RuntimeException: Unable to create output dir: /storage/emulated/0/app_spoon-screenshots

Understanding the Error

The error “RuntimeException: Unable to create output dir: /storage/emulated/0/app_spoon-screenshots” is a common issue that arises when Android applications try to create a directory for storing screenshots or other files. This error signals that the app lacks the necessary permissions to write to the specified location, typically the external storage (SD Card) on your device.

Causes of the Error

1. Insufficient Permissions:

The primary culprit is inadequate permissions. Android’s security model strictly enforces permission requests for file access, particularly for writing to external storage. If your app hasn’t obtained the required permissions, it won’t be able to create directories or write files.

2. Storage Access Framework (SAF) Restrictions:

The Storage Access Framework (SAF) is a system that allows users to control which apps can access files on their device. If your app is using SAF and the user has restricted access to the specified directory, the error will occur.

3. Directory Access Restrictions:

Certain directories on external storage might be restricted by the device manufacturer or by specific system settings. The app might lack permission to write to these restricted areas.

Resolving the Error

1. Request Storage Permissions:

Ensure your app is requesting necessary permissions from the user. Here’s how you’d typically implement this in Android:

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;

// ... in your activity or relevant class

// Check if permission is granted
if (ContextCompat.checkSelfPermission(this,
        Manifest.permission.WRITE_EXTERNAL_STORAGE)
        != PackageManager.PERMISSION_GRANTED) {
    // Request permission from user
    ActivityCompat.requestPermissions(this,
        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
        1);
} else {
    // Permission already granted, proceed with creating the directory
    createOutputDirectory();
}

// Function to create the output directory
private void createOutputDirectory() {
    // Create directory path
    String directoryPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/app_spoon-screenshots";
    File outputDirectory = new File(directoryPath);
    if (!outputDirectory.exists()) {
        outputDirectory.mkdirs();
    }
}

2. Use Storage Access Framework (SAF):

If your app needs to access files in a specific directory, utilize SAF to let users grant access. SAF provides a user-friendly interface to choose files and folders. Here’s a basic example:

import android.content.Intent;
import android.net.Uri;
import android.support.v4.app.ActivityOptionsCompat;

// ... in your activity or relevant class

// Trigger an intent to choose a directory using SAF
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
startActivityForResult(intent, 1);

// Handle the result in onActivityResult()
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == 1 && resultCode == RESULT_OK) {
        Uri treeUri = data.getData();
        if (treeUri != null) {
            // Use treeUri to access the selected directory
        }
    }
}

3. Explore Alternatives:

• Use internal storage for storing temporary or app-specific files.
• If possible, consider storing files in a cloud storage solution.

Troubleshooting Tips

• Verify your device’s SD card permissions and make sure it’s properly mounted.
• Check for updates to your app or Android operating system.
• Use a file explorer to manually check if the output directory exists and if your app has write access to it.

Conclusion

The “RuntimeException: Unable to create output dir” error usually stems from missing permissions or restrictions on external storage access. By carefully addressing these issues, requesting the right permissions, and adopting best practices for file access, you can ensure your Android app functions correctly and safely.