Find all occurrences of substring in string in Java

Question

I\'m trying to find all occurrences of a substring in a string in Java.

For example: searching \"ababsdfasdfhelloasdf\" for \"asdf\" would return [8,17] since there

Answer 1

Using a regex is definitely an overly heavy solution for finding substrings, and it'll especially be a problem if your substring contains special regex characters like .. Here's a solution adapted from this answer:

String str = "helloslkhellodjladfjhello";
String findStr = "hello";
int lastIndex = 0;
List result = new ArrayList();

while(lastIndex != -1) {

    lastIndex = str.indexOf(findStr,lastIndex);

    if(lastIndex != -1){
        result.add(lastIndex);
        lastIndex += 1;
    }
}