为基本适配器搜索功能创建自定义过滤器

Question

我在列表视图中列出了用户安装的应用程序列表，我希望用户能够使用搜索栏功能（editText）进行搜索。 我在这里获得了我的Utilities类中定义的listview：

    public static List getInstalledApplication(Context c) {
    return c.getPackageManager().getInstalledApplications(PackageManager.GET_META_DATA);
}

然后我在Drag_and_Drop_App.java中显示listview：

package com.example.awesomefilebuilderwidget;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemClickListener;

public class Drag_and_Drop_App extends Activity {
private ListView mListAppInfo;
// Search EditText
EditText inputSearch;
AppInfoAdapter adapter;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // set layout for the main screen
    setContentView(R.layout.drag_and_drop_app);
    // import buttons
    Button btnLinkToFeedback = (Button) findViewById(R.id.btnLinkToFeedback);

    // Link to Feedback Screen
    btnLinkToFeedback.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),
                    Feedback.class);
            startActivity(i);
            finish();
        }
    });
    // create new adapter
    AppInfoAdapter adapter = new AppInfoAdapter(this, Utilities.getInstalledApplication(this), getPackageManager());
    // load list application
   mListAppInfo = (ListView)findViewById(R.id.lvApps);
    // set adapter to list view
    mListAppInfo.setAdapter(adapter);
    // search bar
    inputSearch = (EditText) findViewById(R.id.inputSearch);

    inputSearch.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {

            // When user changed the Text
            // Drag_and_Drop_App.this.adapter.getFilter().filter(cs);  
            Drag_and_Drop_App.this.adapter.getFilter().filter(cs);

        }

        @Override
        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub                          
        }
        });


    // implement event when an item on list view is selected
    mListAppInfo.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView parent, View view, int pos, long id) {
            // get the list adapter
            AppInfoAdapter appInfoAdapter = (AppInfoAdapter)parent.getAdapter();
            // get selected item on the list
            ApplicationInfo appInfo = (ApplicationInfo)appInfoAdapter.getItem(pos);
            // launch the selected application
            Utilities.launchApp(parent.getContext(), getPackageManager(), appInfo.packageName);
        }

    });

    // implement event when an item on list view is selected via long-click for drag and drop
    mListAppInfo.setOnItemLongClickListener(new OnItemLongClickListener(){

        @Override
        public boolean onItemLongClick(AdapterView parent, View view,
                int pos, long id) {
            // TODO Auto-generated method stub
            // get the list adapter
            AppInfoAdapter appInfoAdapter = (AppInfoAdapter)parent.getAdapter();
            // get selected item on the list
            ApplicationInfo appInfo = (ApplicationInfo)appInfoAdapter.getItem(pos);
            // launch the selected application
            Utilities.launchApp(parent.getContext(), getPackageManager(), appInfo.packageName);
            return true;
        }


    });
}
}

更具体地说，我在这里创建搜索功能：

       // create new adapter
    AppInfoAdapter adapter = new AppInfoAdapter(this, Utilities.getInstalledApplication(this), getPackageManager());
    // load list application
   mListAppInfo = (ListView)findViewById(R.id.lvApps);
    // set adapter to list view
    mListAppInfo.setAdapter(adapter);
    // search bar
    inputSearch = (EditText) findViewById(R.id.inputSearch);

    inputSearch.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {

            // When user changed the Text
            // Drag_and_Drop_App.this.adapter.getFilter().filter(cs);  
            Drag_and_Drop_App.this.adapter.getFilter().filter(cs);

        }

        @Override
        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub                          
        }
        });

我在这一行收到错误：

Drag_and_Drop_App.this.adapter.getFilter().filter(cs);

说＆＃34; getFilter（）＆＃34;在AppInfoAdapter中未定义：

package com.example.awesomefilebuilderwidget;

IMPORTS

public class AppInfoAdapter extends BaseAdapter {
private Context mContext;
private List mListAppInfo;
private PackageManager mPackManager;

public AppInfoAdapter(Context c, List list, PackageManager pm) {
    mContext = c;
    mListAppInfo = list;
    mPackManager = pm;
}

@Override
public int getCount() {
    return mListAppInfo.size();
}

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

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // get the selected entry
    ApplicationInfo entry = (ApplicationInfo) mListAppInfo.get(position);

    // reference to convertView
    View v = convertView;

    // inflate new layout if null
    if(v == null) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        v = inflater.inflate(R.layout.layout_appinfo, null);
    }

    // load controls from layout resources
    ImageView ivAppIcon = (ImageView)v.findViewById(R.id.ivIcon);
    TextView tvAppName = (TextView)v.findViewById(R.id.tvName);
    TextView tvPkgName = (TextView)v.findViewById(R.id.tvPack);

    // set data to display
    ivAppIcon.setImageDrawable(entry.loadIcon(mPackManager));
    tvAppName.setText(entry.loadLabel(mPackManager));
    tvPkgName.setText(entry.packageName);

    // return view
    return v;
}

@Override
public Filter getFilter() {
    // TODO Auto-generated method stub
    return filter;
}
}

所以，我环顾四周，注意到我必须创建自己的过滤器，所以我创建了filter_here类：

package com.example.awesomefilebuilderwidget;

import java.util.ArrayList;

import android.widget.Filter;

public class filter_here extends Filter{

@Override
protected FilterResults performFiltering(CharSequence constraint) {
    // TODO Auto-generated method stub

    FilterResults Result = new FilterResults();
    // if constraint is empty return the original names
    if(constraint.length() == 0 ){
        Result.values = Original_Names;
        Result.count = Original_Names.size();
        return Result;
    }

    ArrayList<String> Filtered_Names = new ArrayList<String>();
    String filterString = constraint.toString().toLowerCase();
    String filterableString;

    for(int i = 0; i<Original_Names.size(); i++){
        filterableString = Original_Names.get(i);
        if(filterableString.toLowerCase().contains(filterString)){
            Filtered_Names.add(filterableString);
        }
    }
    Result.values = Filtered_Names;
    Result.count = Filtered_Names.size();

    return Result;
}

@Override
protected void publishResults(CharSequence constraint,FilterResults results) {
    // TODO Auto-generated method stub
    Names = (ArrayList<String>) results.values;
    notifyDataSetChanged();
}

}

问题是这个类中的很多东西都是未定义的（我从另一个stackoverflow搜索得到了这个但是丢失了链接）。

我可以使用更好的过滤器类吗？