java sorting arraylist collections java-8

Java List String sort Based on Integer with multiple underscore's

Hi All I have arrayList of String datatype but needs to sort like integer with multiple underscore's using Java 8 only ,For your reference I have added sample data, the original data came Liferay 7.1 DDL

List<String> keyValues = new ArrayList<String>();
keyValues.add("100_10_20_1");
keyValues.add("100001");
keyValues.add("100002");
keyValues.add("100002_1");
keyValues.add("100003");
keyValues.add("100");
keyValues.add("100_1");
keyValues.add("100_2");
keyValues.add("100_1_1");
keyValues.add("100_10_20");
keyValues.add("10000001");
keyValues.add("100_10_20_2");

i tried to replace the underscore with 0 but what happens sometimes 100_1 replace _ with 0 then it becomes 10001 but what if i already have 10001 value present in list ? even same thing for empty if i replace _ with "" then it becomes 1001 but what if i already have 1001 then again i am facing issue

Exact logic based on underscore was

 100
 100_1
 100_1_2 
 /after that only/
 100_2
 100_2_2
/after that/
 103
 104
 105
 10000
/similarly the pattern repeats/
 10000_1
 10000_2
 10000_2_1
 100002

i need the exact output as

    100
    100_1
    100_1_1
    100_2
    100_10_20
    100_10_20_1
    100_10_20_2
    100001
    100002
    100002_1
    100003
    10000001

i tried with replacing underscore with 0 or empty space but there is possiblity of if it had already that number present in list,if i replace with dot and storing as Double then multiple pointer exception will occur

Solution

I made a comparator then split the string and process based on the min amount of tokens each string has.

static Comparator<String> stringComparator = new Comparator<String>() {
        @Override
        public int compare(String o1, String o2) {
            String[] s1 = o1.split("_");
            String[] s2 = o2.split("_");

            int minLen = Math.min(s1.length, s2.length);

            for (int i=0; i < minLen; i++){
                if (!s1[i].equals(s2[i])){
                    return Integer.parseInt(s1[i]) - Integer.parseInt(s2[i]);
//                    return s1[i].compareTo(s2[i]);  //not natural order/sort
                }
            }

            return o1.compareTo(o2);
        }
    };

Calling it like so:

    List<String> keyValues = new ArrayList<String>();
    keyValues.add("100001");
    keyValues.add("100002");
    keyValues.add("100002_1");
    keyValues.add("100003");
    keyValues.add("100");
    keyValues.add("100_1");
    keyValues.add("100_2");
    keyValues.add("100_1_1");
    keyValues.add("100_10_20");
    keyValues.add("10000001");
    keyValues.stream().sorted(stringComparator).forEach(System.out::println);

Gives output: