字符串替换方法不替换字符 [英] String replace method is not replacing characters

问题描述

我有一个以字符串形式传递的句子，我正在对单词"and"进行替换，我想将其替换为".它并没有用空格代替和"一词.以下是我的逻辑示例.而且当我调试此命令时，逻辑确实落入了句子.替换.

I have a sentence that is passed in as a string and I am doing a replace on the word "and" and I want to replace it with " ". And it's not replacing the word "and" with white space. Below is an example of my logic. And when I debug this the logic does fall into the sentence.replace.

String sentence = "Define, Measure, Analyze, Design and Verify"
if (sentence.contains("and")){
    sentence.replace("and", " ");
}

这里有我想念的东西吗?

Is there something I am missing here.

推荐答案

当我调试它时，逻辑确实落入了句子.替换.

And when I debug this the logic does fall into the sentence.replace.

是，然后您放弃返回值.

Yes, and then you discard the return value.

字符串是不可变的-调用replace时，它不会更改 existing 字符串的内容-它会返回经过修改的 new 字符串.所以你想要:

Strings in Java are immutable - when you call replace, it doesn't change the contents of the existing string - it returns a new string with the modifications. So you want:

sentence = sentence.replace("and", " ");

这适用于 all 字符串中的方法(substring，toLowerCase等).它们中的 None 都不会更改字符串的内容.

This applies to all the methods in String (substring, toLowerCase etc). None of them change the contents of the string.

请注意，您实际上并不需要在某种情况下执行此操作-毕竟，如果句子不包含"and"，则执行替换无害:

Note that you don't really need to do this in a condition - after all, if the sentence doesn't contain "and", it does no harm to perform the replacement:

String sentence = "Define, Measure, Analyze, Design and Verify";
sentence = sentence.replace("and", " ");

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