[Solved] Why does my sorting method for Bigdecimal numbers fails to sort?

Well, since you want to use String numbers, you will have to wrap them in quotations, but your sorting can be much more readable. I would suggest the following

    String[] numbers ={"-100", "50", "0", "56.6", "90", "0.12", ".12", "02.34", "000.000"};
    List<BigDecimal> decimalList = new ArrayList<>();
    for(String s: numbers){
        decimalList.add(new BigDecimal(s));
    }
    Collections.sort(decimalList);
    Collections.reverse(decimalList);     // edit , forgot this line
    decimalList.forEach(System.out::println);