这 ！ 和 && 运算符 Java

Question

Ok so, I was working on a program and I ran into a little problem/question.

Eg

int num1 = 3, int num2 =0;   
while (!num1 == 1 && num2 == 0)
    { 
      ...
    }

Does the ! apply to the whole statment in, or only to the part before && ?

Answer 1

The ! part actually only applies to the num1 integer (Which is surely not what you want), not even the num1 == 1 part.

So your expression is basically,

if (((!num1) == 1) && (num2 == 0)) {

Answer 2

The ! is applied before the && according to the Java order of operations , so the ! only applies to the part before the && .

Answer 3

Use IDE such as Eclipse and set Compiler compliance levels to latest Java versions. You will get errors to help you make the right decision.

And if you want to read how precedence works, then follow the official Java reference link here: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/operators.html