Android and android Official Website

Android and android Official Website
Check whether the image of ImageView is successfully loaded.

Address: http://blog.csdn.net/caroline_wendy

JudgmentImageView ImageWhether the image exists. If the image is not loaded successfully, the default image is displayed.

If (mPhotoView. getDrawable () = null) {// Toast. makeText (getActivity (), "image loading failed", Toast. LENGTH_SHORT ). show (); mPhotoView. setImageDrawable (getResources (). getDrawable (R. drawable. icon_default_user_photo ));}

Conversion between Bitmap, Drawable, Byte, and ID in Android
1. Bitmap is converted to byte

ByteArrayOutputStream out = new ByteArrayOutputStream();bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);byte[] array= out.toByteArray();

2. byte conversion to bitmap

Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

3. bitmap conversion to Drawable

Drawable drawable = new FastBitmapDrawable(bitmap);

4. Drawable conversion to bitmap
A. BitmapDrawable and FastBitmapDrawable use getBitmap directly
B. Draw other types of Drawable TO A bitmap Using Canvas.

      Canvas canvas = new Canvas(bitmap)      drawable.draw(canvas)

5. id conversion graphic. drawable

Drawable drawable = activity.getResources().getDrawable(R.drawable.icon);

6. Convert id to Bitmap

Bitmap bitmap = BitmapFactory. decodeResource (Resources   res, int id)