How do I retrieve a value from two objects in Java?

Question

I want to do something like the following:

MyObject obj1 = new MyObject();
MyObject obj2 = new MyObject();
MyObject obj3 = new MyObject();
MyObject obj4 = new MyObject();

values[obj1][obj2] = 1;
values[obj2][obj4] = 2;
values[obj1][obj4] = 3;

int someValue = values[obj1][obj2];
int someOtherValue = values[obj2][obj4];
int anotherValue = values[obj1][obj4];

How do I create these getter and setters with two objects as the key in Java?

Answer 1

The syntax in your question looks more like C#, and is not valid in Java, where array indices must be integers.

You can create a Pair<F,S> class that contains references to two objects.

Then you can create a HashMap<Pair<MyObject,MyObject>,Integer> , so a Pair of MyObject instances would serve as the key.

Map<Pair<MyObject,MyObject>,Integer> values = new HashMap<>();

Then you'll assign values with:

values.put(new Pair<>(obj1,ob2), 1);

and get the value with:

Integer someValue = values.get(new Pair<>(obj1,ob2));

You'll have to properly override equals and hashCode is both the Pair class and the MyObject class.

Answer 2

You can Use another Class to return the Two Object.. may be you can work around this

    final class MyResultObject {
            private final MyObject firstObject;
            private final MyObject secondObject;
        private final int key;
            public MyResult(MyObject firstObject, MyObject secondObject ,int key) {
                this.firstObject = firstObject;
                this.secondObject = secondObject;
                this.key=key;
            }


    public int getKey() {
                return key;
            }
    Public int getKeyValue(MyObject Object1, MyObject Object2){

}
        }

       //and then you can workaround this
        public static void main(String[] args) {
            MyResultObject resultOb = new MyResultObject(obj1,obj2,1);
            System.out.println(resultOb.getFirstObject() + resultOb.getSecondOBject());
        }