Custom Layout with child views

Question

I am getting an error on this. Cannot figure out how to use child views in my custom view (Relative layout).

   <RelativeLayout >   

    <com.xxxxxx.FavouriteImageView
        android:id="@+id/favorite_status"
        android:layout_width="25dp"
        android:layout_height="25dp"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:layout_marginRight="15dp"
        android:clickable="true" >

        <ImageView
            android:id="@+id/favourite_iv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@drawable/yellow_star"
            android:clickable="false" />

        <ProgressBar
            android:id="@+id/favorite_spinner"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="gone"
            android:clickable="false" />

    </com.xxxxxxxx.FavouriteImageView>

public class FavouriteImageView extends RelativeLayout{

ImageView star;
ProgressBar spinner;
boolean isFavorite;

Context context;

public FavouriteImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    this.context= context;
    findChildViews();}

public FavouriteImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.context= context;
    findChildViews();
}

public FavouriteImageView(Context context) {
    super(context);
    this.context= context;
    findChildViews();}


private void findChildViews(){

    star = (ImageView) findViewById(R.id.favourite_iv);
    spinner = (ProgressBar) findViewById(R.id.favorite_spinner);
}

}

The problem is I keep on getting NPE when ever I try to use star or spinner. Dont know how to use the child views.

Answer 1

You cannot find these views in constructor. The child views are not yet added to the parent.

For your case, you can override the addView() method and do the same :

@Override
public void addView(View child, int index, LayoutParams params) {
    super.addView(child, index, params);
    switch (child.getId()) {
    case R.id.favourite_iv:
        spinner = (ProgressBar) child;
        break;
    case R.id.favorite_spinner:
        star = (ImageView) child;
        break;
    }
}