Why is is not possible to test anything other than a boolean?

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Why boolean in Java takes only true or false? Why not 1 or 0 also?

I was wondering today why Java cannot test any other type than a boolean.

In C, C++ and many other languages (actually most programming languages), the following is possible and valid:

int a = 0;
if (a) // evaluates to false
  ; // do something nice

a = 6;
if (a) // evaluates to true
  ; // do something more

This also works almost everywhere for objects, arrays; anything that can have a value of 0x00000000 in the memory.

The question: why is this not possible in Java (you have to keep on testing for == 0 or == null)?

Because that's how Java is. I'd also posit that an if statement is intrinsically boolean by nature, a number isn't really boolean, hence using a number as a boolean wouldn't really be considered type-appropriate. — Dave Newton, May 15 '12 at 15:52
Because it is meaningless to evaluate anything other than a boolean in an `if` condition. — adarshr, May 15 '12 at 15:54

score 0 · Answer 1 · answered May 15 '12 at 15:52

0

Because James Gosling et al decided that Java wouldn't do that.

answered May 15 '12 at 15:52

mcfinnigan

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score 0 · Accepted Answer · answered May 15 '12 at 15:52

I would guess that the rationale why is because it simplifies things.

An if statement has to evaluate a value to one of two possible conditions. What Java does is require you to supply a statement itself that must evaluate to two possible conditions (boolean) rather than accept other values and arbitrarily decide if that evaluates to true or false.

Why is is not possible to test anything other than a boolean?

2 Answers2