How does Java deal with multiple conditions inside a single IF statement

Question

Lets say I have this   if bool1  amp  amp  bool2  amp  amp  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

User · Answer

Yes that is called short-circuiting   Please take a look at this wikipedia page on short-circuiting

User · Answer

Please look up the difference between  amp  and  amp  amp  in Java  the same applies to   and        amp  and   are just logical operators  while  amp  amp  and    are conditional logical operators  which in your example means that  if bool1  amp  amp  bool2  amp  amp  bool3      will skip bool2 and bool3 if bool1 is false  and  if bool1  amp  bool2  amp  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

User · Answer

Yes  Java  similar to other mainstream languages  uses lazy evaluation short-circuiting which means it evaluates as little as possible   This means that the following code is completely safe   if p    null  amp  amp  p getAge    gt  10    Also  a    b never evaluates b if a evaluates to true

User · Answer

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  amp  amp  s length    gt  0    or  if s    null    s length      0    BTW if you use  amp  and   it will always evaluate both sides of the expression

[java] How does Java deal with multiple conditions inside a single IF statement

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