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

This is my code for creating the 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 a file to my server just by calling the path String path = "/data/data/lalallalaa.txt";

I am getting a logcat error:

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 the file that it "supposedly" has already been created.

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4 answers


Are you sure the file has already been created?

Try adding this:



File file = new File(path);
if (!file.exists()) {
  file.createNewFile();
}
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/ data / data / is a privileged directory in Android. Applications cannot write to or read from this directory.



Instead, you should use context.getFilesDir()

to find a valid filename to use.

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I think you better add a tight FileOutputStream function for clear code

It works great.

try {
    if (!File.exists()) {
        File.createNewFile();
    }
    FileOutputStream fos = new FileOutputStream(File);
    fos.write(bytes);
    fos.close();
} catch (Exception e) {
    Log.e(TAG, e.getMessage());
}
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This exception is thrown if either the file does not exist or if you are trying to write to a read-only file. Also try using the fully qualified pathname and see if the same exception occurred (to check if you gave the correct relative path).

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