SpamMatcher.java

private static final Pattern multipleChars = Pattern.compile("([a-zA-Z]+)(\1{2,})");

public static String cleanSpam(String spam){
	
	Matcher matcher  = multipleChars.matcher(spam);
	
	if(!matcher.find())
		return spam;
	
	Set<String> chars = new HashSet<>();
	
	do{
		
		chars.add(matcher.group(1));
		
	}while(matcher.find());
	
	for(String s : chars){
		
		spam = spam.replaceAll("(" + s + "){3,}" , s + s);
		
	}
	
	return spam;
}