file.listFiles() listing and sorting files

Programming Questions

andrew.e...

file.listFiles() listing and sorting files

in Programming Questions • 1 years ago

I am trying to list the contents in a directory in the order of creation.

like you get by using ls -t1r

I found this in the learning section.

DirectoryList \ Learning \ Processing.org

Exerpt:

// This function returns all the files in a directory as an array of File objects

// This is useful if you want more info about the file

File[] listFiles(String dir) {

File file = new File(dir);

if (file.isDirectory()) {

File[] files = file.listFiles();

return files;

} else {

// If it's not a directory

return null;

}

Any clues how to implement file.listFiles() to list files in creation in order?

Thank you,

AndrewT

Replies(1)

jbum

Re: file.listFiles() listing and sorting files

1 years ago

We have strayed from Processing to pure Java, but this shows the basic method. Google for "Java sort comparator" for information about how to sort.

One big problem: Native java only supports reading modification dates, not creation dates, because creation dates are not supported across all platforms. I used modification date, but you may be able to find a platform-specific way of obtaining creation date.

import java.io.File;
import java.util.Comparator;
import java.text.SimpleDateFormat; // only needed for display
File[] listFiles(String dir)
{
File file = new File(dir);
if (file.isDirectory()) {
File[] files = file.listFiles();
return files;
} else {
// If it's not a directory
return null;
}
}
class ModificationDateCompare implements Comparator<File> {
public int compare(File f1, File f2) {
return Long.valueOf(f1.lastModified()).compareTo(f2.lastModified());
}
}
void setup()
{
size(500,500);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MMM/dd hh:mm:ss z"); // used only for display
File [] fl = listFiles("/");
Comparator<File> byModificationDate = new ModificationDateCompare();
Arrays.sort(fl, byModificationDate);
// print out the results, and show the dates
for (int i = 0; i < fl.length; ++i) {
Date dt = new Date(fl[i].lastModified());
println(sdf.format(dt) + " " + fl[i].toString());
}
exit();
}
void draw()
{
}

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