java - 在 ListView 中单击的项目位置错误

Question

我是 android studio 编程的新手，在尝试从列表 fragment 获取 ListView 中单击的项目的位置时遇到了一些麻烦。

问题是，我有一个主要 Activity ，其中有一个查看寻呼机，其中一个页面是歌曲列表。我想要的是获取此列表中所选歌曲的位置。我尝试在 mi List fragment 中实现点击处理程序，但它总是显示下一个错误:“无法在父级或祖先上下文中找到方法”(已尝试更改函数的名称和 xml 文件中的名称)，所以我尝试了处理 MainActivity 中的点击事件，它实际上有效，但是当我尝试获取位置时，它总是返回 -1

这些是我的相关文件:MainActivity.java

package com.example.marino.practica2marinoperezsegura;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.design.widget.TabLayout;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.ListFragment;
import android.support.v4.view.GravityCompat;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;

import java.io.IOException;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity  implements NavigationView.OnNavigationItemSelectedListener, View.OnClickListener  {
    private static final int REQ_PERMISSION = 1543;
    private boolean changeTheme = false;
    private ArrayList<Uri> paths = new ArrayList<Uri>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, REQ_PERMISSION);
            return;
        }

        SQLiteOpenHelper songDbHelper = new SongsDataHelper(this) ;
        SQLiteDatabase db = songDbHelper.getReadableDatabase();

        Cursor path = db.query("SONGS",
                new String[] {"PATH"},
                null,
                null,
                null, null, null);

        if (path.moveToFirst()) {
            do {
                paths.add(Uri.parse(path.getString(0)));
            } while(path.moveToNext());
        }

        SharedPref sharedPref;
        sharedPref = new SharedPref(this);
        if(sharedPref.loadNightModeState() == true){
            changeTheme = true;
            setTheme(R.style.SecondActivityTheme);
        }
        else {
            setTheme(R.style.AppTheme);
        }


        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        CategoriesPagerAdapter adapter = new CategoriesPagerAdapter(
                getSupportFragmentManager(), this);
        ViewPager pager = findViewById(R.id.viewpager);
        pager.setAdapter(adapter);

        android.support.v7.widget.Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
        tabLayout.setupWithViewPager(pager);

        DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawerlayoutMain);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this,
                drawerLayout,
                toolbar,
                0,
                0
        );
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.navigationdrawer_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    @Override
    public void onBackPressed()
    {
        DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawerlayoutMain);
        if (drawerLayout.isDrawerOpen(GravityCompat.START))
        {
            drawerLayout.closeDrawer(GravityCompat.START);
        }
        else
        {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
        int id = menuItem.getItemId();
        switch (id)
        {
            case R.id.navigation_lists :
                Intent lists = new Intent(this, ReproductionListActivity.class);
                startActivity(lists);
                break;
            case R.id.navigation_library :
                Intent library = new Intent(this, MainActivity.class);
                startActivity(library);
                break;
            case R.id.navigation_options :
                Intent options = new Intent(this, OptionsActivity.class);
                startActivity(options);
                break;
        }
        DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawerlayoutMain);
        drawerLayout.closeDrawer(GravityCompat.START);
        return true;
    }

    //Here is where the event works but the int i gets always -1 value
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.play_song: {
                View parentRow = (View) v.getParent().getParent().getParent();
                ListView listView = (ListView) parentRow.getParent();
                if (!MediaPlayerManager.isInitialized()) {  //Never used media player? select file to play
                    try {
                        int i = listView.getSelectedItemPosition();
                        MediaPlayerManager.startNewTrack(this, paths.get(i));
                    }catch (IOException e) {
                        e.printStackTrace();
                    }
                } else if (MediaPlayerManager.isPlaying()) {
                    MediaPlayerManager.pauseMusic();
                } else {
                    MediaPlayerManager.startPlaying();
                }
                break;
            }
        }
    }


}

歌曲.java

package com.example.marino.practica2marinoperezsegura;

import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.net.Uri;
import android.os.Bundle;
import android.os.Debug;
import android.support.v4.app.ListFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;

import java.util.ArrayList;

public class Songs extends ListFragment{
    private boolean played = false;
    private ArrayList<Uri> paths = new ArrayList<Uri>();

    public Songs() {
// Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        SQLiteOpenHelper songDbHelper = new SongsDataHelper(getContext()) ;
        SQLiteDatabase db = songDbHelper.getReadableDatabase();
        //((SongsDataHelper) songDbHelper).addVideogame(db, "Pruebita","AJARL");
        Cursor path = db.query("SONGS",
                new String[] {"PATH"},
                null,
                null,
                null, null, null);

        /*if (path.moveToFirst()) {
            do {
                paths.add((path.get(0));
            } while(path.moveToNext());
        }*/

        Cursor cursor = db.query("SONGS",
                new String[] {"_id", "NAME", "DURATION"},
                null,
                null,
                null, null, null);

        String[] columns = new String[]{"NAME", "DURATION"};
        int[] to = new int[] {R.id.song_title, R.id.song_duration};


        SimpleCursorAdapter listAdapter = new SimpleCursorAdapter(
                getContext(),
                R.layout.songs_list,
                cursor,
                columns,
                to,
                0);
        setListAdapter(listAdapter);
// Inflate the layout for this fragment
        return super.onCreateView(inflater, container, savedInstanceState);
    }

    public void onListItemclick(ListView l, View view, int position, long id){
        ViewGroup viewGroup= (ViewGroup)view;
        ImageButton selectedSong = (ImageButton)viewGroup.findViewById(R.id.play_song);
        Log.e("Name :" + position, " Album :");

    }

  //Here is where it shows me the "Could not find method in parent ancestor context" error

 /* @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.play_song: {
                Log.e("Name :", " Album :");
                break;
                if (!MediaPlayerManager.isInitialized()) {  //Never used media player? select file to play
                    MediaPlayerManager.startNewTrack(this, paths.get(0));
                } else if (this.played) {
                    MediaPlayerManager.pauseMusic();
                } else {
                    MediaPlayerManager.startPlaying();
                }
                break;
            }
        }
    }*/
}

类别Pageradapter.java

package com.example.marino.practica2marinoperezsegura;

import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

public class CategoriesPagerAdapter  extends FragmentPagerAdapter {
    private Context m_context;
    public CategoriesPagerAdapter (FragmentManager fragmentManager, Context context)
    {
        super(fragmentManager);
        m_context = context;
    }
    @Override
    public int getCount ()
    {
        return 2;
    }

    @Override
    public Fragment getItem (int position)
    {
        switch (position)
        {
            case 0:
                return new Albums();
            case 1:
                return new Songs();
        }
        return null;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position)
        {
            case 0:
                return m_context.getResources().getText(R.string.home_tab);
            case 1:
                return m_context.getResources().getText(R.string.songs_tab);
        }
        return null;
    }

}

我在此代码中期望的是获取所选项目的位置数并将其保存在 i 变量中，而不是获取 -1

感谢您的宝贵时间。

Answer 1

根据您的代码，您正在检查“Activity ”上的点击事件。如果我假设您在 onClick() 内获取点击事件

然后您可以通过添加位置元数据来查看来解决问题。喜欢

case R.id.play_song:
                    int position = (int)view.getTag();
                    //and use this position for MediaPlayer

现在如何设置这些元数据来查看。

为此，您需要通过扩展它来创建您自己的 SimpleCursorAdapter 类版本像下面这样

public class MyAdapter extends SimpleCursorAdapter {

    public MyAdapter(Context context, int layout, Cursor c, String[] from,
                           int[] to, int flags) {
       super(context, layout, c, from,to,flags);
    }

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
       View view = super.getView(position, convertView, parent);
       //Here we are adding meta data which is position in our case
       view.findViewById(R.id.play_song).setTag(position);
       return view;
    }
}

现在在您的 Songs fragment 中使用 SimpleCursorAdapter 的扩展版本。