Question

I’m trying to display an ImageView in a dialog, I’ve followed several examples but none of them seem to work as when I open the dialog the app closes.

<ImageView android:id="@+id/image"
           android:contentDescription="@string/desc1"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content" />

This is what I have in my MainActivity

button1.setOnLongClickListener(new OnLongClickListener()
    {
        public boolean onLongClick(View v)
        {
            AlertDialog dialog = new AlertDialog.Builder(MainActivity.this).create();

            dialog.setTitle("Title");
            ImageView img = (ImageView) findViewById(R.id.image);
            img.setImageResource(R.drawable.dust);
            dialog.setView(img);

            dialog.show();
            return false;

        }


    });

}

Using this new code I have been able to display the dialog with the image inside and I have also been able to rotate the image

   button1.setOnLongClickListener(new OnLongClickListener()
    {
        public boolean onLongClick(View v)
        {
            Dialog dialog = new Dialog(MainActivity.this);
            LayoutInflater inflater = LayoutInflater.from(MainActivity.this);


            RotateAnimation anim = new RotateAnimation(0f, 360f, 200f, 200f);
            anim.setInterpolator(new LinearInterpolator());
            anim.setRepeatCount(Animation.INFINITE);
            anim.setDuration(10000);

            dialog.setTitle("You have found the easter egg!");
            View view = inflater.inflate(R.layout.activity_main2, null);
            dialog.setContentView(view);
            view.startAnimation(anim);

            dialog.show();
            return false;

        }


    });

}

Answer 1

when I open the dialog the app closes. 

Because your dialog ImageView img is null

ImageView img = (ImageView) dialog.findViewById(R.id.image); // <--- img is not visible through dialog..
img.setImageResource(R.drawable.dust); // <--- this line throw exception

Just Change your code like this,

AlertDialog dialog = new AlertDialog.Builder(MainActivity.this).create();
LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
dialog.setTitle("Title");
View view = inflater.inflate(R.layout.<xml_image>, null); // xml Layout file for imageView
ImageView img = (ImageView) view.findViewById(R.id.image);
img.setImageResource(R.drawable.dust);
dialog.setView(view);
dialog.show();