boolean a, b;
Operation Meaning Note
--------- ------- ----
a && b logical AND short-circuiting
a || b logical OR short-circuiting
a & b boolean logical AND not short-circuiting
a | b boolean logical OR not short-circuiting
a ^ b boolean logical exclusive OR
!a logical NOT
short-circuiting (x != 0) && (1/x > 1) SAFE
not short-circuiting (x != 0) & (1/x > 1) NOT SAFE
int a = 4;
int b = 7;
System.out.println(a & b); // prints 4
//meaning in an 32 bit system
// 00000000 00000000 00000000 00000100
// 00000000 00000000 00000000 00000111
// ===================================
// 00000000 00000000 00000000 00000100
< p >除了,,||为短路,在混合两种形式时也要考虑运算符优先级。
我认为每个人都不会立即看出result1和result2包含不同的值
boolean a = true;
boolean b = false;
boolean c = false;
boolean result1 = a || b && c; //is true; evaluated as a || (b && c)
boolean result2 = a | b && c; //is false; evaluated as (a | b) && c
int numberOne = 1;
int numberTwo = 2;
boolean result = false;
// left-side is false so the the overall result CAN be predicted without evaluating the right side.
// numberOne will be 1, numberTwo will be 2, result will be false
result = (numberOne > numberTwo) && (++numberOne == numberTwo);
System.out.println(numberOne); // prints 1
System.out.println(numberTwo); // prints 2
System.out.println(result); // prints false
// left-side is true so the the overall result CAN NOT be predicted without evaluating the right side.
// numberOne will be 2, numberTwo will be 2, result will be true
result = (numberTwo > numberOne) && (++numberOne == numberTwo);
System.out.println(numberOne); // prints 2
System.out.println(numberTwo); // prints 2
System.out.println(result); // prints true
& | ^完全评估
虽然在某些情况下可以预测结果,但有必要计算右边的值。
int numberOne = 1;
int numberTwo = 2;
boolean result = false;
// left-side is false so the the overall result will be false BUT the right side MUST be evaluated too.
// numberOne will be 2, numberTwo will be 2, result will be false
result = (numberOne > numberTwo) & (++numberOne == numberTwo);
System.out.println(numberOne); // prints 2
System.out.println(numberTwo); // prints 2
System.out.println(result); // prints false