字符串中所有出现的字符的索引 [英] Indexes of all occurrences of character in a string

问题描述

下面的代码会打印2

String word = "bannanas";
String guess = "n";
int index;
System.out.println( 
    index = word.indexOf(guess)
);

我想知道如何获取字符串banannas"中所有n"(猜测")的索引

I would like to know how to get all the indexes of "n" ("guess") in the string "bannanas"

预期结果是:[2,3,5]

推荐答案

这应该在 Peter Lawrey 的解决方案 已经了.

int index = word.indexOf(guess);
while (index >= 0) {
    System.out.println(index);
    index = word.indexOf(guess, index + 1);
}

它也可以作为 for 循环来完成:

It can also be done as a for loop:

for (int index = word.indexOf(guess);
     index >= 0;
     index = word.indexOf(guess, index + 1))
{
    System.out.println(index);
}

[注意:如果guess可以长于一个字符，那么可以通过分析guess字符串，遍历word代码> 比上述循环快.这种方法的基准是 Boyer-Moore 算法.然而，支持使用这种方法的条件似乎不存在.]

[Note: if guess can be longer than a single character, then it is possible, by analyzing the guess string, to loop through word faster than the above loops do. The benchmark for such an approach is the Boyer-Moore algorithm. However, the conditions that would favor using such an approach do not seem to be present.]

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