MP3 songs do not play in media player

Question

I am trying out below code here is the MainActivity.java

import java.io.File;
import java.util.ArrayList;

import javax.crypto.spec.PSource;

import android.R.string;
import android.support.v7.app.ActionBarActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterViewFlipper;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

    ListView lv;
    String[] items;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv =  (ListView) findViewById(R.id.lvPlaylist);
        final ArrayList<File> mySongs = findSongs(Environment.getExternalStorageDirectory());
        items =  new String[mySongs.size () ];
        for (int i = 0; i < mySongs.size(); i++) {
            //toast(mySongs.get(i).getName().toString());
            items[i] = mySongs.get(i).getName().toString();
        }

        ArrayAdapter<String> adp = new ArrayAdapter<String>(getApplicationContext(),R.layout.list_item,R.id.textView1,items);
        lv.setAdapter(adp);
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // TODO Auto-generated method stub
                startActivity(new Intent(getApplicationContext(), player.class).putExtra("pos", position).putExtra("songlist",mySongs));
            }
        });
    }

    public ArrayList<File> findSongs(File root){
        ArrayList al = new ArrayList<File>();
        File[] files = root.listFiles();
        for(File singleFile : files){
            if (singleFile.isDirectory()&& !singleFile.isHidden()) {
                al.addAll(findSongs(singleFile));

            }
            else {
                if (singleFile.getName().endsWith(".mp3") || singleFile.getName().endsWith(".wav")) {
                    al.add(singleFile);
                }
            }
        }
        return al;
    }

    public void toast(String text) {
        Toast.makeText(getApplicationContext(), text, Toast.LENGTH_SHORT).show();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }



    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

above code gives me a list of mp3 files when we click on one of the songs it takes to player.ja and songs are played

and player.java

import java.io.File;
import java.util.ArrayList;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter.ViewBinder;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.SeekBar;

public class player extends ActionBarActivity implements View.OnClickListener{
    static MediaPlayer mp;
    ArrayList<File> mySongs;
    int position;
    Uri u;

    SeekBar sb;
    Button btPv, btFB,btplay,btFF, btNxt;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_player);
        btFB = (Button) findViewById(R.id.btFB);
        btPv = (Button) findViewById(R.id.btPv);
        btplay = (Button) findViewById(R.id.btplay);
        btFF = (Button) findViewById(R.id.btFF);
        btNxt = (Button) findViewById(R.id.btNxt);

        btFB.setOnClickListener(this) ;
        btPv.setOnClickListener(this);
        btplay.setOnClickListener(this);
        btFF.setOnClickListener(this);
        btNxt.setOnClickListener(this);
//      
        if(mp != null)
        {
            mp.stop();
            mp.release();

        }


        Intent i = getIntent();
        Bundle  b = i.getExtras();
        mySongs = (ArrayList) b.getParcelableArrayList("songlist");
        position = b.getInt("pos", 0);
        u = Uri.parse(mySongs.get(position).toString());
        mp = MediaPlayer.create(getApplicationContext(), u).start();
        mp.start();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    @Override
    public void onClick(View v)
    {
        int id = v.getId();
        switch (id) {
        case R.id.btplay:
            if(mp.isPlaying())
            {btplay.setText("play"); 
                mp.pause(); 
            }
            else
            {   btplay.setText("play"); 
                mp.start();
            }
            break;
        case R.id.btFF:
            mp.seekTo(mp.getCurrentPosition()+ 5000);
            break;
        case R.id.btFB:
            mp.seekTo(mp.getCurrentPosition()- 5000);
            break;
        case R.id.btNxt:
            mp.stop();
            mp.release();
            position = (position+1)%mySongs.size();
            u = Uri.parse(mySongs.get(position).toString());
            mp = MediaPlayer.create(getApplicationContext(), u);
            mp.start();
            break;
        case R.id.btPv :
            mp.stop();
            mp.release();
            // Important
            position =  (position-1<0) ?  mySongs.size()-1: position-1;
            /*if(position-1 < 0)

            {
                position = mySongs.size()-1;

            }
            else
            {
                position= position-1;
            }*/
            u = Uri.parse(mySongs.get(position).toString());
            mp = MediaPlayer.create(getApplicationContext(), u);
            mp.start();
        default:
            break;
        }
    }

}

While the above code works perfectly fine for few songs which are mp3 but it does not work for other songs which are also mp3 . I have tried this on an actual device the app would just crash if the song has some problem the mp3 files which give me problems work perfectly on other media players and even the default android media player

What exactly could be the issue?

Answer 1

您需要先调用mediaPlayer.prepare()或mediaPlayer.prepareAsync()然后再调用mediaPlayer.start() ，如果应用程序崩溃，请发布日志，以便我们知道问题所在。