using regex in java

gistfile1.java

private boolean containsNumbers(String s) {
	Pattern p = Pattern.compile(".*\\d.*");
	return p.matcher(s).find();
}
	
private boolean containsCharacters(String s){
	Pattern p = Pattern.compile("[a-zA-Z]");
	return p.matcher(s).find();
}

private boolean containsOneAt(String s){
	int counter = 0;
	Pattern p = Pattern.compile("[@]");
	Matcher m = p.matcher(s);
	while(m.find()){
		counter++;
	}
	return counter == 1;
}