java - 如何实现适配器并过滤结果？

Question

我正在尝试开发一个应用程序，但我很困惑这个问题。我需要过滤一个列表(由图书馆组成)，以显示它们是否在早上开放。

我为每个库都有一个类，其中有两个全局 boolean 变量，称为“isMattina”(isMorning)和“isPomeriggio”(“isAfternoon”)。

我遵循了互联网上的一些指南，现在我的代码如下所示:

package com.matteocunsolo.apposto;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.ListView;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.Toast;

import com.matteocunsolo.apposto.IOFromFile;

public class BiblioList extends Activity {
    private Spinner spinner1;
    public static Context context;
    public int length;
    public ArrayList<String> list;
    private Button btnSubmit;
    public boolean[] elencoOrari = TimeBooleanArray.create();
    public Filter mioFiltro;
    public StableArrayAdapter adapter;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.lista);
        setContext();
        addListenerOnButton();
        addListenerOnSpinnerItemSelection();
        final ListView listview = (ListView) findViewById(R.id.listview);
        String filePath = Environment.getExternalStorageDirectory() + "/ApPosto/";
        //InputStream is = getResources().openRawResource(R.raw.elenco_titoli);
        String[] values = IOFromFile.readTextFile(filePath + "elenco_Titoli.txt");
        length = values.length;
        list = new ArrayList<String>();
        for (int i = 0; i < values.length; ++i) {
            list.add(values[i]);
        }
        adapter = new StableArrayAdapter(this, android.R.layout.simple_list_item_1, list);
        listview.setAdapter(adapter);
        Toast.makeText(getApplicationContext(), Integer.toString(list.size()), Toast.LENGTH_SHORT).show();
        listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, final View view, int position, long id) {
                if(position == 0) {
                Intent i = new Intent(BiblioList.this, InfoBiblioteca1.class); 
                startActivity(i);
                }
            else if(position == 1) {
                Intent i = new Intent( BiblioList.this, InfoBiblioteca2.class); 
                startActivity(i);
                }
            else if(position == 4) {
                Intent i = new Intent( BiblioList.this, InfoBiblioteca3.class); 
                startActivity(i);
            }
            else if(position == 5) {
                Intent i = new Intent( BiblioList.this, InfoBiblioteca4.class); 
                startActivity(i);
            }
            }
        });
    }

    public void setContext() {
        context = getApplicationContext();
    }

    public void addListenerOnSpinnerItemSelection() {
        spinner1 = (Spinner) findViewById(R.id.spinner1);
        spinner1.setOnItemSelectedListener(new CustomOnItemSelectedListener());
    }

    public void addListenerOnButton() {
        spinner1 = (Spinner) findViewById(R.id.spinner1);
        btnSubmit = (Button) findViewById(R.id.button1);     
        btnSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(spinner1.getSelectedItem().toString() == null)
                    Toast.makeText(BiblioList.this, "adapter NULL", Toast.LENGTH_SHORT).show();
                else 
                    adapter.getFilter().filter(spinner1.getSelectedItem().toString());
              }

            });
        }


    private class StableArrayAdapter extends ArrayAdapter<String> implements Filterable {
        HashMap<String, Integer> mIdMap = new HashMap<String, Integer>();

        public StableArrayAdapter(Context context, int textViewResourceId, List<String> objects) {
            super(context, textViewResourceId, objects);
            for (int i = 0; i < objects.size(); ++i) {
                mIdMap.put(objects.get(i), i);
            }
        }

        @Override
        public long getItemId(int position) {
          String item = getItem(position);
          return mIdMap.get(item);
        }

        @Override
        public boolean hasStableIds() {
          return true;
        }
        @Override 
        public Filter getFilter() { 
            if (mioFiltro == null) 
                mioFiltro = new MyFilter(); 
            return mioFiltro; 
        }
    }


    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.returntomap, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.change_layout){ 
            Intent i = new Intent(BiblioList.this, LaunchActivity.class);
            overridePendingTransition(R.anim.anim_in, R.anim.anim_out);
            startActivity(i);
        }

        return true;
    } 

    private class MyFilter extends Filter {

        @Override 
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults(); 
            // We implement here the filter logic 
            if (constraint == null || constraint.length() == 0) { 
                // No filter implemented we return all the list 
                results.values = list; 
                results.count = list.size(); 
            } else { 
                // We perform filtering operation 
                List<String> nlist = new ArrayList<String>();
                if(constraint.equals("Mattina")) {
                    for(int i = 0; i < 4; i = i+2) {
                        if(elencoOrari[i])
                            nlist.add(list.get(i));
                    }
                }
                if(constraint.equals("Pomeriggio")) {
                    for(int i = 1; i < 4; i = i+2) {
                        if(elencoOrari[i])
                            nlist.add(list.get(i));
                    }
                }

                results.values = nlist; 
                results.count = nlist.size(); 
            } return results;
        } 
        @SuppressWarnings("unchecked")
        @Override 
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results.count == 0) 
                adapter.notifyDataSetInvalidated(); 
            else { 
                list = (ArrayList<String>) results.values; 
                adapter.notifyDataSetChanged(); 
            } 
        } 
    }

}

这是 TimeBooleanArray.java:

package com.matteocunsolo.apposto;

public class TimeBooleanArray {

    public static boolean[] create() {
        boolean[] elencoOrari = new boolean[4];
        for(int i = 0; i<elencoOrari.length; i++) {
            elencoOrari[i] = false;
        }
        if(InfoBiblioteca1.isMattina)
            elencoOrari[0] = true;
        if(InfoBiblioteca1.isPomeriggio)
            elencoOrari[1] = true;
        if(InfoBiblioteca2.isMattina)
            elencoOrari[2] = true;
        if(InfoBiblioteca2.isPomeriggio)
            elencoOrari[3] = true;

        return elencoOrari;
    }
}

运行此应用程序并单击“Filtra”按钮，我没有从 LogCat 中收到任何错误，但什么也没有发生。该列表保持不变，具有相同的 6 个条目，而不是具有正确 boolean 值的 1 个条目。

比你们都提前!

Answer 1

您在 publishResults 中的代码实际上从未更改适配器存储的内容。适配器保留自己对列表的引用。您可以使用 clear() 和 addAll() 更改列表的内容。

@Override  
protected void publishResults(CharSequence constraint, FilterResults results) {
    if (results.count == 0) 
        adapter.notifyDataSetInvalidated(); 
    else {  
        adapter.clear();
        adapter.addAll(results.values); 
        adapter.notifyDataSetChanged();
    }  
}