Custom ViewGroup example

custom-viewgroup.java

public class MyCustomViewGroup extends RelativeLayout {
    public MyCustomViewGroup(Context context) {
        super(context);
        init(context);
    }

    public MyCustomViewGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public MyCustomViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context);
    }

    @TargetApi(21)
    public MyCustomViewGroup(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        init(context);
    }
  
    private void init(Context context) {
        if(!isInEditMode()) {
           // ...
        }
    }  

    @OnClick(R.id.button)
    public void doSomething() {
        // ...
    }
  
    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        ButterKnife.bind(this);
    }
  
    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        // pretty much `onStart()`
    }
  
    @Override
    protected void onDetachedFromWindow() {
        // pretty much `onStop()`
        super.onDetachedFromWindow();
    }
}

custom-viewgroup.xml

<?xml version="1.0" encoding="utf-8"?>
<fully.qualified.MyCustomViewGroup xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Go to next"/> <!-- centerInParent works because -->
                                    <!-- custom viewgroup is also RelativeLayout -->
</fully.qualified.MyCustomViewGroup>