How do I write a byte array to a file in Android?

Question

This is my code to create a file.

public void writeToFile(byte[] array) 
{ 
    try 
    { 
        String path = "/data/data/lalallalaa.txt"; 
        FileOutputStream stream = new FileOutputStream(path); 
        stream.write(array); 
    } catch (FileNotFoundException e1) 
    { 
        e1.printStackTrace(); 
    } 
}

When I try to send my file to my server by just calling the path String path = "/data/data/lalallalaa.txt";

I get this logcat error message:

03-26 18:59:37.205: W/System.err(325): java.io.FileNotFoundException: /data/data/lalallalaa.txt

I don't understand why it can't find a file that is "supposedly" created already.

don't forget to close the stream afterwards – ratchet freak Mar 26 '12 at 19:08 — ratchet freak, Mar 26 '12 at 19:08

score 18 · Answer 1 · edited May 28 '20 at 07:10

18

I think you'd better add close function of FileOutputStream for clear code

It works me perfectly

try {
    if (!file.exists()) {
        file.createNewFile();
    }
    FileOutputStream fos = new FileOutputStream(file);
    fos.write(bytes);
    fos.close();
} catch (Exception e) {
    Log.e(TAG, e.getMessage());
}

edited May 28 '20 at 07:10

shb

5,957
2
15
32

answered Feb 18 '16 at 01:13

Trần Thị Diệu My

1,323
22
23

score 12 · Accepted Answer · answered Mar 26 '12 at 19:10

12

Are you sure the file is created already?

Try adding this:

File file = new File(path);
if (!file.exists()) {
  file.createNewFile();
}

answered Mar 26 '12 at 19:10

Churk

4,556
5
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37

Yes, that was correct. I was not actually creating a new file. Did not know about that method and didn't know that it was necessary. Thanks – EGHDK Mar 26 '12 at 20:48

score 7 · Answer 3 · answered Mar 26 '12 at 19:47

7

/data/data/ is a privileged directory in Android. Apps can't write to this directory or read from it.

Instead, you should use context.getFilesDir() to find a valid filename to use.

answered Mar 26 '12 at 19:47

Tom Meyer

141
3

score 0 · Answer 4 · answered Mar 26 '12 at 19:28

0

This exception is thrown if either the file does not exist or if you are trying to write to a file that is read-only. Also try using full path name and see if the same exception occurs (to check if you gave the correct relative path).

answered Mar 26 '12 at 19:28

kurra

13
2

How do I write a byte array to a file in Android?

4 Answers4

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