在 Java 中查找字符串中子字符串的第二个匹配项

int first = string.indexOf("is");
int second = string.indexOf("is", first + 1);

This overload starts looking for the substring from the given index.

Use overloaded version of indexOf(), which takes the starting index (fromIndex) as 2nd parameter:

str.indexOf("is", str.indexOf("is") + 1);

i think a loop can be used.

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

You can write a function to return array of occurrence positions, Java has String.regionMatches function which is quite handy

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;
}

I am using: Apache Commons Lang: StringUtils.ordinalIndexOf()

StringUtils.ordinalIndexOf("Java Language", "a", 2)

if you want to find index for more than 2 occurrence:

public static int ordinalIndexOf(String fullText,String subText,int pos){


if(fullText.contains(subText)){
if(pos <= 1){
return fullText.indexOf(subText);
}else{
--pos;
return fullText.indexOf(subText, ( ordinalIndexOf(fullText,subText,pos) + 1) );
}
}else{
return -1;
}


}

I hope I'm not late to the party.. Here is my answer. I like using Pattern/Matcher because it uses regex which should be more efficient. Yet, I think this answer could be enhanced:

    Matcher matcher = Pattern.compile("is").matcher("I think there is a smarter solution, isn't there?");
int numOfOcurrences = 2;
for(int i = 0; i < numOfOcurrences; i++) matcher.find();
System.out.println("Index: " + matcher.start());

It seems to be a good party... I'm in:

public static int nthIndexOf(String str, String subStr, int count) {
int ind = -1;
while(count > 0) {
ind = str.indexOf(subStr, ind + 1);
if(ind == -1) return -1;
count--;
}
return ind;
}

Anyone who is looking for Nth occurance of string

    public class NthOccuranceExample {
    

public static void main(String[] args) {
String str1 = "helloworld good morning good evening good night";
String str2 = "ing";
int n = 2;
    

int index = nthOccurrence(str1, str2, n);
System.out.println("index of str2 in str1 at occurrence "+ n +" = "+ index);
}
    

public static int nthOccurrence(String str1, String str2, int n) {
    

String tempStr = str1;
int tempIndex = -1;
int finalIndex = 0;
for(int occurrence = 0; occurrence < n ; ++occurrence){
tempIndex = tempStr.indexOf(str2);
if(tempIndex==-1){
finalIndex = 0;
break;
}
tempStr = tempStr.substring(++tempIndex);
finalIndex+=tempIndex;
}
return --finalIndex;
}
}