If you already have complete mobile number in a specific format e.g. +91-99xxxxxxxx and want to fetch country code = IN, then here is a reference to a solution.
Use a lib in your gradle.
//Phone Utils lib.
implementation 'com.googlecode.libphonenumber:libphonenumber:7.0'
And the code which will help to find the country code and other information is as below.
PhoneNumberUtil utils = PhoneNumberUtil.getInstance();
try {
    for (String region : utils.getSupportedRegions()) {
        // Check whether it's a valid number.
        boolean isValid = utils.isPossibleNumber(mobileNo, region);
        if (isValid) {
            Phonenumber.PhoneNumber number = util.parse(mobileNo, region);
            // Check whether it's a valid number for the given region.
            isValid = utils.isValidNumberForRegion(number, region);
            if (isValid) {
                Log.d("Region:" , region); // IN
                Log.d("Phone Code", number.getCountryCode()); // 91
                Log.d("Phone No.", number.getNationalNumber()); // 99xxxxxxxxxx  
            }
        }
    }
} catch (NumberParseException e) {
    e.printStackTrace();
}