List files from internal memory in the ListView

Thinking a little bit, you can make multiple internal and external device listings in one application using Environment and Context .

• Environment.getRootDirectory() : Returns the root directory of the Android system.
• Environment.getExternalStorageDirectory() : Return shared main / external storage directory.
• Environment.getDataDirectory() : Return the user data directory.
• Environment.getDownloadCacheDirectory() : Return the download / cache content directory.
• getFilesDir() : returns a path that is linked to your package and context is required to access the package name.

First, as an example, you need to give your directories permission to manifest.xml if you want to do a listing of external files using READ_EXTERNAL_STORAGE . If by chance you use getRootDirectory() this permission is not required. And if you're using Android API 6.0 + , you'll have to read a little more about Requesting Permissions at Run Time .

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

In your main.xml , you will enter your ListView so that all files are listed:

<ListView
        android:id="@+id/list"
        android:layout_height="wrap_content"
        android:layout_width="match_parent">
</ListView>

And finally in your class Main is going to do this:

    ListView listView ;
    ArrayList<String> list = new ArrayList<String>();
    listView = (ListView) findViewById(R.id.list);

    String path = Environment.getRootDirectory().toString();
    Log.d("Files", "Path: " + path);
    File directory = new File(path);
    File[] files = directory.listFiles();
    Log.d("Files", "Size: "+ files.length);
    for (int i = 0; i < files.length; i++)
    {
        list.add(files[i].getName());
    }

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1, list);
    // Assign adapter to ListView
    listView.setAdapter(adapter);

If you want to list other directories in a specific folder, just put the folder name in your path :

String path = Environment.getRootDirectory().toString()+"/"+diretorioEspecifico;