How to Create a Folder in Android External Storage Programmatically?

How can I programmatically create a folder in the external storage of my Android device?

import java.io.File;  
import android.os.Environment;  

public void createFolder() {  
    File folder = new File(Environment.getExternalStorageDirectory() + "/TollCulator");  
    boolean success = true;  
    if (!folder.exists()) {  
        success = folder.mkdir();  
    }  
    if (success) {  
        // Successfully created directory  
    } else {  
        // Failed to create directory  
    }  
}

Creating a folder in the external storage of an Android device involves using the `File` class and ensuring you have the right permissions in your manifest file. This answer will walk you through the steps, identify common issues, and provide solutions to resolve folder creation failures.

// Example function to create a folder in external storage  
import android.os.Environment;  
import android.util.Log;  
  
public void createFolder() {  
    File folder = new File(Environment.getExternalStorageDirectory(), "TollCulator");  
    boolean success;  
    if (!folder.exists()) {  
        success = folder.mkdirs(); // Use mkdirs() to create any necessary parent directories  
        if (success) {  
            Log.d("Folder Creation", "Directory Created");  
        } else {  
            Log.e("Folder Creation", "Failed to create directory");  
        }  
    } else {  
        Log.d("Folder Creation", "Directory already exists");  
    }  
}

Causes

• The application does not have the necessary storage permissions.
• The device's external storage is not available or is mounted as read-only.
• The path specified for the folder is incorrect or not accessible.

Solutions

• Ensure your app requests runtime permissions for storage if targeting Android 6.0 (API level 23) or higher.
• Verify that external storage is available using `Environment.getExternalStorageState()`.
• Check that the directory path is correct and has the appropriate accessibility.

Mistake: Not requesting runtime permissions on Android 6.0 and higher

Solution: Implement permission checks and request the necessary permissions at runtime.

Mistake: Using `mkdir()` instead of `mkdirs()` which may not create parent directories

Solution: Always use `mkdirs()` to ensure that all needed directories are created.

Mistake: Not checking the external storage state before attempting to create a directory

Solution: Always check the state of the external storage using `Environment.getExternalStorageState()` before accessing it.