Android: problem in Decoding bitmap image

Question

In my project I have a Picture that through program, I extracted pixels, manipulate those pixels and then saved it in my package. The way that I saved it, is:

private void createPicture()
{
    System.out.println("Inside createPicture");
    System.out.println(contextPath);
    try{
        FileOutputStream fos = new FileOutputStream(contextPath + "/" + picName);
        DataOutputStream dos = new DataOutputStream(fos); 

        for(int i=0; i<splitedPixel.length; i++)
            dos.writeByte(splitedPixel[i]);

        dos.flush();
        dos.close();
    }
    catch(IOException e){
        System.out.println("IOException : " + e);
    }
    System.out.println("Picture Created.");
}

so, it saves my picture in this directory

/data/data/my_package_name/files/myPic.bmp

Now, I want to read this new Picture and extract pixels of this picture. I have used this method:

public Stego(Context context)
{
    //Instantiate an ImageView and define its properties
    contextPath = context.getFilesDir().getAbsolutePath();
    image = BitmapFactory.decodeFile(contextPath + "/" + picName);

    System.out.println("Image= " + image);
    imWidth  = image.getWidth();
    imHeight = image.getHeight();
    getMaxMessageChars();
    System.out.println("Width: " + imWidth);
}

Program crashes here. logcat indicates that the result for the image is null and when program reaches to getWidth crashes.

are these ways for writing and reading correct? Can I go to the directory through emulator to check Whether this picture is created or not?

Thanks

Answer 1

I think you should close fos stream in the createPicture() method.

BitmapFactory.decode*() methods return null in case of error. So it's better to check for null after decoding.

As far as I know you can save a file from the Android internal storage only on an emulator or a rooted device. This can be done using Eclipse's DDMS Perspective or ddms utility from Android SDK toolchain. Just click Device->File Explorer and pull your files from a device.

If you want to get a file from a non-rooted device, you'd better save it to the external storage (sdcard). In this case you can connect your device to a computer like external hard drive.