Searchview.setOnQueryTextListener NullPointException

Question

This is the searchview in MainActivity

searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String text) {
            return false;
        }

        @Override
        public boolean onQueryTextChange(String text) {
            servantAdapter.getFilter().filter(text);
            //Toast.makeText(MainActivity.this,text,Toast.LENGTH_SHORT).show();
            return true;
        }
    });
}

And This is the Adapter

public class ServantAdapter extends RecyclerView.Adapter<ServantAdapter.ViewHolder>implements Filterable {
private List<Servant> mServant;
 @Override
public Filter getFilter() {//The front omitted...
    return new Filter() {
        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults filterResults) {
            mServant = (List<Servant>) filterResults.values;
            ServantAdapter.this.notifyDataSetChanged();
        }
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            List<Servant> filteredResults = null;
            if (constraint.length() == 0) {
                filteredResults = mServant;
            } else {
                filteredResults = getFilteredResults(constraint.toString().toLowerCase());
            }

            FilterResults results = new FilterResults();
            results.values = filteredResults;

            return results;
        }

    };
}
protected List<Servant> getFilteredResults(String constraint) {
    List<Servant> results = new ArrayList<>();

    for (Servant item : mServant) {
        if (item.getName().toLowerCase().contains(constraint)) {
            results.add(item);
        }
    }
    return results;
}

Why when I run this program and imput something in the searchview the program is shut dowm and ReportErrors java.lang.NullPointerException: Attempt to invoke virtual method 'android.widget.Filter com.example.a76959.tired.ServantAdapter.getFilter()' on a null object reference

But if I use the Toast in the code ,the program can run regular and toast the message what I input（I didnt take the searchview in Toolbar or ActionBar,I only put it on the top of recyclerview in MainActivity.xml,I don't know if it has any effect ） Who can help me...(Thanks for read my poor English Orz..)

score 0 · Accepted Answer · answered Oct 01 '17 at 15:42

0

When you are using servantAdapter.getFilter().filter(text); make sure the variable servantAdapter has been instantiated properly and is not null.

Use:

if (servantAdapter != null){
    servantAdapter.getFilter().filter(text);
}

Or:

if (servantAdapter == null){
    servantAdapter = new servantAdapter(/*params*/);
}
servantAdapter.getFilter().filter(text);

answered Oct 01 '17 at 15:42

Nabin Bhandari

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Thanks ,the problem solved,but what do you konw what should I do the servantAdapter's value is always null... – L.M.Orz Oct 01 '17 at 16:00
If it is a global variable, using the 2nd approach, it will not be null again until you explicitly make it. – Nabin Bhandari Oct 01 '17 at 16:04

Searchview.setOnQueryTextListener NullPointException

1 Answers1