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Android: ClassCastException when adding a header view to ExpandableListView

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By User



I'm trying to add a header to an ExpandableListView like so:







headerView = View.inflate(this, R.layout.header, null);

expandableListView.addHeaderView(headerView);

expandableListView.setAdapter(new SectionedAdapter(this));







Which gives me the following error:







12-08 16:23:42.354: ERROR/AndroidRuntime(421): Caused by: java.lang.ClassCastException: android.widget.LinearLayout$LayoutParams 12-08 16:23:42.354: ERROR/AndroidRuntime(421): at android.widget.ListView.clearRecycledState(ListView.java:504) 12-08 16:23:42.354: ERROR/AndroidRuntime(421): at android.widget.ListView.resetList(ListView.java:490) 12-08 16:23:42.354: ERROR/AndroidRuntime(421): at android.widget.ListView.setAdapter(ListView.java:422) 12-08 16:23:42.354: ERROR/AndroidRuntime(421): at android.widget.ExpandableListView.setAdapter(ExpandableListView.java:475)







This is happening at the call to expandableListView.setAdapter(new SectionedAdapter(this)) , but I can't figure out why. Any ideas?



Source: Tips4all
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  1. Tips For AllApril 10, 2012 at 10:48 AM

    Ok, I figured this one out. I got rid of the runtime error by programatically setting the View's LayoutParams to ListView LayoutParams, like so:

    headerView.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.FILL_PARENT, ListView.LayoutParams.WRAP_CONTENT));


    before adding the view. The reason being is found in the Android docs:

    http://developer.android.com/reference/android/view/View.html#setLayoutParams(android.view.ViewGroup.LayoutParams)

    which states that:


    These supply parameters to the
    parent of this view specifying how it should be arranged. There are many
    subclasses of ViewGroup.LayoutParams,
    and these correspond to the different
    subclasses of ViewGroup that are
    responsible for arranging their
    children.


    So basically, if you are adding a view to another, you MUST set the LayoutParams of the view to the LayoutParams type that the parent uses, or you will get a runtime error.

    ReplyDelete

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