Getting list of images from a folder in android kotlin

Question

I'm trying to get list of images from a folder using this function

var gpath:String = Environment.getExternalStorageDirectory().absolutePath
var spath = "testfolder"
var fullpath = File(gpath + File.separator + spath)
var list = imageReader(fullpath)

fun imageReader(root : File):ArrayList<File>{
    val a : ArrayList<File> ? = null
    val files = root.listFiles()
    for (i in 0..files.size){
        if (files[i].name.endsWith(".jpg")){
            a?.add(files[i])
        }
    }
    return a!!
}

but i have these exceptions :

java.lang.ArrayIndexOutOfBoundsException:length=3;index=3

kotin.kotlinNullPointerException

I've read about this problem but i have no idea how to fix it,

any help please?

Since the indexing of the `Array` is zero-based, the last element would be `files.size - 1`. — earthw0rmjim, Jul 04 '18 at 07:55
thanks, it fixed the first exception, but NullPointerException still there, any idea ? — evals, Jul 04 '18 at 08:03
@evals Please provide full *logcat* error and code where you trying to call function. — Jay Rathod, Jul 04 '18 at 08:08
@evals It seems looking you need to pass *fullpath* instead of *path* in *var list = imageReader(path)* check my answer for same and apply. — Jay Rathod, Jul 04 '18 at 08:14

Jay Rathod · Accepted Answer · 2018-07-04T08:39:10.957

For Null Pointer you may need to change and pass fullpath instead of path inside var list = imageReader(path).

Wrong

var fullpath = File(gpath + File.separator + spath)
var list = imageReader(path)

Right

var gpath:String = Environment.getExternalStorageDirectory().absolutePath
var spath = "testfolder"
var fullpath = File(gpath + File.separator + spath)
var list = imageReader(fullpath)

EDIT 1

I have made few changes to function and apply it inside override fun onCreate as below.

var gpath: String = Environment.getExternalStorageDirectory().absolutePath
var spath = "Download"
var fullpath = File(gpath + File.separator + spath)
Log.w("fullpath", "" + fullpath)
imageReaderNew(fullpath)

Function

fun imageReaderNew(root: File) {
    val fileList: ArrayList<File> = ArrayList()
    val listAllFiles = root.listFiles()

    if (listAllFiles != null && listAllFiles.size > 0) {
        for (currentFile in listAllFiles) {
            if (currentFile.name.endsWith(".jpeg")) {
                // File absolute path
                Log.e("downloadFilePath", currentFile.getAbsolutePath())
                // File Name
                Log.e("downloadFileName", currentFile.getName())
                fileList.add(currentFile.absoluteFile)
            }
        }
        Log.w("fileList", "" + fileList.size)
    }
}

Logcat Output

W/fullpath: /storage/emulated/0/Download
E/downloadFilePath: /storage/emulated/0/Download/download.jpeg
E/downloadFileName: download.jpeg
E/downloadFilePath: /storage/emulated/0/Download/images.jpeg
E/downloadFileName: images.jpeg
E/downloadFilePath: /storage/emulated/0/Download/images (1).jpeg
E/downloadFileName: images (1).jpeg

sorry my wrong , i edited the question, but this is not the problem, using debugging mode and BreakPoints i see the the function return (a) as null — evals, Jul 04 '18 at 08:19
and im 100% certain there are .jpg files in the provided path — evals, Jul 04 '18 at 08:21
@evals Check my updated answer made few changes in function and improved this will solve you all issues. Made it easy. — Jay Rathod, Jul 04 '18 at 08:39
@evals Glad to help you !! Also Upvote the answer so it will be helpful to future visitors. :) — Jay Rathod, Jul 04 '18 at 10:07

score 5 · Answer 2 · answered Jul 04 '18 at 07:55

5

fun imageReader(root : File):ArrayList<File>{
    val a : ArrayList<File> ? = null
    val files = root.listFiles()
    for (i in 0..files.size-1){
        if (files[i].name.endsWith(".jpg")){
            a?.add(files[i])
        }
    }
    return a!!
}

answered Jul 04 '18 at 07:55

Ankita

1,129
1
8
15

greatly fixed the first exception but NullPointerException still there, any idea? – evals Jul 04 '18 at 08:07

score 0 · Answer 3 · edited Jan 06 '20 at 19:49

The above answer is right but it declares a as null and then in loop uses null save. Therefore it detects images but does not add them to the list and the list returns null.

fun imageReader(root: File): ArrayList < File > {
  val a: ArrayList < File > = ArrayList()
  if (root.exists()) {
    val files = root.listFiles()
    if (files.isNotEmpty()) {
      for (i in 0..files.size - 1) {
        if (files[i].name.endsWith(".jpg")) {
          a.add(files[i])
        }
      }
    }
  }
  return a!!
}

score 0 · Answer 4 · answered Feb 17 '23 at 09:38

By using MediaStore we can achieve count of image inside a folder and we will add one more check to prevent getting image of subfolders of current folder.

 fun getImageCountInDirectory(context: Context, directoryPath: String): Int {
    var imageCount = 0

    val uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI
    val sortOrder = MediaStore.Images.Media.DATE_MODIFIED + " DESC"
    val selection = "${MediaStore.Images.Media.DATA} like ? and ${MediaStore.Images.Media.DATA} not like ?"
    val selectionArgs = arrayOf("$directoryPath/%", "$directoryPath/%/%") // use % as a wildcard character to select all files inside the directory, and exclude subdirectories

    val cursor = context.contentResolver.query(
        uri,
        null,
        selection,
        selectionArgs,
        sortOrder
    )
    if (cursor != null) {
        imageCount = cursor.count
        cursor.close()
    }

    return imageCount
}

This function will return an integer value and it is the total number of image files inside the folder. And we are using the not like operator and adding %/% to the selectionArgs array to select all files whose path doesn't contain a subdirectory.

Getting list of images from a folder in android kotlin

4 Answers4