Create custom viewGroup with custom layout + one child

Question

I would like to create a component which would allow me to simplify a ViewFlipper.

The first view of my flipper is a progressBar, which show to the user that the content is loading, and the second view in my flipper is my content (for example another layout). In other words, I want to simplify this:

<ViewFlipper xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/myContent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"  />

</ViewFlipper>

The first view (the progressBar) is always the same for all my activities, so the component I want to create could be used like that (file layout-activity.xml):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

    <com.example.fred.myapplication.MyCustomComponent
        android:id="@+id/myComponent"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/myContent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            />

    </com.example.fred.myapplication.MyCustomComponent>

</LinearLayout>

I started to create the component like that:

public class MyCustomComponent extends RelativeLayout {

ViewFlipper myFlipper;

public MyCustomComponent(Context context) {
    super(context);
}

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

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

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);

    //the main template
    View template = inflate(getContext(), R.layout.template, null);

    //get the viewFlipper from my template
    myFlipper = (ViewFlipper) template.findViewById(R.id.myFlipper);

    //add the first child of my custom component to the view flipper
    myFlipper.addView(getChildAt(0));
}

/**
 * Show the progressBar
 */
public void showProgressBar(){
    myFlipper.setDisplayedChild(0);
}
/**
 * Show my custom content which can be a textview in my example but also a LinearLayout for example...
 */
public void showContent(){
    myFlipper.setDisplayedChild(1);
}
}

And the template.xml which contains the viewFlipper is:

<?xml version="1.0" encoding="utf-8"?>
<ViewFlipper xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/myFlipper"
android:layout_width="match_parent"
android:layout_height="match_parent">

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</ViewFlipper>

In my activities I want to use my custom component like that:

public class MainActivity extends Activity {

MyCustomComponent myCustomComponent;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_activity);

    myCustomComponent = (MyCustomComponent) findViewById(R.id.myComponent);
    myCustomComponent.showProgressBar();
    loadLongStuff();
}

private void loadLongStuff() {
    //processing... long stuff
    //working again...

    //at the end, show my content loaded
    myCustomComponent.showContent();
}
}

I created each files I wrote here but it doesn't work: my app crash but I don't have any stack trace.... can you tell me what's wrong?

Thank you.

Answer 1

In case you haven't been able to figure this out yet, I believe the problem is that you're missing an onMeasure method.

See Google's example for reference

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    // Do something
}

Again, Google's Example offers some great demonstrations on how to use this method and what to do with it.

Cheers!