Java coding test

[Mohamed Farouk]

Hello Guys
In one of the interviews I went for Java development, I was asked to write code to add/Subtract/Multiply and Divide 2 numbers using OOPrinciples. We have to create classes like OO principle not just add/subtract/divide and multiply

I did design these classes and wrote something. But would reallly lie to hear from other experts on how they will design and implment this/

Interesting puzzle..

[Campbell Ritchie]

That sounds too serious to be a "diversion", so I shall move this thread. It doesn't mean you escape me as a mod, however.

public final class MyInteger
{
    private final int value;

    public MyInteger(int value)
    {
       this.value = value;
    }

    @Override public boolean equals(Object obj)
    {
        return obj instanceof MyInteger // Can use instanceof because final class
                  && (MyInteger)obj.value == this.value;
    }

    @Override public int hashCode()
    {
        return value + 31;
    }

    @Override public String toString()
    {
        return this.getClass().getSimpleName() + " " + value;
    }

    public MyInteger add(MyInteger other)
    {
        return new MyInteger(// You didn't think I would write anything here, did you?
    }
 . . .
    public . . . divide(MyInteger other)
    {
        if(other.value == 0) // work out what goes in here for yourself
        . . .
    }
}

Not only object-oriented, but immutable too It is actually a very simple exercise.