public static String getPartOfString(String string) throws TooShortStringException{ String s2=""; if(string != null || string.indexOf('\t') != -1 || string.indexOf('\t', (string.indexOf('\t')+1)) != -1 ){ s2 = string.substring((string.indexOf('\t')+1), (string.indexOf('\t', (string.indexOf('\t')+1)))); }else{ throw new TooShortStringException(); } return s2; } а надо было именно так: if(string == null || string.indexOf('\t') == -1 || string.indexOf('\t', (string.indexOf('\t')+1)) == -1 ){ throw new TooShortStringException();