A multidimensional map (made a class cause easy implementation)

MultiMap.java

public class MultiMap<J, K, L>{
  
  private HashMap<J, L> m1;
  private HashMap<K, L> m2;
  
  public MultiMap(){
    m1 = new HashMap<J, L>();
    m2 = new HashMap<K, L>();
  }

  public void add(J j, K k, L l){
    m1.add(j, l);
    m2.add(k, l);
  }  

  public L get(J j, K k){
    return m1.get(j) & m2.get(k); //This code was fabulous until I had to do this...
  }
  
  public static <J, K, L> MultiMap<J, K, L> of(J j, K k, L l){
    (new MultiMap<J, K, L>()).add(j, k, l);
  } 
}

MultiMap2.java

public class MultiMap<K, V>{
  
  private K[][];

  //Something with that?
  
  
}