Find duplicate words java

Scanner sc = new Scanner(System.in);
        int count=0;
        String pass;
        String word = ".";
        String userWords = "";

        do {
            System.out.print("Word: ");
            pass = sc.nextLine();
              String[] sentence = pass.split(" ");
        }
        while (!(pass.equals(word)));
       String  sameWord = " ";
          boolean match = false;
        for (int i = 0; i < sentence.length; i++) {
            if (sentence[i].equals(pass)) {

               sentence[i] += pass + " ";
                match = true;
                sentence = pass.split(" ");
       // String= sentence[i];
                System.out.println("This word already exists!");
                return;
            }
            count++;
            if(count> sentence.length) {
                sentence=Arrays.copyOf(sentence,sentence.length+1);
            }

        }
        for(int j=0; j< sentence.length;j++) {
            System.out.println("All words:");
            System.out.println(sentence[j]);
            System.out.println();
        }