CODEWITHSUNDEEP
androidandroid-linearlayoutexpandablelistviewclasscastexception
Christopher Perry
Christopher Perry

Reputation: 39225

Android: ClassCastException when adding a header view to ExpandableListView

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?

Upvotes: 43

Views: 16400

Answers (4)

Cheng
Cheng

Reputation: 785

You should put parent view to your inflated view. 

ListView listview = (ListView) findViewById(R.id.listview);
headerView = View.inflate(this, R.layout.header, listview, false); // set listview as parent view
listview.addHeaderView(headerview);

Upvotes: 0

Adeel Ahmad
Adeel Ahmad

Reputation: 969

Even though the above answer might work for many, there is still a better explanation. ClassCastException is the normal behaviour after calling listview.addHeaderView or listview.addFooterView.

The reason is that the initial adapter is wrapped in the HeaderViewListAdapter. To get your adapter use this code.

YourAdapter ya = (YourAdapter) ((HeaderViewListAdapter)lv.getAdapter()).getWrappedAdapter();

Code taken from here

Upvotes: 5

Denis Kutlubaev
Denis Kutlubaev

Reputation: 16124

In my case this didn't work. I had to set a footerView to my listView before setting it's adapter. First I initialized my loadingView from a layout file in OnCreate method:

LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
loadingView = layoutInflater.inflate(R.layout.loading_view, null);

Then I used this workaround in the same method: 

this.setIsLoading(true);
listView.setAdapter(adapter);
this.setIsLoading(false);

Where

private void setIsLoading(boolean isLoading)
{
    this.isLoading = isLoading;

    if (isLoading) {
        listView.addFooterView(loadingView);
    }
    else {
        listView.removeFooterView(loadingView);
    }
}

Upvotes: 1

Christopher Perry
Christopher Perry

Reputation: 39225

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.

Upvotes: 90

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