I have created a file and I want to write in bytes in this file but it's not working. Where is the problem?
public void writeFileExternalStorage() {
File file = new File(getExternalFilesDir(null), "hhh.txt");
try {
if(!file.exists())
file.createNewFile();
FileOutputStream outputStream ;
outputStream = new FileOutputStream(file, true);
outputStream.write(files.getBytes());
outputStream.flush();
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
The createNewFile call will return true if it has successfully created the file. You should check the result of the call, and log an error if it is false.
According to the documentation for getExternalFilesDir (javadoc):
[it m]ay return null if shared storage is not currently available.
If that happens you will call new File(null, "hhh.txt"). That is equivalent to new File("hhh.txt") (javadoc), so the file would be created in the app's "current user directory".
Related
I write a file in internal memory:
byte[] data = ... // (A buffer containing wav data)
String filename = context.getFilesDir().getAbsolutePath() + "/newout.wav";
File file = new File(filename);
FileOutputStream fos = new FileOutputStream(file);
fos.write(data);
fos.close();
Then I try to play it:
MediaPlayer player = new MediaPlayer();
player.setDataSource(filename);
player.prepare();
player.setLooping(false);
player.start();
But the prepare() fails:
java.io.IOException: Prepare failed.: status=0x1
I checked the file and saw that it's permission is -rw-------. I changed it to -rw-r--r--, after that it was being played successfully.
So how come my app can write a file, but can't read it? And how can I make the FileOutputStream to set the permissions right?
To change programaticaly the file permissions to -rw-r--r-- you need to do smoething like this:
Process process = null;
DataOutputStream dataOutputStream = null;
try {
process = Runtime.getRuntime().exec("su");
dataOutputStream = new DataOutputStream(process.getOutputStream());
dataOutputStream.writeBytes("chmod 644 FilePath\n");
dataOutputStream.writeBytes("exit\n");
dataOutputStream.flush();
process.waitFor();
} catch (Exception e) {
return false;
} finally {
try {
if (dataOutputStream != null) {
dataOutputStream.close();
}
process.destroy();
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
If you open a file, the default mode is Context.MODE_PRIVATE, e.g. as in
File file = new File(context.getFilesDir(), filename);
String filename = "myfile";
String string = "Hello world!";
FileOutputStream outputStream;
try {
outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
outputStream.write(string.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
(taken from the documentation). Modes MODE_WORLD_READABLE and MODE_WORLD_WRITABLE are deprecated and do not work on newer devices. So I'd say you should rather write on the external storage to make contents available to other apps.
Note: as per documentation:
External storage:
"It's world-readable, so files saved here may be read outside of your control."
I'm trying to write to an output file on my HTC One and get the following message in the LogCat:
11-21 08:05:18.228: W/System.err(6609): java.lang.IllegalArgumentException: File /storage/emulated/0/com.example.pattern1/myfile.txt contains a path separator
The source code is given below:
protected void writeToFile(String string){
File patternDirectory = new File(Environment.getExternalStorageDirectory().getAbsolutePath().toString()+"/com.example.pattern1/myfile.txt");
patternDirectory.mkdirs();
FileOutputStream outputStream;
try {
outputStream = openFileOutput(patternDirectory.getAbsolutePath().toString(), Context.MODE_APPEND);
outputStream.write(string.getBytes());
TextView t = (TextView)findViewById(R.id.bottomMidText);
t.setText(patternDirectory.getAbsolutePath().toString());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
I would appreciate if someone can help identify the problem.
The openFileInput method will not accept path separators.('/')
it accepts only the name of the file which you want to open/access. so change the statement
outputStream = openFileOutput(patternDirectory.getAbsolutePath().toString(), Context.MODE_APPEND);
to
outputStream = new FileOutputStream (new File(patternDirectory.getAbsolutePath().toString()), true); // true will be same as Context.MODE_APPEND
One problem may be the fact that you do:
Environment.getExternalStorageDirectory().getAbsolutePath().toString()+"/com.example.pattern1/myfile.txt"
You create a directory that has name myfile.txt
I have a problem saving a file in android, the FileOutputStream keeps falling back to a FileNotFoundException and thus won't write the file to the external storage.
Yes I do have permission set in the manifest:
uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
I've added the code below of the function, can someone explain to me what is going wrong, if it is that it is trying to overwrite an existing file, is there a way to replace that file (the name needs to be static)?
(tips on making the code look nicer are welcome as well)
Bitmap savebitmap = Bitmap.createBitmap(drawView.getDrawingCache());
File mediaStorageDir = new File(Environment.getExternalStorageDirectory()+"/Android/data/"+getApplicationContext().getPackageName()+"/Files");
if (!mediaStorageDir.exists()){
mediaStorageDir.mkdir();
}
File pictureFile = new File(Environment.getExternalStorageDirectory()+"/Android/data/"+getApplicationContext().getPackageName()+"/Files"+File.separator+"Tempsave.png");
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
savebitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.flush();
fos.close();
}
catch (FileNotFoundException e) {}
catch (IOException e) {}
Kudos to Guillaume and theV0ID for leading me to the most efficient correct answer.
Below is the example code editted to the working version.
Bitmap savebitmap = Bitmap.createBitmap(drawView.getDrawingCache());
File pictureFile = new File(Environment.getExternalStorageDirectory()+"/Android/data/"+getApplicationContext().getPackageName()+"/Files"+File.separator+"Tempsave.png");
pictureFile.getParentFile().mkdirs();
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
savebitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.flush();
fos.close();
}
catch (FileNotFoundException e) {}
catch (IOException e) {}
Try this :
File pictureFile = new File(Environment.getExternalStorageDirectory()+"/Android/data/"+getApplicationContext().getPackageName()+"/Files"+ File.separator + "Tempsave.png");
pictureFile.getParentFile().mkdirs();
You need to create the file directories if they don't exist. If not the FileOutputStream will throw a FileNotFoundException
The problem:
I'm getting a Base64-Encoded String of raw PDF data from a web service (this data is housed in my String array pdfData). I have to use this data display the PDF in a PDF viewer (I happen to be using the included 'ThinkFree PDF Viewer' since I'm working on an Android application, but lets generalize and say any PDF viewer will do). Note that I'm accessing the 0th element of this array just for testing purposes (to make sure I can at least pull up 1 PDF before writing the code to pull up all the PDFs).
The code is within a class. First the method createFile is called, then intentOpenPDF:
import org.apache.commons.codec.binary.Base64;
File file;
FileOutputStream outputStream;
private byte[] decodedContent;
private String[] pdfData;
private String[] pdfFileName;
public void createFile() {
decodedContent = Base64.decodeBase64(pdfData[0].getBytes());
try {
File path = new File(getFilesDir(), "PDFs");
if (!path.exists()) {
path.mkdirs();
}
file = new File(path, pdfFileName[0]);
outputStream = new FileOutputStream(file);
outputStream.write(decodedContent);
outputStream.close();
}
catch (FileNotFoundException ex) {
ex.printStackTrace();
}
catch (IOException ex) {
ex.printStackTrace();
}
finally {
// Make absolutely certain the outputStream is closed
try {
if (outputStream != null) {
outputStream.close();
}
}
catch (IOException ex) {
ex.printStackTrace();
}
}
}
public void intentOpenPDF() {
// Make sure the file exists before accessing it:
if (file.exists()) {
Uri targetUri = Uri.fromFile(file);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(targetUri, "application/pdf");
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
}
}
The error:
Error opening file. It does not exist or cannot be read.
I have a break point set inside the conditional statement that checks if the file exists (within the intentOpenPDF method), and it IS passing this check.
The path produced by calling getFilesDir() leads a protected directory (file:///data/data/), where only files created with openFileOutput(String, int) are stored. I am not creating the file this way. The solution in my case is to use getExternalFilesDir(null).getAbsolutePath() instead, which will give you a path a directory internal to the application (/storage/emulated/0/Android/data/). No permissions are required to read or write to this path.
Considering your error message:
It does not exist or cannot be read.
as you verified it exists (first possible cause), it's certainly not readable (second possible cause).
I want to create a .txt file and store it on the external storage of the Android phone. I added the permission to my Android Manifest. When I run the code it doesn't give me any error but the file is never created. Not sure what I am doing wrong.
public void createExternalStoragePrivateFile(String data) {
// Create a path where we will place our private file on external
// storage.
File file = new File(myContext.getExternalFilesDir(null), "state.txt");
try {
FileOutputStream os = null;
OutputStreamWriter out = null;
os = myContext.openFileOutput(data, Context.MODE_PRIVATE);
out = new OutputStreamWriter(os);
out.write(data);
os.close();
if(hasExternalStoragePrivateFile()) {
Log.w("ExternalStorageFileCreation", "File Created");
} else {
Log.w("ExternalStorageFileCreation", "File Not Created");
}
} catch (IOException e) {
// Unable to create file, likely because external storage is
// not currently mounted.
Log.w("ExternalStorage", "Error writing " + file, e);
}
}
you need an appropriate permission:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
File file = new File(myContext.getExternalFilesDir(null), "state.txt");
try {
FileOutputStream os = new FileOutputStream(file, true);
OutputStreamWriter out = new OutputStreamWriter(os);
out.write(data);
out.close();
}
I was able to create the file on the external storage by using the code below:
public void createExternalStoragePrivateFile(String data) {
// Create a path where we will place our private file on external
// storage.
File file = new File(myContext.getExternalFilesDir(null), "state.txt");
try {
FileOutputStream os = new FileOutputStream(file);
OutputStreamWriter out = new OutputStreamWriter(os);
out.write(data);
out.close();
if(hasExternalStoragePrivateFile()) {
Log.w("ExternalStorageFileCreation", "File Created");
} else {
Log.w("ExternalStorageFileCreation", "File Not Created");
}
} catch (IOException e) {
// Unable to create file, likely because external storage is
// not currently mounted.
Log.w("ExternalStorage", "Error writing " + file, e);
}
}