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listview – List View Filter Android

Posted by: admin March 11, 2020 Leave a comment

Questions:

I have created a list view in android and I want to add edit text above the list and when the user enter text the list will be filtered according to user input

can anyone tell me please if there is a way to filter the list adapter in android ?

How to&Answers:

Add an EditText on top of your listview in its .xml layout file.
And in your activity/fragment..

lv = (ListView) findViewById(R.id.list_view);
    inputSearch = (EditText) findViewById(R.id.inputSearch);

// Adding items to listview
adapter = new ArrayAdapter<String>(this, R.layout.list_item, R.id.product_name,    products);
lv.setAdapter(adapter);       
inputSearch.addTextChangedListener(new TextWatcher() {

    @Override
    public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
        // When user changed the Text
        MainActivity.this.adapter.getFilter().filter(cs);
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) { }

    @Override
    public void afterTextChanged(Editable arg0) {}
});

The basic here is to add an OnTextChangeListener to your edit text and inside its callback method apply filter to your listview’s adapter.

EDIT

To get filter to your custom BaseAdapter you”ll need to implement Filterable interface.

class CustomAdapter extends BaseAdapter implements Filterable {

    public View getView(){
    ...
    }
    public Integer getCount()
    {
    ...
    }

    @Override
    public Filter getFilter() {

        Filter filter = new Filter() {

            @SuppressWarnings("unchecked")
            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {

                arrayListNames = (List<String>) results.values;
                notifyDataSetChanged();
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {

                FilterResults results = new FilterResults();
                ArrayList<String> FilteredArrayNames = new ArrayList<String>();

                // perform your search here using the searchConstraint String.

                constraint = constraint.toString().toLowerCase();
                for (int i = 0; i < mDatabaseOfNames.size(); i++) {
                    String dataNames = mDatabaseOfNames.get(i);
                    if (dataNames.toLowerCase().startsWith(constraint.toString()))  {
                        FilteredArrayNames.add(dataNames);
                    }
                }

                results.count = FilteredArrayNames.size();
                results.values = FilteredArrayNames;
                Log.e("VALUES", results.values.toString());

                return results;
            }
        };

        return filter;
    }
}

Inside performFiltering() you need to do actual comparison of the search query to values in your database. It will pass its result to publishResults() method.

Answer:

Implement your adapter Filterable:

public class vJournalAdapter extends ArrayAdapter<JournalModel> implements Filterable{
private ArrayList<JournalModel> items;
private Context mContext;
....

then create your Filter class:

private class JournalFilter extends Filter{

    @Override
    protected FilterResults performFiltering(CharSequence constraint) {
        FilterResults result = new FilterResults();
        List<JournalModel> allJournals = getAllJournals();
        if(constraint == null || constraint.length() == 0){

            result.values = allJournals;
            result.count = allJournals.size();
        }else{
            ArrayList<JournalModel> filteredList = new ArrayList<JournalModel>();
            for(JournalModel j: allJournals){
                if(j.source.title.contains(constraint))
                    filteredList.add(j);
            }
            result.values = filteredList;
            result.count = filteredList.size();
        }

        return result;
    }
    @SuppressWarnings("unchecked")
    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
        if (results.count == 0) {
            notifyDataSetInvalidated();
        } else {
            items = (ArrayList<JournalModel>) results.values;
            notifyDataSetChanged();
        }
    }

}

this way, your adapter is Filterable, you can pass filter item to adapter’s filter and do the work.
I hope this will be helpful.

Answer:

In case anyone are still interested in this subject, I find that the best approach for filtering lists is to create a generic Filter class and use it with some base reflection/generics techniques contained in the Java old school SDK package. Here’s what I did:

public class GenericListFilter<T> extends Filter {

    /**
     * Copycat constructor
     * @param list  the original list to be used
     */
    public GenericListFilter (List<T> list, String reflectMethodName, ArrayAdapter<T> adapter) {
        super ();

        mInternalList = new ArrayList<>(list);
        mAdapterUsed  = adapter;

        try {
            ParameterizedType stringListType = (ParameterizedType)
                    getClass().getField("mInternalList").getGenericType();
            mCompairMethod =
                    stringListType.getActualTypeArguments()[0].getClass().getMethod(reflectMethodName);
        }
        catch (Exception ex) {
            Log.w("GenericListFilter", ex.getMessage(), ex);

            try {
                if (mInternalList.size() > 0) {
                    T type = mInternalList.get(0);
                    mCompairMethod = type.getClass().getMethod(reflectMethodName);
                }
            }
            catch (Exception e) {
                Log.e("GenericListFilter", e.getMessage(), e);
            }

        }
    }

    /**
     * Let's filter the data with the given constraint
     * @param constraint
     * @return
     */
    @Override protected FilterResults performFiltering(CharSequence constraint) {
        FilterResults results = new FilterResults();
        List<T> filteredContents = new ArrayList<>();

        if ( constraint.length() > 0 ) {
            try {
                for (T obj : mInternalList) {
                    String result = (String) mCompairMethod.invoke(obj);
                    if (result.toLowerCase().startsWith(constraint.toString().toLowerCase())) {
                        filteredContents.add(obj);
                    }
                }
            }
            catch (Exception ex) {
                Log.e("GenericListFilter", ex.getMessage(), ex);
            }
        }
        else {
            filteredContents.addAll(mInternalList);
        }

        results.values = filteredContents;
        results.count  = filteredContents.size();
        return results;
    }

    /**
     * Publish the filtering adapter list
     * @param constraint
     * @param results
     */
    @Override protected void publishResults(CharSequence constraint, FilterResults results) {
        mAdapterUsed.clear();
        mAdapterUsed.addAll((List<T>) results.values);

        if ( results.count == 0 ) {
            mAdapterUsed.notifyDataSetInvalidated();
        }
        else {
            mAdapterUsed.notifyDataSetChanged();
        }
    }

    // class properties
    private ArrayAdapter<T> mAdapterUsed;
    private List<T> mInternalList;
    private Method  mCompairMethod;
}

And afterwards, the only thing you need to do is to create the filter as a member class (possibly within the View’s “onCreate”) passing your adapter reference, your list, and the method to be called for filtering:

this.mFilter = new GenericFilter<MyObjectBean> (list, "getName", adapter);

The only thing missing now, is to override the “getFilter” method in the adapter class:

@Override public Filter getFilter () {
     return MyViewClass.this.mFilter;
}

All done! You should successfully filter your list – Of course, you should also implement your filter algorithm the best way that describes your need, the code bellow is just an example.. Hope it helped, take care.