Java CharAt（）和deleteCharAt（）性能 [英] Java CharAt() and deleteCharAt() performance

问题描述

我一直想知道java
中String / StringBuilder / StringBuffer的charAt函数的实现是什么？它的复杂性是什么？
还有什么关于StringBuffer / StringBuilder中的deleteCharAt（）？

I've been wondering about the implementation of charAt function for String/StringBuilder/StringBuffer in java what is the coomplexity of that ? also what about the deleteCharAt() in StringBuffer/StringBuilder ?

推荐答案

对于 String ， StringBuffer ， StringBuilder ， charAt（）是一个固定时间操作。

For String, StringBuffer, and StringBuilder, charAt() is a constant-time operation.

对于 StringBuffer 和 StringBuilder ， deleteCharAt（）是线性时间操作。

For StringBuffer and StringBuilder, deleteCharAt() is a linear-time operation.

StringBuffer 和 StringBuilder 具有非常相似的性能特征。主要区别在于前者是 synchronized （因此是线程安全的），而后者则不是。

StringBuffer and StringBuilder have very similar performance characteristics. The primary difference is that the former is synchronized (so is thread-safe) while the latter is not.

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