java - 读取和解释程序中的逻辑表达式

Question

您通常如何阅读程序中的逻辑表达式？例如:

(1 == x) && ( 2 > x++)? (x=1)

的目的是什么？表达式正确答案的生成思路是什么？

Answer 1

下面的语句:

var value = (boolean expression) ? some value if `true` : some value if `false`

是一个特殊的条件语句，它使用了 Ternary Operator (?:) 根据 boolean 表达式为变量赋值。

这是表达此条件语句的更简洁的方式:

var value;

//this is the boolean expression you evaluate before the question mark
if (boolean expression is true) {
    //this is what you assign after the question mark
    value = some value if true;
}
else {
    //this is what you assign after the colon
    value = some other value if false;
}

因此，根据您的示例(顺便说一句，语法错误)，这将类似于:

if ((1 == x) && (2 > x++)){
    x = 1;
}
else {
    /*This is the value that would be put after the colon
     *(which is missing in your example, and would cause a compiler error)
     */
    x = some other value; 
}

这将转化为:

x = (1 == x) && (2 > x++) ? 1 : some other value