Java OR operator precedence

Question

How to chain conditional statements in Java in a way that if b is false, than do not check c?

If a and c are false, and b is true, does c will be checked?

if (a || b || c)

I am looking for similar feature that PHP holds with difference between OR and ||

No, || does short circuit evaluation. So if a is false, b will be checked and if b is true, c won't be checked. If you're not sure, you can always test : http://ideone.com/mCE8hy — Alexis C., Jan 18 '14 at 09:42

score 14 · Accepted Answer · edited May 11 '18 at 15:54

14

The Java || operator (logical or operator) does not evaluate additional arguments if the left operand is true. If you wanted to do that, you can use | (bitwise or operator), although, according to the name, this is a little of a hack.

http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.23

Thus, && computes the same result as & on boolean operands. It differs only in that the right-hand operand expression is evaluated conditionally rather than always.

http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.24

Thus, || computes the same result as | on boolean or Boolean operands. It differs only in that the right-hand operand expression is evaluated conditionally rather than always.

Extra: it is considered bad programming style to depend on these semantics to conditionally call code with side effects.

edited May 11 '18 at 15:54

Michał Zaborowski

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answered Jan 18 '14 at 09:43

Silly Freak

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Sometimes it's needed if you want to squeeze performance out of your program – Szymon Toda Jan 18 '14 at 09:47
ah, I thought you were talking about `if(isAlright || doSomething()) ...` and not about `if(firstCondition || expensiveSecondCondition()) ...`. The first is a method with side effects, the second is just an expensive function without side effect. I'd say that the second one is fine anyway. – Silly Freak Jan 18 '14 at 09:56
Still it's shady and not readable-frendly but still sometimes you just have to meet the specs ;-) – Szymon Toda Jan 18 '14 at 10:05

score 2 · Answer 2 · answered Jan 18 '14 at 09:48

c won't be checked. To prove this, you can use the following code:

boolean a() {
  System.out.println("a")
  return false;
}

boolean b() {
  System.out.println("b")
  return true;
}

boolean c() {
  System.out.println("c")
  return true;
}

void test() {
  if(a() || b() || c()) {
    System.out.println("done")
  }
}

The output will be:

a
b
done

score 1 · Answer 3 · answered Aug 29 '17 at 09:43

1

if (a || b || c)

for you case,

a is true then b and c not checked.

a is false and b is true then c not checked.

a and b are false then c is checked.

the left side of the operator is evaluated first

answered Aug 29 '17 at 09:43

Rakesh Chaudhari

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score 0 · Answer 4 · edited May 23 '17 at 12:09

0

If a is false and b is true, then c will not be evaluated.

See this answer that addresses short circuiting of logical operators in Java.

edited May 23 '17 at 12:09

Community

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answered Jan 18 '14 at 09:43

Roy

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score 0 · Answer 5 · edited May 23 '17 at 12:25

1) How to chain conditional statements in Java in a way that if b is false, than do not check c?

Why do you need that?? it kills OR logic - neways c then is immaterial
so your answer simply is if (a || b)
or may be you are looking for if (a || (b && c))

2) If a and c are false, and b is true, does c will be checked? [ if (a || b || c) ]

Nope
|| does short circuit evaluation. So if a is false, b will be checked and if b is true, c won't be checked

For more on short circuit evaluation: refer

Java OR operator precedence

5 Answers5

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