Using byte array to read in file, then display on ImageView (Android)

Question

I was trying to display a picture file using ImageView, although I knew that I could decode the file to bitmap directly, but I have to do some other thing to it, so I could only choose byte[].

The code looks like this:

File file = new File(getRealPathFromURI(Uri.parse(ImgUri)));
byte[] beforeData = new byte[(int) file.length()];
try {
    FileInputStream fis = new FileInputStream(file);
    int detectEnd = 0;
    while (detectEnd != -1){detectEnd = fis.read(beforeData, 0, 1024);}
    Bitmap b_t = BitmapFactory.decodeByteArray(beforeData, 0, beforeData.length);
    editImgView.setImageBitmap(b_t);
} catch (FileNotFoundException e) {e.printStackTrace();}
    catch (IOException e) {e.printStackTrace();}

I tried to test out if I read in the picture correctly, so I decode in to Bitmap then try to display it, but it does not display any picture at all.

Is there anything that I misunderstood with FileInputStream? PS. I use log.i to check and found that beforeData's length is normal, but the data inside only get: [B@40c4b110 , which is not like a picture's data.

Thanks in Advance, Desolve.

Oops, thanks you siliconeagle, I forgot to consider that part...(At the very beginning I did) However, it seems like it's not where the main problem is... Now the loop looks like:

    while (pos < beforeData.length){
            read = fis.read(beforeData, pos, 1);
            pos += read;
        }

It's stupid and dummy I know, but the code in this block should work properly, right? However, I still couldn't see any picture in my ImageView.

Another PS: The file's path is at /mnt/sdcard/DCIM/Camera/1310368442822.jpg, size 1485847 bytes, would size cause any trouble?

siliconeagle · Accepted Answer · 2011-07-11 12:24:48Z

1

you are only reading data into the first 1024 bytes of the array each loop.

fis.read(beforeData, 0, 1024);

you would have to maintain a position counter (int pos) and use another variable (int read) to detect -1

int read=0;
int pos=0;
while (read!=-1) {
    read= fis.read(beforeData, pos, 1024);
    pos+=read;
}

make sure you close your files (fis.close()) as well...

The best way is :

File tmpImgFile = new File("/path");
BitmapFactory.decodeFile(tmpImgFile.getAbsolutePath());

answered Jul 11, 2011 at 12:24

siliconeagle

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Desolve Over a year ago

Thanks, but there's still problem.

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