[android] Clear listview content?

I have a little problem with ListView. How do I clear a ListView content, knowing that it has a custom adapter?

edit - the custom adapter class extends BaseAdapter, it looks like this:

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MyAdapter extends BaseAdapter {

    private Activity activity;
    private String[] data;
    private static LayoutInflater inflater = null;

    public MyAdapter(Activity a, String[] str) {
        activity = a;
        data = str;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public static class ViewHolder {
        public TextView text;
    }

    @Override
    public int getCount() {
        return data.length;
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        View v = view;
        ViewHolder holder;
        if (v == null) {
            v = inflater.inflate(R.layout.rowa, null);
            holder = new ViewHolder();
            holder.text= v.findViewById(R.id.dexter);
            v.setTag(holder);
        } else {
            holder = v.getTag();
        }

        holder.text.setText(data[position]);

        return v;
    }

}

Remove your items from your custom adapter and call notifyDataSetChanged().

I guess you passed a List or an Array to the Adapter. If you keep the instance of this added collection, you can do a

collection.clear();
listview.getAdapter().notifyDataSetChanged();

this'll work only if you instantiated the adapter with collection and it's the same instance.

Also, depending on the Adapter you extended, you may not be able to do this. SimpleAdapter is used for static data, thus it can't be updated after creation.

PS. not all Adapters have a clear() method. ArrayAdapter does, but ListAdapter or SimpleAdapter don't

As of Android versions M and N, following works for me and would be the correct approach. Emptying the ListView or setting the Adapter to null is not the right approach and would lead to null pointer issue, invalid ListView and/or crash of the app.

Simply do:

    mList.clear();
    mAdapter.notifyDataSetChanged();

i.e. first you clear the list altogether, and then let the adapter know about this change. Android will take care of correctly updating the UI with an empty list. In my case, my list is an ArrayList.

In case you are doing this operation from a different thread, run this code on the UI thread:

    runOnUiThread(mRunnable);

Where mRunnable would be:

    Runnable mRunnable = new Runnable() {
        public void run() {
            mList.clear();
            mAdapter.notifyDataSetChanged();
        }
    };;

It's simple .First you should clear your collection and after clear list like this code :

 yourCollection.clear();
 setListAdapter(null);

Call clear() method from your custom adapter .

There is a solution for the duplicate entry in listview. You have to declare the onBackPress()-method on your activity and write down the highlight code given below:

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    super.onBackPressed();
    **

    attendence_webdata.clear(); list.setAdapter(null);
    --------------------------------------------------

    **
 }

You need to call both clear() from ArrayAdapter and notifyDataSetChanged() both.

Below is link click

Just put the code ListView.Items.Clear(); on your method

Simple its works me:)

YourArrayList_Object.clear();