'Unexpexted Symbol &' und

Question

Diese Codezeile gibt mir Probleme in android Studios

if(musicSrv!=null && musicBound && musicSrv.isPng()) 

Der Code stammt aus diesem Tutorial 'Can not Symbol amp lösen' ich gefunden: Music Player

die vollständige Klasse Code:

package com.tunein.bryantyoung.tunein; 

import android.app.Activity; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import java.util.ArrayList; 
import java.util.Collections; 
import java.util.Comparator; 
import android.net.Uri; 
import android.content.ContentResolver; 
import android.database.Cursor; 
import android.widget.ListView; 
import android.os.IBinder; 
import android.content.ComponentName; 
import android.content.Context; 
import android.content.Intent; 
import android.content.ServiceConnection; 
import android.view.MenuItem; 
import android.view.View; 
import com.tunein.bryantyoung.tunein.MusicService.MusicBinder; 
import android.widget.MediaController.MediaPlayerControl; 

public class MainActivity extends Activity implements MediaPlayerControl { 
    private ArrayList<Song> songList; 
    private ListView songView; 
    private MusicController controller; 
    private MusicService musicSrv; 
    private Intent playIntent; 
    private boolean musicBound=false; 
    private boolean paused=false, playbackPaused=false; 

    /** 
    * Override methods 
    */ 
    @Override 
    public void start() { 
     musicSrv.go(); 
    } 

    @Override 
    public void pause() { 
     playbackPaused=true; 
     musicSrv.pausePlayer(); 
    } 

    @Override 
    public int getDuration() { 
     if(musicSrv!=null &amp;&amp; musicBound &amp;&amp; musicSrv.isPng()) 
      return musicSrv.getDur(); 
     else return 0; 
    } 

    @Override 
    public int getCurrentPosition() { 
     if(musicSrv!=null &amp;&amp; musicBound &amp;&amp; musicSrv.isPng()) 
     return musicSrv.getPosn(); 
     else return 0; 
    } 

    @Override 
    public void seekTo(int pos) { 
     musicSrv.seek(pos); 
    } 

    @Override 
    public boolean isPlaying() { 
     if(musicSrv!=null &amp;&amp; musicBound) 
      return musicSrv.isPng(); 
     return false; 
    } 

    @Override 
    public int getBufferPercentage() { 
     return 0; 
    } 

    @Override 
    public boolean canPause() { 
     return true; 
    } 

    @Override 
    public boolean canSeekBackward() { 
     return true; 
    } 

    @Override 
    public boolean canSeekForward() { 
     return true; 
    } 

    @Override 
    public int getAudioSessionId() { 
     return 0; 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     songView = (ListView)findViewById(R.id.song_list);//retrieves the list view using ID 
     songList = new ArrayList<Song>();//instantiates list view 
     getSongList(); 
     Collections.sort(songList, new Comparator<Song>() { 
      public int compare(Song a, Song b) { 
       return a.getTitle().compareTo(b.getTitle()); 
      } 
     }); 
     SongAdapter songAdt = new SongAdapter(this, songList); 
     songView.setAdapter(songAdt); 
     setController(); 
    } 

    @Override 
    protected void onStart() { 
     super.onStart(); 
     if(playIntent==null){ 
      playIntent = new Intent(this, MusicService.class); 
      bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE); 
      startService(playIntent); 
     } 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     //menu item selected 
     switch (item.getItemId()) { 
      case R.id.action_shuffle: 
       musicSrv.setShuffle(); 
       break; 
      case R.id.action_end: 
       stopService(playIntent); 
       musicSrv=null; 
       System.exit(0); 
       break; 
     } 
     return super.onOptionsItemSelected(item); 
    } 

    @Override 
    protected void onDestroy() { 
     stopService(playIntent); 
     musicSrv=null; 
     super.onDestroy(); 
    } 

    @Override 
    protected void onPause(){ 
     super.onPause(); 
     paused=true; 
    } 

    @Override 
    protected void onResume(){ 
     super.onResume(); 
     if(paused){ 
      setController(); 
      paused=false; 
     } 
    } 

    @Override 
    protected void onStop() { 
     controller.hide(); 
     super.onStop(); 
    } 


    /** 
    * Helpers 
    */ 

    //connect to the service 
    private ServiceConnection musicConnection = new ServiceConnection(){ 

     @Override 
     public void onServiceConnected(ComponentName name, IBinder service) { 
      MusicBinder binder = (MusicBinder)service; 
      //get service 
      musicSrv = binder.getService(); 
      //pass list 
      musicSrv.setList(songList); 
      musicBound = true; 
     } 

     @Override 
     public void onServiceDisconnected(ComponentName name) { 
      musicBound = false; 
     } 
    }; 

    public void getSongList() { 
     //retrieve song info 
     ContentResolver musicResolver = getContentResolver(); 
     Uri musicUri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; 
     Cursor musicCursor = musicResolver.query(musicUri, null, null, null, null); 

     //Iterate over the results 
     if(musicCursor!=null && musicCursor.moveToFirst()){ 
      //get columns 
      int titleColumn = musicCursor.getColumnIndex 
        (android.provider.MediaStore.Audio.Media.TITLE); 
      int idColumn = musicCursor.getColumnIndex 
        (android.provider.MediaStore.Audio.Media._ID); 
      int artistColumn = musicCursor.getColumnIndex 
        (android.provider.MediaStore.Audio.Media.ARTIST); 
      //add songs to list 
      do { 
       long thisId = musicCursor.getLong(idColumn); 
       String thisTitle = musicCursor.getString(titleColumn); 
       String thisArtist = musicCursor.getString(artistColumn); 
       songList.add(new Song(thisId, thisTitle, thisArtist)); 
      } 
      while (musicCursor.moveToNext()); 
     } 
    } 

    public void songPicked(View view){ 
     musicSrv.setSong(Integer.parseInt(view.getTag().toString())); 
     musicSrv.playSong(); 
     if(playbackPaused){ 
      setController(); 
      playbackPaused=false; 
     } 
     controller.show(0); 
    } 

    private void setController(){ 
     //set the controller up 
     controller = new MusicController(this); 

     //Click listeners for next and Prev 
     controller.setPrevNextListeners(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       playNext(); 
      } 
     }, new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       playPrev(); 
      } 
     }); 

     controller.setMediaPlayer(this); 
     controller.setAnchorView(findViewById(R.id.song_list)); 
     controller.setEnabled(true); 
    } 

    //play next 
    private void playNext(){ 
     musicSrv.playNext(); 
     if(playbackPaused){ 
      setController(); 
      playbackPaused=false; 
     } 
     controller.show(0); 
    } 

    //play prev 
    private void playPrev(){ 
     musicSrv.playPrev(); 
     if(playbackPaused){ 
      setController(); 
      playbackPaused=false; 
     } 
     controller.show(0); 
    } 

} 

der Kodex für einen Musik-Player die Haupttätigkeit ist ca. die Zeile, die mit Probleme im, ist wohl eine bedingte Anweisung, aber ich meine selbst bin nicht Sicher wie es funktioniert Ich habe vorher keine ähnlichen Aussagen gemacht.

Answer 1

Die & ist eine Web-Codierung für das Symbol &.

Ihr Code wird funktionieren, wenn Sie alle &-& ändern, so wird der Code wie:

musicSrv!=null && musicBound 

Statt:

musicSrv!=null && musicBound 

Hoffe, es hilft!