CODEWITHSUNDEEP
java
user1253847
user1253847

Reputation: 5451

java : Sort Files based on Creation Date

I am trying to read the latest 10 files based on their creation date .

I tried with this code , but it isn't working , i mean , it doesn't show the new file names in the output when ever i add new files .

import java.io.File;
import java.util.Arrays;
import java.util.Comparator;

public class Main {
    public static void main(String[] args) {
        File inboxDir = new File("D:\\SPOTO");
        File[] files = inboxDir.listFiles();
        Arrays.sort( files, new Comparator()
        {
        public int compare(Object o1, Object o2) {
        return new Long(((File)o1).lastModified()).compareTo(new Long(((File) o2).lastModified()));
        }

        });


        for(int i=0;i<10;i++)
        {
            System.out.println(files[i].getName());
        }


    }
}

I even tried with apache commons io , but that isn't working either ( Means doesn't show new files when new files are created in that directory )

This is my Apache commons io version 

import org.apache.commons.io.comparator.LastModifiedFileComparator;

import java.io.File;
import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        File dir = new File("c:\\");
        File[] files = dir.listFiles();

        Arrays.sort(files, LastModifiedFileComparator.LASTMODIFIED_COMPARATOR);
        for (int i = 0; i < files.length; i++) {
            File file = files[i];
            System.out.printf("File %s - %2$tm %2$te,%2$tY%n= ", file.getName(),
                    file.lastModified());
        }

        Arrays.sort(files, LastModifiedFileComparator.LASTMODIFIED_REVERSE);
        for (int i = 0; i < files.length; i++) {
            File file = files[i];
            System.out.printf("File %s - %2$tm %2$te,%2$tY%n= ", file.getName(),
                    file.lastModified());
        }
    }
}

Upvotes: 2

Views: 10848

Answers (2)

JavaKungFu
JavaKungFu

Reputation: 1314

Try flipping the comparison order:

return new Long(((File)o2).lastModified()).compareTo(new Long(((File) o1).lastModified()));

This works for me testing locally just now.

Upvotes: 3

Alex Gitelman
Alex Gitelman

Reputation: 24722

At least in regular Java version you compare files in the wrong (ascending) order. I multiplied result by -1 and I am seeing latest files first:

return -1* (new Long(((File)o1).lastModified()).compareTo(new Long(((File) o2).lastModified())));

With timestamps the larger one corresponds to the newer file.

Upvotes: 2

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