Java while 循环布尔计算

Java while loop boolean evaluation

提问by user3401960

I am not sure if i understand this loop

我不确定我是否理解这个循环

boolean b = false;
while(!b) {
System.out.println(b);
b = !b;
}

it returns a false, loop is executed once

它返回一个错误，循环执行一次

but does while(!b)set b= true? like !b = !falseand bis printed out?

但是while(!b)设置了b= true吗？喜欢!b = !false并b打印出来？

回答by Mena

The while (!b)condition does not set bto true.

该while (!b)条件不设置b到true。

The b = !bstatement does.

该b = !b声明一样。

That's why your loop executes only once.

这就是为什么你的循环只执行一次。

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Translation in pseudo-code:

伪代码翻译：

• while not b(that is, while bis false)
• print b(so print false)
• assign bto not b, that is, the opposite of b(so assign bto true)
• next iteration of the loop, bis true, so not bcondition fails and loop terminates

• while not b(即 while bis false)
• 打印b（所以打印false）
• 分配b给not b，即b（所以分配b给true）的反义词
• 循环的下一次迭代b是true，所以not b条件失败并且循环终止

回答by Kick

while(!b) {    // As b = false but due to ! condition becomes true not b
System.out.println(b);  //false will be printed
b = !b;  // b = !false i.e. now b is true 
}

As now bis true so in next iteration the condition will be false and you will exist from loop

因为现在b为真，所以在下一次迭代中，条件将为假，您将从循环中存在

回答by PeterMmm

!is the negation unary operator in Java a do not modify the operand.

!是 Java 中的否定一元运算符 a 不修改操作数。

回答by T McKeown

Translated:

翻译：

 boolean b = false;
 while(b == false) {
 System.out.println(b);
 b = !b;  // b becomes true
}

回答by Dr. Collage

boolean b = false;
while(!b) { // The !b basically means "continue loop while b is not equal to true"
System.out.println(b);
b = !b; // this line is setting variable b to true. This is why your loop only processes once.
}