Does the Java operator apply or

Question

Assuming  boolean a   false    I was wondering if doing   a  amp   b     is equivalent to  a   a  amp  amp  b    logical AND  a is false hence b is not evaluated    or on the other hand it means  a   a  amp  b    Bitwise AND  Both a and b are evaluated

User · Answer

It s the last one   a   a  amp  b

User · Answer

Here s a simple way to test it   public class OperatorTest            public static void main String   args            boolean a   false          a  amp   b               private static boolean b             System out println  b   was called            return true            The output is b   was called  therefore the right-hand operand is evaluated   So  as already mentioned by others   a  amp   b is the same as a   a  amp  b

User · Answer

i came across a similar situation using booleans where I wanted to avoid calling b   if a was already false   This worked for me   a  amp   a  amp  amp  b

User · Answer

see 15 22 2 of the JLS   For boolean operands  the  amp  operator is boolean  not bitwise   The only difference between  amp  amp  and  amp  for boolean operands is that for  amp  amp  it is short circuited  meaning that the second operand isn t evaluated if the first operand evaluates to false    So in your case  if b is a primitive  a   a  amp  amp  b  a   a  amp  b  and a  amp   b all do the same thing

User · Answer

From the Java Language Specification - 15 26 2 Compound Assignment Operators      A compound assignment expression of the form E1 op  E2 is equivalent to E1    T   E1  op  E2    where T is the type of E1  except that E1 is evaluated only once    So a  amp   b  is equivalent to a   a  amp  b     In some usages  the type-casting makes a difference to the result  but in this one b has to be boolean and the type-cast does nothing    And  for the record  a  amp  amp   b  is not valid Java   There is no  amp  amp   operator     In practice  there is little semantic difference between a   a  amp  b  and a   a  amp  amp  b     If b is a variable or a constant  the result is going to be the same for both versions   There is only a semantic difference when b is a subexpression that has side-effects   In the  amp  case  the side-effect always occurs   In the  amp  amp  case it occurs depending on the value of a    On the performance side  the trade-off is between the cost of evaluating b  and the cost of a test and branch of the value of a  and the potential saving of avoiding an unnecessary assignment to a   The analysis is not straight-forward  but unless the cost of calculating b is non-trivial  the  performance difference between the two versions is too small to be worth considering

[java] Does the Java &= operator apply & or &&?

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