How to Custom Sort File Names stored in List<String> using JAVA

Question

I have File Names like :

1. 20150316_Chiru.sql
2. 20150316_Chiru_Derby.sql
3. 20150316_Chiru_Oracle.sql
4. 20150317_Deepak.sql
5. 20150317_Deepak_Derby.sql
6. 20150317_Deepak_Oracle.sql
7. 20150318_Momalisa.sql
8. 20150318_Momalisa_derby.sql
9. 20150318_Momalisa_oracle.sql

and I want to sort it like :

1. 20150316_Chiru_Derby.sql
2. 20150316_Chiru_Oracle.sql
3. 20150316_Chiru.sql
4. 20150317_Deepak_Derby.sql
5. 20150317_Deepak_Oracle.sql
6. 20150317_Deepak.sql
7. 20150318_Momalisa_derby.sql
8. 20150318_Momalisa_oracle.sql
9. 20150318_Momalisa.sql

Please help Me With some Ideas or codes

Answer 1

One of the solutions is to use sort(List list, Comparator c)

See Collections.sort() using comparator? topic.

And code can look like:

public void sortFiles(BufferedReader fileReader) {
    List<String> fileList = new ArrayList<String>();
    String str;
    try {
        while ((str = fileReader.readLine()) != null) {
            fileList.add(str);
        }
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    Collections.sort(fileList, new ThisIsMyThing());
    System.out.println("Sorted AS");
    Iterator<String> fileNameIterator = fileList.iterator();
    while (fileNameIterator.hasNext()) {
        System.out.println(fileNameIterator.next());
    }
}

class ThisIsMyThing implements Comparator<Object> {
    public int compare(Object o1, Object o2) {

        String s1 = (String) o1;
        String s2 = (String) o2;

        String[] l_side = s1.split("_");
        String[] r_side = s2.split("_");

        //Check if numbers are equal
        if (l_side[0].equals(r_side[0])) {
            if (l_side.length == r_side.length) {
                return s1.compareTo(s2);
            } else {
                return l_side.length > r_side.length ? -1 : 1;
            }
        } else {
            return s1.compareTo(s2);
        }
    }
}