String：求str1包含str2的个数

int count = 0;
public int getCount(String subStr,String mainStr){
    if(mainStr.length() >= subStr.length()&&mainStr.contains(subStr)){
        for (int i = 0; i < mainStr.length(); i++) {
            if(mainStr.substring(i).indexOf(subStr) == 0){
                count++;
            }
        }
        return count;
    }
    return count;
}