Caused by java.lang.NullPointerException: Attempt to invoke virtual method 'int android.graphics.Bitmap.getWidth()' on a null object reference

Question

I have BitmapScalingHelper.java:

public class BitmapScalingHelper
{
    public static Bitmap decodeResource(Resources res, int resId, int dstWidth, int dstHeigh         


        

Answer 1

The problem you are facing is that you are trying to getWidth() on your unscaledBitmap in the createScaledBitmap function. Clearly, your unscaledBitmap is null sometimes; and calling getWidth() is causing the Null Pointer exception.

The root cause is that decodeResource is returning you a null for whatever reason.

The reasons can include -

1. No read permission
2. The image file is corrupt
3. There is not enough memory to decode the file
4. The resource does not exist
5. Invalid options specified in the options variable.

I'd suggest that you modify your code to include a null-check on the decoded bitmap, log it and debug from there on the specific devices that you see the error occurring.

It may also be that your options variable that you are re-using is being interpreted differently in the second call to decodeResource. You might try passing a null there.

The modified code should be as follows -

public class BitmapScalingHelper
{
    public static Bitmap decodeResource(Resources res, int resId, int dstWidth, int dstHeight)
    {
        Options options = new Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);
        options.inJustDecodeBounds = false;

        options.inSampleSize = calculateSampleSize(options.outWidth, options.outHeight, dstWidth,
                dstHeight);

        options = new Options(); 
        //May use null here as well. The funciton may interpret the pre-used options variable in ways hard to tell.
        Bitmap unscaledBitmap = BitmapFactory.decodeResource(res, resId, options);

        if(unscaledBitmap == null)
        {
            Log.e("ERR","Failed to decode resource - " + resId + " " + res.toString());
            return null;
        }

        return unscaledBitmap;
    }
}