在Java中将long转换为String的有效方法
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Efficient way to convert long to String in Java
提问by Matthew
I've been using
我一直在用
long a = 123456789;
String b = a+"";
to convert a longvalue (or int) to String, or in this perspective, treat it as String. My question is, is it ok to do this? Are there any negative impact?
将long值（或int）转换为String，或者从这个角度来看，将其视为字符串。我的问题是，这样做可以吗？有没有负面影响？
And is there any difference in using String.valueOf()vs Long.toString()?
使用String.valueOf()vs有什么区别Long.toString()吗？
Thanks
谢谢
采纳答案by daz
It is ok to do this as recent JVM will likely reduce it to:
这样做是可以的，因为最近的 JVM 可能会将其减少为：
String b = String.valueOf(a);
As for negatives, it is not good Java coding style as there is ambiguity. If awas null, would b = "null"? or will an NPE be thrown? You know the answer with experience, but this should be obvious to all readers of your code.
至于否定，它不是好的 Java 编码风格，因为存在歧义。如果a为null，那么b = "null"吗？还是会抛出 NPE？您凭经验知道答案，但这对于您的代码的所有读者来说应该是显而易见的。
回答by Konstantin Yovkov
First, your code doesn't compile - you have to append an Lafter the literal:
首先，您的代码无法编译 - 您必须L在文字后附加一个：
Long a = 123456789L;
String.valueOf()and Long.toString()methods both have a primitive longas a parameter, but since ais an wrapper (Long), you can just use the Object#toString()method:
String.valueOf()和Long.toString()方法都有一个原语long作为参数，但由于a是一个包装器 ( Long)，你可以只使用该Object#toString()方法：
String b = a.toString();
If a, however, is a primitive (long), both String.valueOf()and Long.toString()will do the same, so it's a matter of preference which one to use.
a但是，如果是原始类型 ( long)，则String.valueOf()和Long.toString()都会执行相同的操作，因此使用哪个是首选问题。
