Logical Operators

There are three logical operators in Java and are evaluated in the following order:

!     The not operator     !true  is false   !false is the value true
&&    The and operator     true && true  is true, other cases return false
||    The or operator      false || false is false, other cases return true


!value    result
------    ------
!true     false
!false    true



value &&  value   result
-----     -----   ------
true  &&  true    true
true  &&  false   false
false &&  true    false
false &&  false   false




value ||  value   result
-----     -----   ------
true  ||  true    true
true  ||  false   true
false ||  true    true
false ||  false   false


Examples:





if (!(x>y))
   ...
   
if ( x>y && x>z)
   ...
   
if (x<y || x<z)
   ...
      
if (x > y)
   out.println("x is greater than y");
			
if (y > x)
   out.println("y is greater than x");
			

if (x > y && x > z)
   out.println("x is greater than y and z");
else if (y > z)
   out.println("y is greater than x and z");
else
   out.println("z is greater than x and y");


Note:  && and || operators are short circuited (the right side is not evaluated unless necessary).
       For example: 
	   if the left side of an || operation is true, there is no need to evaluate the right hand side.
	   if the left side of an && operation is false, there is no need to evaluate the right hand side.