String symbols = "abcdefghijklmnopqrstuvwxyz";

    char[] array = symbols.toCharArray();
    ArrayList<String> arrayList = new ArrayList<>();
    for (int i = 0; i < array.length; i++) {
        arrayList.add(i, String.valueOf(array[i]));
    }
    Collections.shuffle(arrayList);
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < arrayList.size(); i++) {
        sb.append(arrayList.get(i));
    }
    Log.i("log__", "sb.toString() - " + sb.toString());

I/log__: sb.toString() - jldcgsxkhnfmaqbzuprevwoyti
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