How to use operations like +-*/ on java-objects

Question

I need to program a java-class "Fraction".

This class should be able to understand the basic arithmetic operations like +, -, *, /. I found lots of "Fraction" classes and understand them, but all use methods like "f1.add(f2);" (f1, f2 are objects of Fraction, for Example:

f1 = new Fraction(1,5);
f2 = new Fraction(2,5);

What I need is a direct manipulation like the manipulation of integers, for example:

**f1 = f1 + f2;**

instead of

f1.add(f2);

Why do you *need* it? The methods do the same thing and work fine. — asteri, Jun 04 '13 at 15:41

score 6 · Answer 1 · answered Jun 04 '13 at 15:34

6

You can't: java doesn't allow overloading operators.

answered Jun 04 '13 at 15:34

eternay

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Thanks for that answer. So I will have to try out a new programming language :/ Someone has an advice for me? C#, C++? Perhaps PHP? – user2452336 Jun 04 '13 at 15:38

score 1 · Answer 2 · answered Jun 04 '13 at 16:06

This is not possible in standard Java.

As you have asked explicitly in a comment: I suggest Scala (in contrast to Groovy), because it's type-safe (among many other advantages), and it is a JVM language as well:

class Fraction(val n: Int, val d: Int) {
  override def toString = s"$n/$d"

  def +(that: Fraction) = new Fraction(this.n + that.n, this.d)
}

object FractionDemo extends App {
  val f1 = new Fraction(1, 4)
  val f2 = new Fraction(2, 4)
  val f3 = f1 + f2
  println(s"$f1 + $f2 = $f3")
}

and the output is

1/4 + 2/4 = 3/4

I know that + is not implemented correctly, this is just a small example.

If you are interested in a numerical library for Scala, have a look at spire, it already has a Fractional class.

score 0 · Answer 3 · answered Jun 04 '13 at 15:40

0

As eternay said, Java doesn't support operator overloading. You could look at Groovy.It is a Java-like JVM-based language which does support operator overloading.

answered Jun 04 '13 at 15:40

stinepike

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score 0 · Answer 4 · edited May 23 '17 at 11:57

0

If you're interested in a language based in JVM that support operator overloading you can try Groovy. See here some discussion: Operator overloading in Java

edited May 23 '17 at 11:57

Community

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answered Jun 04 '13 at 15:41

Paolof76

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How to use operations like +-*/ on java-objects

4 Answers4