Calculate fractions of positive, negative and zeros
Using the predicates in your case could be expensive for big list since you use 3 meaning 3 complete iteration on the list.

Here is a small update of you code (I can't use the Java 8 API since I only have the Java 6 at the office ...) to do the same check but without predicate (or if else)

    Scanner scan = new Scanner(System.in);
    int size = scan.nextInt();
    scan.nextLine();

    int[] sum = new int[3];

    String s = scan.nextLine();
    String[] array = s.split(" ");

    double total = array.length;
    for(String d : array ){ //Here, you shoud use your list instead of my array
        sum[Double.compare(Double.parseDouble(d), 0) + 1]++; 
        //compare will return -1 | 0 | 1, adding one to increment the correct cell in the array.
    }

    DecimalFormat df = new DecimalFormat("#.000000");
    System.out.println(df.format(sum[2]/total));
    System.out.println(df.format(sum[0]/total));
    System.out.println(df.format(sum[1]/total));


PS : I could update the code to match your List but to prevent any typo, I prefer to show you the logic I used with the API I can use.