ImageView中是否含有图像的检验

Drawable drawable = imageView.getDrawable();
if (drawable == null) {
    // ImageView中没有图像
} else {
    // ImageView中含有图像
}

Drawable placeholder = getResources().getDrawable(R.drawable.placeholder);
imageView.setImageDrawable(placeholder);

Drawable drawable = imageView.getDrawable();
if (drawable == placeholder) {
    // ImageView中没有设置具体的图像
} else {
    // ImageView中含有图像
}

Bitmap placeholder = BitmapFactory.decodeResource(getResources(), R.drawable.placeholder);
imageView.setImageBitmap(placeholder);

Drawable drawable = imageView.getDrawable();
if (drawable instanceof BitmapDrawable) {
    Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
    if (bitmap == placeholder) {
        // ImageView中没有设置具体的图像
    } else {
        // ImageView中含有图像
    }
} else {
    // ImageView中没有设置具体的图像
}