java为什么增量后操作符在此代码中无法增量“a”？

Question

package com;

public class Test {

    public static void main(String[] args)
    {
        int a= 11, b = 10;
        a = a++ + ++b;  //why? output is "22 11" and not "23 11"
        System.out.println(a+" "+b);

    }

}

Answer 1

下面是表达式的求值方式（大致上，我没有检查JLS的求值顺序，但我认为它是从左到右的）：

a = a++ + ++b;  // a is 11, b is 10
a = 11 + ++b;  // a is 12 but its previous value 11 was returned by a++, b is 10
a = 11 + 11;  // a is 12, b is 11 and its updated value was returned by ++b
a = 22;  // a is 12, b is 11 and its updated value was returned by ++b

因此，这是预期的结果，你只需要应用这些操作符的定义

Answer 2

a++意味着“a”在你写它的地方有旧的值，然后再修改++a表示“a”首先改变值，然后计算

So:
a = 5;
b = 5;
So:
a++ + ++b = (5 (and a + 1 later) + (at first b + 1) 6.

我希望你能理解我）我的英语水平与你的Java=）