java代码中的问号 [英] Question mark in java code

问题描述

有人可以在下面的代码中解释问号吗？此外，INITIAL_PERMANCE是代码中的静态最终常量，但synatax的最后一行是什么？

Can someone explain the question mark in the following code? Also INITIAL_PERMANCE is a static final constant in the code but what is the last line of synatax called?

Synapse(AbstractCell inputSource, float permanence) {
    _inputSource = inputSource;
    _permanence = permanence==0.0 ? 
        INITIAL_PERMANENCE : (float)Math.min(1.0,permanence);
}

推荐答案

？和：是java条件运算符的一部分。有时称为三元运算符，因为它是Java中唯一带有3个参数的运算符。

The ? and : are part of the java conditional operator. Sometimes called the ternary operator because it is the only operator in Java that takes 3 arguments.

这实际上是一个内联IF / THEN / ELSE块。

This is essentially an inline IF / THEN / ELSE block.

_permanence = permanence==0.0 ? 
    INITIAL_PERMANENCE : (float)Math.min(1.0,permanence);

可以按如下方式重写：

if (permanence == 0.0)
    _permanence = INITIAL_PERMANENCE;
else
    _permanence = (float) Math.min(1.0,permanence);

条件运算符的一般形式是

The general form of the conditional operator is

<Test returning a boolean> ? <value for if test is true> : <value for if test is false>

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