Null Pointer Exception when reading a file

Question

I have two activities: In the first activity I am passing the String "pathName" to a second activity. I am receiving the extra okay and I can create a File from this path name. The problem arises when I try to call .listFiles() from that file.

Code: First Activity

    public void onItemClick(AdapterView<?> parent, View v, int position, long id) {

            String pathToSend = albumDirectory+albumList.get(position);
            Intent i = new Intent(getBaseContext(),GalleryImageSlider.class);
            i.putExtra("pathName", pathToSend);
            startActivity(i);
        }

Second Activity:

    List<File> imageList;

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_capture_gallery);

    Intent i = getIntent();
    filePath = i.getExtras().getString("pathName");
    albumFile = new File(filePath);

    Log.d("Fragment","File Path: " + albumFile.getAbsolutePath());
            //I can see this directory on my tablet, and I can see the files within. So the file
            path is correct

    try{
        imageList = Arrays.asList(albumFile.listFiles());

    }
    catch(NullPointerException e){
        Log.e("Error", "NPE: " + e);
    }

I understand that .listFiles returns null if there are no files to be read. But there are files, and I can see them when I look in my tablets file manager.

Anyone see a way to resolve this? Thanks before hand.

Could you post the stack trace?

user2189871
– user2189871

2013-08-09 11:16:38 +00:00
Commented Aug 9, 2013 at 11:16 — user2189871
– user2189871, Commented Aug 9, 2013 at 11:16

Renan Bandeira · Accepted Answer · 2013-08-09 06:15:01Z

2

Maybe the problem is because the path isn't a directory or you don't have permissions to read it. Here are some tips of methods that you should verify before call listFiles():

file.canRead() - returns a bool that says if the file is readable or not.
file.isDirectory() - returns a bool that says if the file is a directory or not.

Since you said that the path is correct, probably the second option isn't the solution, but the first one can be.

answered Aug 9, 2013 at 6:15

Renan Bandeira

3,26819 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

David Kooi Over a year ago

Ended up referencing the file in a different way which worked. But I'll mark you correct since I am going to add these methods for error checking. Thanks

user2652394 · Accepted Answer · 2013-08-09 05:48:54Z

0

You could be possibly missing the PERMISSON to do so, listFiles() return null is some cases such the directory can not be found or you dont have permission to access to that directory. Check your PERMISSION in AndroidManifest.xml. Have you add the READ_EXTERNAL_STORAGE for the permission? Hope this helps.

answered Aug 9, 2013 at 5:48

user2652394

1,6961 gold badge13 silver badges15 bronze badges

Comments

Kirill Ryabin · Accepted Answer · 2013-08-09 12:43:29Z

0

When you connect your device to PC sd card is removed and you can't access files.

answered Aug 9, 2013 at 12:43

Kirill Ryabin

1931 gold badge2 silver badges15 bronze badges

Collectives™ on Stack Overflow

Null Pointer Exception when reading a file

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related