I write an app in Android Studio and want to save a bitmap which contains a self-made qr-code. If the code contains a text with less than 20 characters it works but not if the code contains more than 20 chars. The creation works but not the saving. Here’s my code:
https://github.com/GrossadmiralThrawn/MyBarCode.git

import android.graphics.Bitmap
import android.os.Environment
import android.os.StatFs
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.text.SimpleDateFormat
import java.util.Date
import java.util.Locale

class ExportLocal(private var data: Bitmap) : IExport {
override fun setData(newData: Bitmap) {
    data = newData
}

private fun getDataSize(): Long {
    return data.byteCount.toLong()
}

private fun getAvailableInternalMemorySizeSpace(): Long {
    val path = Environment.getDataDirectory()
    val stat = StatFs(path.path)
    val blockSize = stat.blockSizeLong
    val availableBlocks = stat.availableBlocksLong
    return availableBlocks * blockSize
}

/**
 * @return a boolean which says if the source is available. In this case it checks if the phone has enough capacities to store the image.
 */
override fun checkAvailability(): Boolean {
    return getDataSize() < getAvailableInternalMemorySizeSpace()
}

override fun export(information: String?): Boolean {
    val timeStamp: String = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
    val folderName = "MyBarcodeData"
    val fileName = if (!information.isNullOrEmpty()) {
        "${sanitizeFileName(information)}_$timeStamp.jpg"
    } else {
        "barcode_$timeStamp.jpg"
    }
    val folder = File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), folderName)

    if (!folder.exists()) {
        folder.mkdirs()
    }

    val file = File(folder, truncatedFileName(fileName))

    return try {
        FileOutputStream(file).use { out ->
            data.compress(Bitmap.CompressFormat.JPEG, 100, out)
        }
        true
    } catch (e: IOException) {
        e.printStackTrace()
        false
    }
}

private fun truncatedFileName(fileName: String): String {
    return if (fileName.length > 90) {
        fileName.subSequence(0, 89).toString()
    } else {
        fileName
    }
}

private fun sanitizeFileName(fileName: String): String {
    // Replace invalid characters in file name with underscores
    return fileName.replace("[^a-zA-Z0-9.-]".toRegex(), "_")
}

private fun getExternalFilesDir(type: String): File? {
    return Environment.getExternalStoragePublicDirectory(type)
}

}

class ShowCodeActivity : AppCompatActivity() {
private lateinit var returnButton: Button
private lateinit var saveButton: Button
private lateinit var shareButton: Button
private lateinit var receivedIntent: Intent
private lateinit var showCodeImageView: ImageView
private lateinit var saveCode: IExport
private var creationSucceed: Boolean = true

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    enableEdgeToEdge()
    setContentView(R.layout.activity_show_code)
    ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets ->
        val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
        v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
        insets
    }
    receivedIntent = intent
    returnButton = findViewById(R.id.returnToPreviousButton)
    saveButton = findViewById(R.id.saveButton)
    shareButton = findViewById(R.id.shareButton)
    showCodeImageView = findViewById(R.id.showCodeImageView)
    val codeText = receivedIntent.getStringExtra("codeText")

    when (receivedIntent.getStringExtra("codeType")) {
        "QR" -> generateQRCode(codeText!!)
        "Bar" -> generateBarcode(codeText!!)
    }

    saveButton.setOnClickListener {
        val options = arrayOf(getString(R.string.save_location_local))

        AlertDialog.Builder(this)
            .setTitle(getString(R.string.select_save_option))
            .setItems(options) { _, which ->
                when (which) {
                    0 -> saveLocally(showCodeImageView.drawable?.toBitmap(), codeText)
                }
            }
            .setNegativeButton(getString(R.string.quit)) { dialog, _ ->
                dialog.dismiss()
            }
            .show()
    }

    shareButton.setOnClickListener {
        shareImage()
    }

    returnButton.setOnClickListener {
        finish()
    }
}

private fun saveLocally(data: Bitmap?, information: String?) {
    data?.let {
        saveCode = ExportLocal(it)
        val success = saveCode(data, saveCode, information)
        if (success) {
            Toast.makeText(this, getString(R.string.save_successfully), Toast.LENGTH_SHORT).show()
        } else {
            Toast.makeText(this, getString(R.string.save_unsuccessfully), Toast.LENGTH_SHORT).show()
        }
    } ?: Toast.makeText(this, getString(R.string.save_unsuccessfully), Toast.LENGTH_SHORT).show()
}

private fun saveCode(data: Bitmap, storeObject: IExport, information: String?): Boolean {
    val options = arrayOf("Automatic Naming", "Custom Naming")
    var selectedOption = 0

    storeObject.setData(data)

    if (storeObject.checkAvailability()) {
        if (storeObject.export(information)) {
            return true
        }
    }

    return false
}

private fun generateQRCode(data: String) {
    val barcodeEncoder = BarcodeEncoder()
    try {
        val bitmap = barcodeEncoder.encodeBitmap(data, BarcodeFormat.QR_CODE, 600, 400)
        showCodeImageView.setImageBitmap(bitmap)
        creationSucceed = true
    } catch (e: WriterException) {
        e.printStackTrace()
    }
}

private fun generateBarcode(data: String) {
    val barcodeEncoder = BarcodeEncoder()
    try {
        val bitmap = barcodeEncoder.encodeBitmap(data, BarcodeFormat.MAXICODE, 800, 400)
        showCodeImageView.setImageBitmap(bitmap)
        creationSucceed = true
    } catch (e: WriterException) {
        e.printStackTrace()
    }
}

private fun shareImage() {
    val bitmap = showCodeImageView.drawable?.toBitmap()

    if (bitmap != null) {
        try {
            // Save bitmap to cache directory
            val cachePath = File(cacheDir, "images")
            cachePath.mkdirs() // Create directory if not exists
            val file = File(cachePath, "shared_image.png")
            val fileOutputStream = FileOutputStream(file)
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream)
            fileOutputStream.close()

            // Get file URI
            val fileUri: Uri = FileProvider.getUriForFile(
                this,
                "$packageName.fileprovider",
                file
            )

            // Create share intent
            val shareIntent = Intent().apply {
                action = Intent.ACTION_SEND
                putExtra(Intent.EXTRA_STREAM, fileUri)
                type = "image/*"
                addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION) // Grant permission to read the URI
            }

            // Start share activity
            startActivity(Intent.createChooser(shareIntent, getString(R.string.share_via)))
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }
}

}

It tried to improve the qualitiy ofe the code and to cut of to long names and also to play a little bit with the library setting. Also I tried to add some permissions but it didn’t help.
It would be nice if someone could look over the code.