在 Java 中查找字符串中子字符串的第二次出现
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Finding second occurrence of a substring in a string in Java
提问by AmanArora
We are given a string, say, "itiswhatitis"and a substring, say, "is".
I need to find the index of 'i'when the string "is"occurs a second time in the original string.
我们得到一个字符串，例如，"itiswhatitis"和一个子字符串，例如，"is"。我需要找到'i'字符串"is"在原始字符串中第二次出现的索引。
String.indexOf("is")will return 2 in this case. I want the output to be 10 in this case.
String.indexOf("is")在这种情况下将返回 2。在这种情况下，我希望输出为 10。
采纳答案by Rohit Jain
回答by Jeroen Vannevel
int first = string.indexOf("is");
int second = string.indexOf("is", first + 1);
This overload starts looking for the substring from the given index.
此重载开始从给定索引中查找子字符串。
回答by Pravat Panda
i think a loop can be used.
我认为可以使用循环。
1 - check if the last index of substring is not the end of the main string.
2 - take a new substring from the last index of the substring to the last index of the main string and check if it contains the search string
3 - repeat the steps in a loop
回答by namnt
You can write a function to return array of occurrence positions, Java has String.regionMatches function which is quite handy
您可以编写一个函数来返回出现位置的数组，Java 有 String.regionMatches 函数，非常方便
public static ArrayList<Integer> occurrencesPos(String str, String substr) {
final boolean ignoreCase = true;
int substrLength = substr.length();
int strLength = str.length();
ArrayList<Integer> occurrenceArr = new ArrayList<Integer>();
for(int i = 0; i < strLength - substrLength + 1; i++) {
if(str.regionMatches(ignoreCase, i, substr, 0, substrLength)) {
occurrenceArr.add(i);
}
}
return occurrenceArr;
}
回答by To Kra
I am using: Apache Commons Lang: StringUtils.ordinalIndexOf()
我正在使用： Apache Commons Lang：StringUtils.ordinalIndexOf()
StringUtils.ordinalIndexOf("Java Language", "a", 2)
