Function returning two reference variables

[Jacob Sonia]

    

class A1{
Long first = A;
Short second = B;
TwoReturnValues value = new Class B1().new ReturnValues(A,B);
value = new Class B1().persist(value.getFirst(), value.getSecond());
first = value.getFirst();
second = value.getSecond();
//do soemthing with the values
}


class B1{
public final class TwoReturnValues {
	
	public final R first;
	public final S second;
	
	public TwoReturnValues(R first, S second) {
		this.first = first;
		this.second = second;
	}
	
	public R getFirst() {
		return first;
	}
	
	public S getSecond() {
		return second;
	}
}

public TwoReturnValues persist(First A, Second B){
TwoReturnValues value = new ReturnValues(A,B);
return value;
}
}

Please guide me if i should use array to return tow reference variables or inner class is better? Which is considered good coding skills?

[David Newton]

Depends. If the returned types are two unrelated types then you'd have to return an Object[], which negates the value of type safety, IDE support, etc. I tend to use inner classes or utility classes instead--but that's just me.

[Jim Hoglund]

Objects that manage pairs of items or values are quite
common. They are also easy to expand (extend) to handle
more items and mixed item types. So by using an object
you are on a very good track.
Jim ... ...

[Jacob Sonia]

But should i use a collection or just an object array would suffice for two objects

[Campbell Ritchie]

I would use an object which encapsulates the two values, not an array or collection.

[Jesper de Jong]

If I'd really need a method to return two values, I'd write a generic class Pair, something like this:

public class Pair<A, B> {
	private A first;
	private B second;

	public Pair(A first, B second) {
		this.first = first;
		this.second = second;
	}

	public A getFirst() {
		return first;
	}

	public B getSecond() {
		return second;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof Pair) {
			Pair other = (Pair) obj;
			return other.first.equals(first) && other.second.equals(second);
		}
		else {
			return false;
		}
	}

	@Override
	public int hashCode() {
		return first.hashCode() + second.hashCode();
	}
}

And make a method which returns a Pair of the types that you want, for example:

public Pair<Integer, String> method() {
	return new Pair<Integer, String>(24, "JavaRanch");
}

[Jacob Sonia]

What advantage this has over using Object array. I agree there is type checking and meaningful getters. But, for one time returning of two objects, which is preferable. I mean, i would like to know the pros and cons of each

[David Newton]

I think that's already been answered, no? What else do you want to know?

[fred rosenberger]

if you return an array, then your code will be sprinkled with

if (<need type A>)
{
    call (A)array[0].method1();
}
else if (<need type B>)
{
    call (B)array[1]].method2();
}

//or something like that - i may have the casting wrong

If you write a new class that encapsulates both A and B as member objects, you could write that containing class so that it knows what method to call...

  
public class MyEncapsulationClass
{
   private A myA;
   private B myB;

   public void method1()
   {
       myA.method1();
   }

   public void method2()
   {
       myB.method2();
   }

  public void method3()
  {
      if (myA != null)
      {
          myA.method3();
      }
      else if (myB != null)
      {
          myB.method3()
      }
      else
      {
          System.out.println("I don't have an A object or a B object");
      }
  }

}
  

[Sha Jar]

Jacob Sonia wrote:[code]
Which is considered good coding skills?

The general rule is that a method should return a value of a specific type.