Android LayoutInflater fails quietly for LinearLayout - android-layout

Question

I'm using a LayoutInflater to retrieve a view from the resources, then insert it into a programmaticly constructed custom ViewGroup. It works fine when the resource contains only a TextView. But when the resource contains a LinearLayout it fails quietly - no exception is thrown, the custom ViewGroup components appear but the View from the resource does not appear.
The custom ViewGroup puts coloured borders around an inner View. Here is the class:
package ask.question;
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
public class BorderViewGroup extends ViewGroup {
private View leftBorder ;
private View topBorder ;
private View rightBorder ;
private View bottomBorder ;
private View innerView = null ;
public BorderViewGroup(Context context) {
super(context);
initBorderViewGroup(context);
}
public BorderViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
initBorderViewGroup(context);
}
public BorderViewGroup(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initBorderViewGroup(context);
}
private void initBorderViewGroup(Context context) {
leftBorder = new View(context);
topBorder = new View(context);
rightBorder = new View(context);
bottomBorder = new View(context);
addView(leftBorder);
addView(topBorder);
addView(rightBorder);
addView(bottomBorder);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// Should probably use argument 'changed'.
int width = r - l;
int height = this.getHeight();
leftBorder.layout(0, 0, 2, height);
topBorder.layout(0, 0, width, 2);
rightBorder.layout(width-2, 0, width, height);
bottomBorder.layout(0, height-2, width, height);
if (innerView != null) {
innerView.layout(2, 2, width-2, height-2);
}
}
/*
* Sets the view to be displayed within the borders.
* Subsequent calls will replace the view.
* #param view View to be displayed. May be null.
*/
public void setInnerView(View view) {
if (innerView!=null) {
this.removeView(innerView);
}
this.innerView = view ;
if (innerView!=null) {
addView(innerView);
}
}
/*
* Sets the colors for each of the four borders.
* A color value of zero will be ignored, leaving that border unchanged.
* Note: colors can be specified in hexadecimal. Red is 0xFFFF0000. In general, the first two hex digits control transparency, the next red, green and blue.
*/
public void setBorderColors(int leftColor, int topColor, int rightColor, int bottomColor) {
if (leftColor!=0) leftBorder.setBackgroundColor(leftColor);
if (topColor!=0) topBorder.setBackgroundColor(topColor);
if (rightColor!=0) rightBorder.setBackgroundColor(rightColor);
if (bottomColor!=0) bottomBorder.setBackgroundColor(bottomColor);
}
/*
* Sets the color of the border around the innerView.
* A color value of zero will be ignored, leaving the border unchanged.
* Note: colors can be specified in hexadecimal. Red is 0xFFFF0000. In general, the first two hex digits control transparency, the next red, green and blue.
*/
public void setBorderColor(int color) {
setBorderColors(color, color, color, color);
}
}
It works fine when the resource is a TextView. Here is the Activity's onCreate() method, and the resource file flat.xml.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
BorderViewGroup bvg = new BorderViewGroup(this);
LayoutInflater inflater = LayoutInflater.from(this);
//View mainView = inflater.inflate(R.layout.flat, null);
View mainView = inflater.inflate(R.layout.nested, null);
View objectView = mainView.findViewById(R.id.object_view);
if (mainView==null) throw new RuntimeException("mainView is null");
if (objectView==null) throw new RuntimeException("objectView is null");
bvg.setBorderColors(0xFFFF0000, 0xFF00F0F0, 0xFF00FF00, 0xFF0000FF);
setContentView(bvg);
bvg.setInnerView(objectView);
}
and
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/object_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="View from resource xml." />
The above works fine. It displays coloured borders, and the text "View from resource xml.".
But it fails quietly if the resource file contains a LinearLayout. Here is the Activity's onCreate() method, and the resource file nested.xml.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
BorderViewGroup bvg = new BorderViewGroup(this);
LayoutInflater inflater = LayoutInflater.from(this);
View mainView = inflater.inflate(R.layout.flat, null);
//View mainView = inflater.inflate(R.layout.nested, null);
View objectView = mainView.findViewById(R.id.object_view);
if (mainView==null) throw new RuntimeException("mainView is null");
if (objectView==null) throw new RuntimeException("objectView is null");
bvg.setBorderColors(0xFFFF0000, 0xFF00F0F0, 0xFF00FF00, 0xFF0000FF);
setContentView(bvg);
bvg.setInnerView(objectView);
}
and
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/object_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/tv"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="A TextView from resource XML." />
<TextView
android:id="#+id/here"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="A second TextView." />
</LinearLayout>
This does not work. It displays the coloured borders, but not the text.
Why does one work, and not the other? Even better, how can the LinearLayout be made to work?
I've followed the inflater code from XML Inflater not seeing any of the views?. I've removed some arguments from the inflation because they cause already-have-parent errors. The TextView works without them.