I keep trying to run my program to see if I got the code to run as the solution demands but I keep running into a point where I can enter in blank space and the while loop doesn't terminate and main doesn't move on. What's especially baffling is that I haven't touched main. 
package com.codegym.task.task09.task0930;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;

/*
Task about algorithms

*/

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<String> list = new ArrayList<String>();
        while (true) {
            String s = reader.readLine();
            if (s.isEmpty()) break;
            list.add(s);
        }

        String[] array = list.toArray(new String[list.size()]);
        sort(array);

        for (String x : array) {
            System.out.println(x);
        }
    }

    public static void sort(String[] array) {
        // write your code here
        ArrayList<String> words = new ArrayList<>();
        ArrayList<Integer> numbers = new ArrayList<>();

        for (String S:array)
        {
            if (isNumber(S)){
                numbers.add((Integer.parseInt(S)));
            }
            else {
                words.add(S);
            }
        }


        Collections.sort(numbers);
        Collections.reverse(numbers);

        for (int i = 0; i < words.size() - 1; i++) {
            if (!isGreaterThan(words.get(i), words.get(i + 1))) {
                String temp = words.get(i + 1);
                words.set(i + 1, words.get(i));
                words.set(i, temp);
            }

            i = 0;
        }

        //Collections.reverse(words);
        int x = 0;
        int y = 0;
        for( int i = 0 ; i < array.length; i++){
            if (isNumber(array[i])){
                array[i] =String.valueOf(numbers.get(x));
                x++;
            }
            else {
                array[i]=words.get(y);
                y++;
            }

        }
    }

    // String comparison method: 'a' is greater than 'b'
    public static boolean isGreaterThan(String a, String b) {
        return a.compareTo(b) > 0;
    }


    // Is the passed string a number?
    public static boolean isNumber(String s) {
        if (s.length() == 0) return false;

        char[] chars = s.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            char c = chars[i];
            if ((i != 0 && c == '-') // The string contains a hyphen
                    || (!Character.isDigit(c) && c != '-') // or is not a number and doesn't start with a hyphen
                    || (i == 0 && c == '-' && chars.length == 1)) // or is a single hyphen
            {
                return false;
            }
        }
        return true;
    }
}