Question

I have a custom LinearLayout. Inside that layout I want to place a couple widgets. I could create the widgets at runtime, but would rather load them from XML.

What I have below works, but I believe it is creating two LinearLayouts, one inside the other. I’d like to simply, in this example, create the Button and EditText inside the CustomLayout. Using XML, how can I do this?

Here is a bit more detail (edit: below this example, I’ve included a corrected version):

<com.example.test.MyActivity
  ... />
  <LinearLayout
    ... />
    <com.example.test.CustomLayout  ***** this is the custom linear layout
      android:id="@+id/custom"
      android:orientation="horizontal"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content" />
    <View
      ... other stuff ... />
</com.example.test.MyActivity>

And here’s the XML for the CustomLayout contents:

<LinearLayout
  ... />
  <Button
    ... />
  <EditText
    ... />
</LinearLayout>

And finally, the code for LinearLayout:

public class CustomLayout extends LinearLayout
{
  public CustomLayout (Context context, AttributeSet attrs)
  {
    super(context, attrs);
    Activity act = (Activity)context;
    LayoutInflater inflater = act.getLayoutInflater();
    View view = inflater.inflate (R.layout.custom_layout, this, false);
    addView (view);
  }
  ...
}

Corrected Version

<com.example.test.MyActivity
  ... />
  <LinearLayout
   android:id="@+id/outer_layout
   ... />

    ... other stuff ... 
  </LinearLayout>
</com.example.test.MyActivity>

And here’s the XML for the CustomLayout contents:

<merge
  ... />
  <Button
    ... />
  <EditText
    ... />
</merge>

The code to instantiate CustomLayout

public void addCustomLayout()
{
  LinearLayout outerLayout = (LinearLayout) findViewById (R.id.outer_layout);
  CustomLayout customLayout = new CustomLayout (getContext(), null);
  outerLayout.addView (customLayout, 0);
}

And finally, the code for CustomLayout:

public class CustomLayout extends LinearLayout
{
  public CustomLayout (Context context, AttributeSet attrs)
  {
    super(context, attrs);
    Activity act = (Activity)context;
    LayoutInflater inflater = act.getLayoutInflater();
    View view = inflater.inflate (R.layout.custom_layout, this, true);
  }
  ...
}

Answer 1

What I have below works, but I believe it is creating two
LinearLayouts, one inside the other.

Indeed you’ll have an extra LinearLayout(from the xml layout which contains the Button and the EditText) in CustomLayout. To avoid this you have at your disposal the merge tag. You’ll use it like this:

<merge
  ... />
  <Button
    ... />
  <EditText
    ... />
</merge>

Then in your CustomLayout constructor:

super(context, attrs);
Activity act = (Activity)context;
LayoutInflater inflater = act.getLayoutInflater();
View view = inflater.inflate (R.layout.custom_layout, this, true); // addView is not needed anymore