查找Java String中出现的字符 [英] Find occurrences of characters in a Java String

问题描述

我想计算字符串中字符的出现次数，假设我有字符串aaaab，我如何计算其中的数量？

I would like to count the occurrences of a character in a string, suppose I have the string "aaaab", how would i count the amount of a's in it?

推荐答案

如果不使用正则表达式，代码看起来更容易阅读。

The code looks way easier to read if you don't use regular expressions.

int count = 0;
for(int i =0; i < string.length(); i++)
    if(string.charAt(i) == 'a')
        count++;

count 现在包含'a'的数量在你的字符串中。并且，这在最佳时间内执行。

count now contains the number of 'a's in your string. And, this performs in optimal time.

正则表达式适用于模式匹配。但只需一个常规循环即可完成工作。

Regular expressions are nice for pattern matching. But just a regular loop will get the job done here.

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