Non-short-circuit Operator

Expression	Result	Evaluation Order
true && true	true	both operands evaluated
false && true	false	only first operand evaluated
true && false	false	both operands evaluated
false && false	false	only first operand evaluated
true & true	true	both operands evaluated
false & true	false	both operands evaluated
true & false	false	both operands evaluated
false & false	false	both operands evaluated

The & operator combines two boolean values using the rules for AND, but always evaluates both operands. This is useful when you want both operands to be evaluated no matter what values are returned.

The disadvantage is a possible loss of speed. Most Java programs are written using the && operator whenever an AND is needed. The programmer must be careful of side-effects, though. Usually this is done by writing methods that are "pure functions" as much as possible. A pure function is a method that returns a value and is free of side effects. Methods that are not pure functions should usually be kept out of boolean expressions.

For example, the final version of the method computeMaximum() in the previous example is a pure function. It computed the maximum, but did not itself save the result.

int count = 0;     // say that these values are the result of
int total = 345;   // the program running with input data.

if ( count > 0 && total / count > 80 )
  System.out.println("Acceptable Average");
else
  System.out.println("Poor Average");