Question

Method1 (Not working)
I declared an Imageview in XML

<ImageView
    android:id="@+id/imageView1" 
    android:layout_height="wrap_content"
    android:layout_weight="0.21" 
    android:layout_width="100dp" 
    android:layout_gravity="center">
</ImageView>

Then I declare it in code

ImageView iv=(ImageView)findViewById(R.id.imageView1);

Then I download a image from web (image)

iv.setImageBitmap(image);
setContentView(iv);

Method2 (working)

Instead of XML i just declare

ImageView iv=new ImageView(this);

Then I download a image from web (image)

iv.setImageBitmap(image);
 setContentView(iv);

The question why Method1 doesn’t work and Method2 works?

Answer 1

Method 1 should give a force close error as you are using findViewById before setContentView.
FindViewById tries to find the view inside the layout you specified in setContentView. So setContentView should be called first.