Custom filtering in Android using ArrayAdapter
I'm trying to filter my ListView which is populated with this ArrayAdapter:
package me.alxandr.android.mymir.adapters;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import me.alxandr.android.mymir.R;
import me.alxandr.android.mymir.model.Manga;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Filter;
import android.widget.SectionIndexer;
import android.widget.TextView;
public class MangaListAdapter extends ArrayAdapter<Manga> implements SectionIndexer
{
public ArrayList<Manga> items;
public ArrayList<Manga> filtered;
private Context context;
private HashMap<String, Integer> alphaIndexer;
private String[] sections = new String[0];
private Filter filter;
private boolean enableSections;
public MangaListAdapter(Context context, int textViewResourceId, ArrayList<Manga> items, boolean enableSections)
{
super(context, textViewResourceId, items);
this.filtered = items;
this.items = filtered;
this.context = context;
this.filter = new MangaNameFilter();
this.enableSections = enableSections;
if(enableSections)
{
alphaIndexer = new HashMap<String, Integer>();
for(int i = items.size() - 1; i >= 0; i--)
{
Manga element = items.get(i);
String firstChar = element.getName().substring(0, 1).toUpperCase();
if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A')
firstChar = "@";
alphaIndexer.put(firstChar, i);
}
Set<String> keys = alphaIndexer.keySet();
Iterator<String> it = keys.iterator();
ArrayList<String> keyList = new ArrayList<String>();
while(it.hasNext())
keyList.add(it.next());
Collections.sort(keyList);
sections = new String[keyList.size()];
keyList.toArray(sections);
}
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
View v = convertView;
if(v == null)
{
LayoutInflater vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.mangarow, null);
}
Manga o = items.get(position);
if(o != null)
{
TextView tt = (TextView) v.findViewById(R.id.MangaRow_MangaName);
TextView bt = (TextView) v.findViewById(R.id.MangaRow_MangaExtra);
if(tt != null)
tt.setText(o.getName());
if(bt != null)
bt.setText(o.getLastUpdated() + " - " + o.getLatestChapter());
if(enableSections && getSectionForPosition(position) != getSectionForPosition(position + 1))
{
TextView h = (TextView) v.findViewById(R.id.MangaRow_Header);
h.setText(sections[getSectionForPosition(position)]);
h.setVisibility(View.VISIBLE);
}
else
{
TextView h = (TextView) v.findViewById(R.id.MangaRow_Header);
h.setVisibility(View.GONE);
}
}
return v;
}
@Override
public void notifyDataSetInvalidated()
{
if(enableSections)
{
for (int i = items.size() - 1; i >= 0; i--)
{
Manga element = items.get(i);
String firstChar = element.getName().substring(0, 1).toUpperCase();
if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A')
firstChar = "@";
alphaIndexer.put(firstChar, i);
}
Set<String> keys = alphaIndexer.keySet();
Iterator<String> it = keys.iterator();
ArrayList<String> keyList = new ArrayList<String>();
while (it.hasNext())
{
keyList.add(it.next());
}
Collections.sort(keyList);
sections = new String[keyList.size()];
keyList.toArray(sections);
super.notifyDataSetInvalidated();
}
}
public int getPositionForSection(int section)
{
if(!enableSections) return 0;
String letter = sections[section];
return alphaIndexer.get(letter);
}
public int getSectionForPosition(int position)
{
if(!enableSections) return 0;
int prevIndex = 0;
for(int i = 0; i < sections.length; i++)
{
if(getPositionForSection(i) > position && prevIndex <= position)
{
prevIndex = i;
break;
}
prevIndex = i;
}
return prevIndex;
}
public Object[] getSections()
{
return sections;
}
@Override
public Filter getFilter()
{
if(filter == null)
filter = new MangaNameFilter();
return filter;
}
private class MangaNameFilter extends Filter
{
@Override
protected FilterResults performFiltering(CharSequence constraint) {
// NOTE: this function is *always* called from a background thread, and
// not the UI thread.
constraint = constraint.toString().toLowerCase();
FilterResults result = new FilterResults();
if(constraint != null && constraint.toString().length() > 0)
{
ArrayList<Manga> filt = new ArrayList<Manga>();
ArrayList<Manga> lItems = new ArrayList<Manga>();
synchronized (items)
{
Collections.copy(lItems, items);
}
for(int i = 0, l = lItems.size(); i < l; i++)
{
Manga m = lItems.get(i);
if(m.getName().toLowerCase().contains(constraint))
filt.add(m);
}
result.count = filt.size();
result.values = filt;
}
else
{
synchronized(items)
{
result.values = items;
result.count = items.size();
}
}
return result;
}
@SuppressWarnings("unchecked")
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
// NOTE: this function is *always* called from the UI thread.
filtered = (ArrayList<Manga>)results.values;
notifyDataSetChanged();
}
}
}
However, when I call filter('test') on the filter nothing happens at all (or the background-thread is run, but the list isn't filtered as far as the user conserns). How can I fix this?
Answer
This fixed my problem. I'm not certain it's the best solution, but it works. My project's open-source, so feel free to use any of the code here should it prove usefull :-).
package me.alxandr.android.mymir.adapters;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import me.alxandr.android.mymir.R;
import me.alxandr.android.mymir.model.Manga;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Filter;
import android.widget.SectionIndexer;
import android.widget.TextView;
public class MangaListAdapter extends ArrayAdapter<Manga> implements SectionIndexer
{
public ArrayList<Manga> items;
public ArrayList<Manga> filtered;
private Context context;
private HashMap<String, Integer> alphaIndexer;
private String[] sections = new String[0];
private Filter filter;
private boolean enableSections;
public Manga getByPosition(int position)
{
return items.get(position);
}
public MangaListAdapter(Context context, int textViewResourceId, ArrayList<Manga> items, boolean enableSections)
{
super(context, textViewResourceId, items);
this.filtered = items;
this.items = ArrayList<Manga> items.clone();
this.context = context;
this.filter = new MangaNameFilter();
this.enableSections = enableSections;
if(enableSections)
{
alphaIndexer = new HashMap<String, Integer>();
for(int i = items.size() - 1; i >= 0; i--)
{
Manga element = items.get(i);
String firstChar = element.getName().substring(0, 1).toUpperCase();
if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A')
firstChar = "@";
alphaIndexer.put(firstChar, i);
}
Set<String> keys = alphaIndexer.keySet();
Iterator<String> it = keys.iterator();
ArrayList<String> keyList = new ArrayList<String>();
while(it.hasNext())
keyList.add(it.next());
Collections.sort(keyList);
sections = new String[keyList.size()];
keyList.toArray(sections);
}
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
View v = convertView;
if(v == null)
{
LayoutInflater vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.mangarow, null);
}
Manga o = filtered.get(position);
if(o != null)
{
TextView tt = (TextView) v.findViewById(R.id.MangaRow_MangaName);
TextView bt = (TextView) v.findViewById(R.id.MangaRow_MangaExtra);
if(tt != null)
tt.setText(o.getName());
if(bt != null)
bt.setText(o.getLastUpdated() + " - " + o.getLatestChapter());
if(enableSections && getSectionForPosition(position) != getSectionForPosition(position + 1))
{
TextView h = (TextView) v.findViewById(R.id.MangaRow_Header);
h.setText(sections[getSectionForPosition(position)]);
h.setVisibility(View.VISIBLE);
}
else
{
TextView h = (TextView) v.findViewById(R.id.MangaRow_Header);
h.setVisibility(View.GONE);
}
}
return v;
}
@Override
public void notifyDataSetInvalidated()
{
if(enableSections)
{
for (int i = items.size() - 1; i >= 0; i--)
{
Manga element = items.get(i);
String firstChar = element.getName().substring(0, 1).toUpperCase();
if(firstChar.charAt(0) > 'Z' || firstChar.charAt(0) < 'A')
firstChar = "@";
alphaIndexer.put(firstChar, i);
}
Set<String> keys = alphaIndexer.keySet();
Iterator<String> it = keys.iterator();
ArrayList<String> keyList = new ArrayList<String>();
while (it.hasNext())
{
keyList.add(it.next());
}
Collections.sort(keyList);
sections = new String[keyList.size()];
keyList.toArray(sections);
super.notifyDataSetInvalidated();
}
}
public int getPositionForSection(int section)
{
if(!enableSections) return 0;
String letter = sections[section];
return alphaIndexer.get(letter);
}
public int getSectionForPosition(int position)
{
if(!enableSections) return 0;
int prevIndex = 0;
for(int i = 0; i < sections.length; i++)
{
if(getPositionForSection(i) > position && prevIndex <= position)
{
prevIndex = i;
break;
}
prevIndex = i;
}
return prevIndex;
}
public Object[] getSections()
{
return sections;
}
@Override
public Filter getFilter()
{
if(filter == null)
filter = new MangaNameFilter();
return filter;
}
private class MangaNameFilter extends Filter
{
@Override
protected FilterResults performFiltering(CharSequence constraint) {
// NOTE: this function is *always* called from a background thread, and
// not the UI thread.
constraint = constraint.toString().toLowerCase();
FilterResults result = new FilterResults();
if(constraint != null && constraint.toString().length() > 0)
{
ArrayList<Manga> filt = new ArrayList<Manga>();
ArrayList<Manga> lItems = new ArrayList<Manga>();
synchronized (this)
{
lItems.addAll(items);
}
for(int i = 0, l = lItems.size(); i < l; i++)
{
Manga m = lItems.get(i);
if(m.getName().toLowerCase().contains(constraint))
filt.add(m);
}
result.count = filt.size();
result.values = filt;
}
else
{
synchronized(this)
{
result.values = items;
result.count = items.size();
}
}
return result;
}
@SuppressWarnings("unchecked")
@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
// NOTE: this function is *always* called from the UI thread.
filtered = (ArrayList<Manga>)results.values;
notifyDataSetChanged();
clear();
for(int i = 0, l = filtered.size(); i < l; i++)
add(filtered.get(i));
notifyDataSetInvalidated();
}
}
}