Lets say I have this:
if(bool1 && bool2 && bool3) {
...
}
Now. Is Java smart enough to skip checking bool2 and bool2 if bool1 was evaluated to false? Does java even check them from left to right? I'm asking this because i was "sorting" the conditions inside my if's by the time it takes to do them (starting with the cheapest ones on the left). Now I'm not sure if this gives me any performance benefits because i don't know how Java handles this.
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Is Java smart enough to skip checking bool2 and bool2 if bool1 was evaluated to false?
Its not a matter of being smart, its a requirement specified in the language. Otherwise you couldn't write expressions like.
if(s != null && s.length() > 0)
or
if(s == null || s.length() == 0)
BTW if you use &
and |
it will always evaluate both sides of the expression.
Yes,that is called short-circuiting.
Please take a look at this wikipedia page on short-circuiting
Please look up the difference between &
and &&
in Java (the same applies to |
and ||
).
&
and |
are just logical operators, while &&
and ||
are conditional logical operators, which in your example means that
if(bool1 && bool2 && bool3) {
will skip bool2
and bool3
if bool1
is false, and
if(bool1 & bool2 & bool3) {
will evaluate all conditions regardless of their values.
For example, given:
boolean foo() {
System.out.println("foo");
return true;
}
if(foo() | foo())
will print foo
twice, and if(foo() || foo())
- just once.
Source: Stackoverflow.com