Permission to write on Android SD card

Question

I have a problem writing to an SD card, here is the code: (Sorry for the code layout, just copy it)

public class SaveAndReadManager { private String result; private String saveFileName = "eventlist_savefile"; public String writeToFile( ArrayList<Event> arrlEvents ){ FileOutputStream fos = null; ObjectOutputStream out = null; try{ File root = Environment.getExternalStorageDirectory(); if( root.canWrite() ){ fos = new FileOutputStream( saveFileName ); out = new ObjectOutputStream( fos ); out.writeObject( arrlEvents ); result = "File written"; out.close(); }else{ result = "file cant write"; } }catch( IOException e ){ e.printStackTrace(); result = "file not written"; } return result; } public boolean readFromFile(){ return false; } } 

I have not implemented readFromFile () yet. The problem is that root.canWrite () returns false all the time. Here is the manifest file:

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".InfoScreen" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> 

  <activity android:name=".EventCalendar" android:label="@string/app_name" /> <activity android:name=".MakeEvent" android:label="@string/app_name" /> <activity android:name=".ViewEvent" android:label="@string/app_name" /> </application> <uses-sdk android:minSdkVersion="8" /> 

I asked for permission to write, and on my avd, if I go to settings → SD card and phone, I will say that I have 1 gb on the SD card for recording. Please, help.

Thanks:)

Answer 1

What result do you see retunred from writeToFile? "file not written" or "file can not write"?

When I ran your code, it fell into an IOException catch block with the result “file not written”. The reason for this was that fos was not defined correctly:

 fos = new FileOutputStream( saveFileName ); 

it should be:

 fos = new FileOutputStream( root + "/" saveFileName ); 

After I changed this line, I got the result "File written" returned from writeToFile.

Answer 2

Try checking the status of the SD card before attempting to record it. It can be used as a shared disk, damaged, full, etc. A list of states can be found here: http://developer.android.com/reference/android/os/Environment.html

Here is an example of getting states:

 String state = Environment.getExternalStorageState(); if (Environment.MEDIA_MOUNTED.equals(state)) { mExternalStorageAvailable = mExternalStorageWriteable = true; } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) { mExternalStorageAvailable = true; mExternalStorageWriteable = false; } else { mExternalStorageAvailable = mExternalStorageWriteable = false; } 

Answer 3

I use the following code to record audio data (successfully) to my Android SD card. My application requires RECORD_AUDIO permission, but nothing else.

 File file = new File (Environment.getExternalStorageDirectory().getAbsolutePath() + FILE_NAME); if (file.exists()) file.delete(); // Delete any previous recording try { file.createNewFile(); // Create the new file } catch (IOException e) { Log.e (TAG, "Failed to create " + file.toString()); } try { OutputStream os = new FileOutputStream (file); BufferedOutputStream bos = new BufferedOutputStream (os, 8000); DataOutputStream dos = new DataOutputStream (bos); // Create a DataOutputStream to write the audio data to the file // Create an AudioRecord object to record the audio int bufferSize = AudioRecord.getMinBufferSize (frequency, channelConfig, Encoding); AudioRecord audioRecord = new AudioRecord (MediaRecorder.AudioSource.MIC, frequency, channelConfig, Encoding, bufferSize); short[] buffer = new short[bufferSize]; // Using "short", because we're using "ENCODING_PCM_16BIT" audioRecord.startRecording(); while (isRecording) { int bufferReadResult = audioRecord.read (buffer, 0, bufferSize); for (int i = 0; i < bufferReadResult; i++) dos.writeShort (buffer[i]); } audioRecord.stop(); dos.close(); } catch (Exception t) { Log.e (TAG, "Recording Failed"); } 

It seems to me that you miss the call to getAbsolutePath () attached to the call to getExternalStorageDirectory () (which may have the same result as Marc Bernstein's hard coded solution).

Answer 4

I also had to include the following link (since where I got the code that is written to the SD card ...):

http://emeadev.blogspot.com/2009/09/raw-audio-manipulation-in-android.html