Question

class IfSample {
    public static void main(String args[]) {
        int x, y;
        x = 10;
        y = 20;
        if (x < y) System.out.println("x is less than y");
        x = x * 2;
        if (x == y) System.out.println("x is equal to y");
        x = x * 2;
        if (x > y) System.out.println("x is greater than y");
        if (x == y) System.out.println("x is equal to y");
    }
}

根据我的输出应该是

x小于y
  x等于y
  x等于y

但实际输出是

x小于y
  x等于y
  x大于y

请解释我怎么可能？

Answer 1

x = x * 2;实际上会将x * 2 的结果分配给 x。

你正在申请两次。所以x依次是10,20，然后是40。

它不会以某种方式重置为10。

随着您的进步，您可能会发现等效语句x *= 2;更清晰。我做。

Answer 2

我试着解释下面的代码，检查我的评论

class IfSample {
    public static void main(String args[]) {
        int x, y;//You created two variables
        x = 10;// 10 was assigned to variable x
        y = 20;// while 20 was assigned to variable y

        //you checked if x is less then y which is true cause 10 is less than 20
        if (x < y) System.out.println("x is less than y");

        x = x * 2;//You mutiplied x (which is 10) times 2 making x = 20

        //You checked if x is equal to y which is true cause x is now 20
        if (x == y) System.out.println("x is equal to y");

        x = x * 2;//You multiplied x (which is 20) by 2 given a new value of 40

        //You checked if 40 (x new value) is greater than y(value is 20) which is true
        if (x > y) System.out.println("x is greater than y");

        //This will be false cause 40 (x value) is not equal to 20 (y value) 
        if (x == y) System.out.println("x is equal to y");
    }
}

对于预期的输出，您需要这样做：

class IfSample {
    public static void main(String args[]) {
        int x, y;
        x = 10;
        y = 20;
        if (x < y) System.out.println("x is less than y");
        x = x * 2;
        if (x == y) System.out.println("x is equal to y");
        x = x * 2;
        y = y * 2;//Now y will be 40 (i.e 20 *2)
        if (x > y) System.out.println("x is greater than y");
        if (x == y) System.out.println("x is equal to y");
    }
}

Answer 3

在if (x > y) System.out.println("x is greater than y");

之前对于秒时间，

x乘以2。

因此20 * 2 = 40 ...大于y = 20。

注意：在第一次乘法10 * 2期间，结果值20存储在变量x（内存中的位置）中。

Answer 4

很简单，每次检查条件时，都要为＆＃39; x＆＃39;分配一个新值。将它乘以2。编译器逐行解释并设置最后分配的值。

Answer 5

当x = 10

时

new.target

所以首先它打印x小于比x = y 然后x大于y

简单地数学不是编程

Answer 6

x = 10且y = 20的初始值。执行if (x < y)后 X乘以2 i，e 10 * 2，所以现在x = 20 执行if (x == y)后 X再次乘以2 i，e 20 * 2，所以现在x = 40 所以if条件(x>y)即40> 20这是真的，因此它给出了预期的结果。

我是编程的新手，我无法理解这段代码

6 个答案: