// Check for id is valid format like "ABC1234".
String alphaLen = getResources().getString(R.string.rokaIdAlphaLen);
String numLen = getResources().getString(R.string.rokaIdNumericLen);

if (rokaId.length() > 0 && !Validate.validateRokaId(rokaId, alphaLen, numLen)) {
    etRokaid.setError(getString(R.string.error_incorrect_format));
    focusView = etRokaid;
    cancel = true;
}

public static boolean validateRokaId(String params, String alphaLen, String numLen) {

boolean success = false;
int alphaLength = 0;
int numericLength = 0;

alphaLength = Integer.parseInt(alphaLen.trim());
numericLength = Integer.parseInt(numLen.trim());

if (params.length() == alphaLength + numericLength) {
    if (params.substring(0, alphaLength).matches("[a-zA-Z]*")) {
        if (params.substring(alphaLength, alphaLength+numericLength).matches("[0-9]*")) {
            success = true;
        } else {
            success = false;
        }
    } else {
        success = false;
    }
} else {
    success = false;
}



return success;

}