How to know if a given string is substring from another string in Java

Question

Hi I have to compute if a given string is substring of a bigger string. For example

String str = \"Hallo my world\";
String substr = \"my\"

<

Answer 1

    public boolean isSubString(String smallStr, String largerStr) {
    char[] larger = largerStr.toCharArray();
    char[] smaller = smallStr.toCharArray();

    int i = 0;

    for (int j = 0; j < larger.length; j++) {
        if(larger[j] == smaller[i]){
            if(i == smaller.length -1){
                //done we found that this string is substring
                return true;
            }
            i++;
            continue;
        }else{
            if(i > 0){
                //that means we encountered a duplicate character before and if string was substring 
                // it shouldn't have hit this condition..
                if(larger.length - j >= smaller.length){
                    i = 0;
                    //reset i here because there are still more characters to check for substring..
                }else{
                    //we don't have enough characters to check for substring.. so done..
                    return false;
                }

            }
        }

    }

    return false;
}