Scanner in = new Scanner(System.in); String[] strings = new String[6]; for (int i = 0; i < strings.length; i++) { strings[i]=in.nextLine(); } String currentString = ""; for (int i=0; i< 6 ;i++) { currentString = strings[i]; for (int y=i+1; y< 6 ;y++) { if (currentString.equals(strings[y])) { strings[i] = "null"; } } } for (int i=0; i< 6 ;i++) { System.out.print(strings[i]+","); }