) }

      

        
        
        
      

    

Now I am implementing this as Integer foo = Integer (1) and declaring the hash table as,

HashTable ht = { (foo, foo), (2, foo), (3, foo) }

      

        
        
        
      

    

Now, as I understood from this , this will reduce the heap space used by the JVM. It is right? Another thing is that in C I usually use a structure like,

HashTable ht = { (1, mem), (2, mem), (3, mem) } 
{ where mem is memory location (say 10) of 1 }

      

        
        
        
      

    

And then use location to access the value. Now if the mem value is less than Int (say in bytes) I can save space. However, I don't understand how to implement this in Java. Or is there some other way to reduce the space of the hash table? (means shorthand for multiple storage of the same object in Java).