public class MyKey implements Comparable<MyKey>
{
private Integer i;
private String s;
public MyKey(Integer i,String s)
{
this.i=i;
this.s=s;
}

public Integer getI() { return i;}
public String getS() { return s;}

@Override
public int hashcode()
{
return i.hashcode()+31*s.hashcode();
}

@Override
public boolean equals(Object o)
{
if(o==this) return true;
if(o==null || !(o instanceof MyKey)) return false;
MyKey cp= MyKey.class.cast(o);
return i.equals(cp.i) && s.equals(cp.s);
    }

   public int compareTo(MyKey cp)
     {
     if(cp==this) return 0;
     int i= i.compareTo(cp.i);
     if(i!=0) return i;
     return s.compareTo(cp.s);
     }


 @Override
    public String toString()
       {
       return "("+i+";"+s+")";
       }

    }

public Map<MyKey,String> map= new HashMap<MyKey,String>();
map.put(new MyKey(1,"Hello"),"world");

map.put(Arrays.asList(keyClass, keyString), value)

public class Key {

    public MyClass key_class;
    public String key_string;

    public Key(){
        key_class = new MyClass();
        key_string = "";
    }

}

public class KeyClass {

    private String element1;
    private String element2;

    //boilerplate code here

    public boolean equals(Object obj) {
        if (obj instanceof KeyClass) {
            return element1.equals(((KeyClass)obj).element1) &&
                element2.equals(((KeyClass)obj).element2);
        }
        return false;
    }

    public int hashcode() {
        return (element1 + element2).hashcode();
    }
}

Map<Key1, value>

Map<Key2, value>

Map<Key1, Map<Key2, value>>

class KeyHolder {
    public final String key;
    public final Object storeMe;

    public KeyHolder(String key, Object storeMe) {
        this.key=key;
        this.storeMe=storeMe;
    }

    public equals(Object o) {
        return (o instanceof KeyHolder && ((KeyHolder)o).key.equals(key));
    }

    public hashcode() {
        return key.hashCode();
    }
}