Hi,

This is the specified behaviour of the operator ||, not of the if-statement.

Look at the Java Language Specification:

http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.24

It clearly says that " The |||| operator is like ||| (§15.22.2)
<http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#5242>,
but evaluates its right-hand operand only if the value of its left-hand
operand is |false|."

Cheers,

Jacques-Olivier

The 'if' statement is 'standardized', it has well defined behavior.

But what you are referring to, is the result of the || operator, i.e.
the conditional OR operator. The conditional OR doesn't evaluate its
right-hand expression when the left-hand expression is true (i.e.
evaluated to true).
However, the boolean OR operator, the | operator, does evaluate both
left- and right-hand expressions.

In the following code snippet, the first if statement completes
normally, but the second if, containing the | operator, throws a null
pointer exception.

      String myString = null;
      if (myString == null || myString.length() == 0)
      {
         System.out.println("Either myString was null, "
               + "or myString was an empty String");
      }
      if (myString == null | myString.length() == 0)
      {
         System.out.println("myString was null "
               + "or myString was an empty String");
      }

Similar things apply to the conditional AND operator (&&) and the
boolean AND operator (&).
<http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#54532>
<http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#5242>
<http://java.sun.com/docs/books/jls/second_edition/html/expressions.doc.html#5247>

Incidentally, this aspect of the Java definition is /extremely/ well-known (and
is common with C and C++ too),  There would not normally be any point in
addinng a comment explaining it.

For instance, the following code is sufficiently self-explanatory that there
would be no point in explaining that slowCheck() is only used if quickCheck()
fails:

   if (quickCheck() || slowCheck())
   {
       // ...whatever
   }

   -- chris

Ok, thanks everyone for your answers.

Daniel