[英]When to use String#concat() method in Java?
I've been through different topics about String concatenation performance.我已经了解了有关字符串连接性能的不同主题。 Almost answer recommend using
StringBuilder
or StringBuffer
to reduce overhead cost (or +
operator if concatenation statement outside the loop).几乎答案建议使用
StringBuilder
或StringBuffer
来减少开销成本(如果连接语句在循环外,则为+
运算符)。 It's pretty clear, but I still wonder why Java has String format()
and concat()
method although it's ineffective.很清楚,但我仍然想知道为什么 Java 有 String
format()
和concat()
方法,尽管它无效。 Performance test here: link .性能测试在这里:链接。 Someone mentioned String
format()
may be useful for Localization
purpose (I don't understand much, howsoever I already have a keyword to search later), but what's the purpose of the remaining one?有人提到 String
format()
可能对Localization
目的有用(我不太明白,但是我已经有一个关键字可以稍后搜索),但剩下的一个目的是什么? Does it only useful for compatibility backward?它仅对向后兼容有用吗?
String#concat
and +
exist to provide a minimalistic set of operations on the type String. String#concat
和+
存在是为了在类型 String 上提供一组简约的操作。
They are not efficient if used multiple times.如果多次使用,它们效率不高。
But they have their own right as type operations "xxx" + "yyy"
you do not want to specify using a StringBuilder.但是他们有自己的权利,因为您不想使用 StringBuilder 指定类型操作
"xxx" + "yyy"
。 (Furthermore there it is a compile time concatenation.) (此外,它是一个编译时串联。)
StringBuffer
is a mistake IMHO. StringBuffer
是一个错误恕我直言。 It is slower that the newer StringBuilder
as it is synchronized, but one would rarely add something rom two threads (unordered).较新的
StringBuilder
较慢,因为它是同步的,但很少会在两个线程(无序)中添加一些东西。
String::concat
may be a method reference useful for stream reduction or such. String::concat
可能是对流减少等有用的方法引用。
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