How can I remove a button or make it invisible in Android?

To remove button in java code:

Button btn=(Button)findViewById(R.id.btn);
btn.setVisibility(View.GONE);

To transparent Button in java code:

Button btn=(Button)findViewById(R.id.btn);
btn.setVisibility(View.INVISIBLE);

To remove button in Xml file:

<Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="gone"/>

To transparent button in Xml file:

<Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="invisible"/>