布尔值和 == vs =

Boolean and == vs =(布尔值和 == vs =)

问题描述

语言是Java.鉴于此:

The language is Java. Given this:

public static void main(String[] args) {
    Boolean b1 = true;
    Boolean b2 = true;
    int i1 = 1;

    if (b1 = true) //line 5
    if (b1 == true}  // line 6

我知道 b1 == true 是一个等效的测试，它会给出结果:真或假.但是，对于 b1 = true ，据我了解是一个声明，除了在这种情况下，它应该什么都不返回: b1 = true 返回 true，与 == 测试?

I understand that b1 == true is a equivalent test , which will give the result : true OR false. However, with b1 = true , which to my understanding is a declaration, which should return nothing but in this case : b1 = true returns true, exactly the same as == test?

你能解释一下为什么吗?谢谢！

Can you explain why? Thanks!

推荐答案

if (identifier = literal) 计算结果为:

identifier = literal;  
if (identifier)

首先将文字分配给标识符.然后你在分配后测试它

first you assign the literal to the identifier. then you test it post assignment

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