TL之StringBuilder构建字符串

最新推荐文章于 2021-02-26 22:26:50 发布

原创最新推荐文章于 2021-02-26 22:26:50 发布 · 138 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#算法 #JDK #C #C++ #C#

本文探讨了在Java中如何高效地构建字符串。使用String进行拼接会因频繁创建新对象而导致性能下降。文章介绍了StringBuilder类，它允许程序员在不创建新对象的情况下添加字符或字符串片段，从而提高性能并减少内存消耗。此外还对比了StringBuilder与StringBuffer的异同。

我们都知道怎样用String去构建字符串，但常常也会被一些细节困扰。由于Java语言给我们带来的很多方便，很多时候程序员也便渐渐不去考虑一些效率问题了。这远远不像曾经学C或C++的时候纠结算法，效率的抓狂年代。
最近开始下定决心仔细学习下Java基础知识部分，就把一些觉得比较容易被大家忽视，也同样是很重要的（只要你认为重要就好）知识点拿出来和大家资源共享一下。大多数是在《Core java》系列上整理和搜集下来的。
Why we talked about StringBuilder,why should wo use it?
Occasionally, you need to build up strings from shorter strings, such as keystrokes orwords from a file. It would be inefficient to use string concatenation for this purpose.
Every time you concatenate strings, a new String object is constructed. This is time consuming and it wastes memory. Using the StringBuilder class avoids this problem.
Follow these steps if you need to build a string from many small pieces. First, construc an empty string builder:
StringBuilder builder = new StringBuilder();
Each time you need to add another part, call the append method.
builder.append(ch); // appends a single character
builder.append(str); // appends a string
When you are done building the string, call the toString method. You will get a String
object with the character sequence contained in the builder.
String completedString = builder.toString();

那么StringBuffer呢？
The StringBuilder class was introduced in JDK 5.0. Itspredecessor, StringBuffer, is slightly less efficient, but it allows multiple threads to add or remove characters. If all string editing happens in a single thread (which is usually the case), you should use StringBuilder
instead. The APIs of both classes are identical.
要想更深地了解体会构建字符串的几种方式的区别，看看他们的API 然后敲上几行小代码测试下不就可以了哈？