public void getAllSub(String str) { Set<String> result = new HashSet<String>(); int length = str.length(); int maxlength = length/2; for (int i = 1; i <= maxlength; i++) { for (int j = 0; j+i < length; j++) { String target = str.substring(j, j+i); String after = str.replaceAll(target, ""); if(length > (after.length()+target.length())){ result.add(target); } } } for (String string : result) { System.out.println(string); } }