java 如何检查字符串是否多次包含相同的字母？
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How do I check if a String contains the same letter more than once?
提问by rednaxela
I'm a bit confused in how I would check if a String contains the same letter more than once.
我对如何检查 String 是否多次包含相同的字母感到有些困惑。
ArrayList<String> words = new ArrayList<String>();
words.add("zebra");
words.add("buzzer");
words.add("zappaz");
Let's say I only want to print out any words which contain more than one "z", therefore only "buzzer" and "zappaz" would get printed. How would I do this?
假设我只想打印包含多个“z”的任何单词，因此只会打印“蜂鸣器”和“zappaz”。我该怎么做？
回答by Denys Séguret
To test if a string contains two z, you can do this :
要测试字符串是否包含两个 z，您可以这样做：
boolean ok = word.matches(".*z.*z.*")
回答by Ry-
indexOfreturns the... index of... a character in a string. It also takes an optional argument specifying where to search. If there is no match, it returns -1. So just use it twice:
indexOf返回... 字符串中字符的... 索引。它还需要一个可选参数来指定搜索位置。如果没有匹配项，则返回-1。所以只需使用它两次：
s.indexOf(letter, s.indexOf(letter) + 1) > -1
(For efficiency's sake, though, may as well check the first result.)
（不过，为了效率，不妨检查第一个结果。）
回答by Thomas Jungblut
A smart solution could be, removing the character you want to search and compare the length of the resulting string with the complete string.
一个聪明的解决方案可能是，删除要搜索的字符并将结果字符串的长度与完整字符串进行比较。
ArrayList<String> words = new ArrayList<String>();
words.add("zebra");
words.add("buzzer");
words.add("zappaz");
for (String word : words) {
// calculate the length difference
if (word.length() - word.replace("z", "").length() > 1) {
System.out.println(word);
}
}
will print:
将打印：
buzzer
zappaz
Not very efficient, but it works and is pretty simple.
不是很有效，但它有效并且非常简单。
回答by someone
public static void main(String[] args) {
String s = "bazzer";
String news = s.replaceAll("z", "");
if(news.length() < s.length() -1 ){
System.out.println(s);
}
}
