CODEWITHSUNDEEP
javaoperator-precedence
Szymon Toda
Szymon Toda

Reputation: 4516

Java OR operator precedence

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 ||

Upvotes: 9

Views: 64516

Answers (5)

Silly Freak
Silly Freak

Reputation: 4231

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.

Upvotes: 14

Rakesh Chaudhari
Rakesh Chaudhari

Reputation: 3500

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

Upvotes: 1

Mitesh Pathak
Mitesh Pathak

Reputation: 1306

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

Upvotes: 0

Weibo Li
Weibo Li

Reputation: 3605

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

Upvotes: 2

Roy
Roy

Reputation: 3624

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.

Upvotes: 0

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