Java字符串：compareTo（）与equals（） [英] Java Strings: compareTo() vs. equals()

问题描述

在Java中测试 String 的相等性时，我总是使用 equals（）因为对我这个似乎是最自然的方法。毕竟，它的名字已经说明了它的目的。然而，我最近告诉我的一位同事被教导使用 compareTo（）== 0 而不是 equals（）。这感觉不自然（因为 compareTo（）意味着提供排序而不是比较相等）甚至有些危险（因为 compareTo（）== 0 并不一定意味着在所有情况下都是平等的，即使我知道它对我来说也是 String '。

When testing for equality of String's in Java I have always used equals() because to me this seems to be the most natural method for it. After all, its name already says what it is intended to do. However, a colleague of mine recently told me had been taught to use compareTo() == 0 instead of equals(). This feels unnatural (as compareTo() is meant to provide an ordering and not compare for equality) and even somewhat dangerous (because compareTo() == 0 does not necessarily imply equality in all cases, even though I know it does for String's) to me.

他不知道为什么他被教导使用 compareTo（）而不是 equals（） for String ，我也找不到任何理由。这真的是个人品味的问题，还是有任何方法的真正原因？

He did not know why he was taught to use compareTo() instead of equals() for String's, and I could also not find any reason why. Is this really a matter of personal taste, or is there any real reason for either method?

推荐答案

区别在于foo.equals（（String）null）返回false，而foo.compareTo（（String）null）== 0 抛出NullPointerException。因此，即使对于Strings，它们也不总是可以互换的。

A difference is that "foo".equals((String)null) returns false while "foo".compareTo((String)null) == 0 throws a NullPointerException. So they are not always interchangeable even for Strings.

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