Using contentResolver out of Mainactivity creates Null pointer exception getApplicationContext() on a null object reference

Question

I'm trying to ContentResolver outside Mainactivity . Is there a way to access without null pointer exception

ImageFragment.kt extends Appcompatactivity()


Val uri=contentResolver.insert(MediaStore.images.Media.EXTERNAL_CONTENT_URI,value)

Edit

This line works perfectly inside Mainactivity. I there a way to access outside main class correctly  or it should be only inside Mainactivity

class ImageFragment(context:Context) :AppCompatActivity() {
    var isImageSaved: Boolean = true
    var rot=0
    val mainContext = context // updated code
    var lensFacing=CameraSelector.LENS_FACING_BACK
    fun savingImg(img: Image) {
        val ios: OutputStream?
        val bit: Bitmap?
        var rotBit: Bitmap?
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
            val value = ContentValues()
            val filename =
                SimpleDateFormat(
                    FILENAME_FORMAT,
                    Locale.US
                ).format(System.currentTimeMillis()) + ".jpg"
            value.put(MediaStore.Images.Media.TITLE, filename)
            value.put(MediaStore.Images.Media.DISPLAY_NAME, filename)
            value.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")
            value.put(
                MediaStore.Images.Media.RELATIVE_PATH,
                Environment.DIRECTORY_DCIM + "/" + "Camcorder"
            )
            val uri = mainContext.contentResolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, value)!! //  Updated with main context
            ios =mainContext.contentResolver.openOutputStream(uri)!!
            bit = img.toBitmap()
            setThumbnail(uri)
}
    ios.close()
        img.close()
        isImageSaved = true
}
private fun Image.toBitmap():Bitmap{
        val yBuffer=planes[0].buffer
        val ySize=ByteArray(yBuffer.remaining())
        yBuffer.get(ySize)
        return BitmapFactory.decodeByteArray(ySize,0,ySize.size,null)

    }
    private fun setThumbnail(uri: Uri) {
        gallery.post {
            gallery.setPadding(4)
            gallery.load(uri) {
                crossfade(true)
                transformations(CircleCropTransformation())
            }
        }
    }
    private fun rotateBitmap(Bit: Bitmap, angle: Int): Bitmap {
        val newMat = Matrix()
        if (lensFacing == CameraSelector.LENS_FACING_FRONT) {
            newMat.preScale(1F, -1F)
        }
        newMat.postRotate(angle.toFloat())
        return Bitmap.createBitmap(Bit, 0, 0, Bit.width, Bit.height, newMat, true)

    }
}

MainActivity.kt

val obj=ImageFragment(this)

I tried passing Main context to this class but doesn't works I don't know why this happens as idle shows me the content resolver which has no scope .

Thank you

"This line works perfectly inside Mainactivity" -- that does not appear to be valid Kotlin syntax (`val` needs to be lowercase). Even with that fixed, this line will not be valid anywhere within an activity. I recommend that you post the entire `ImageFragment` class, so we can see exactly where you have this code. — CommonsWare, Sep 07 '20 at 17:54
You can access `contentResolver` as long as you have `Context` reference. You can easily pass `context` reference to plain java class and work your logic. — Hussain, Sep 07 '20 at 18:33
I tried using Mainactivity reference but same exception . Added imagefragment in op — Ajith Selvan, Sep 07 '20 at 19:16

score 1 · Answer 1 · answered Sep 07 '20 at 20:25

1

use MainActivity "context" to access the contentResolver in another class.

if you are using adapter class then

context.getContentResolver();

and fragment

getActivity.getContentResolver();

answered Sep 07 '20 at 20:25

Muhammad Asad

694
6
10

I treid using main activity context in this class but same exception. Updated code under edit – Ajith Selvan Sep 08 '20 at 04:35

Using contentResolver out of Mainactivity creates Null pointer exception getApplicationContext() on a null object reference

1 Answers1