使用gson保存數據和媒體播放器服務時出現錯誤

我正在關注用於音頻播放器的this教程。我能夠播放服務中的歌曲。但是當我嘗試使用gson保存歌曲並將數組列表發送到服務中，但是當我與錯誤的列表項單擊該應用程序崩潰的服務使用gson保存數據和媒體播放器服務時出現錯誤

FATAL EXCEPTION: main 
       Process: com.example.neelay.level95, PID: 15133 
       java.lang.RuntimeException: Unable to start service [email protected] with Intent { cmp=com.example.neelay.level95/.MediaPlayerService }: java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args 
        at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3034) 
        at android.app.ActivityThread.access$2200(ActivityThread.java:153) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5441) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628) 
       Caused by: java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args 
        at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:111) 
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:210) 
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:129) 
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:220) 
        at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41) 
        at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:82) 
        at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61) 
        at com.google.gson.Gson.fromJson(Gson.java:887) 
        at com.google.gson.Gson.fromJson(Gson.java:852) 
        at com.google.gson.Gson.fromJson(Gson.java:801) 
        at com.example.neelay.level95.StorageUtil.loadAudio(StorageUtil.java:42) 
        at com.example.neelay.level95.MediaPlayerService.onStartCommand(MediaPlayerService.java:106) 
        at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3017) 
        at android.app.ActivityThread.access$2200(ActivityThread.java:153)  
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449)  
        at android.os.Handler.dispatchMessage(Handler.java:102)  
        at android.os.Looper.loop(Looper.java:148)  
        at android.app.ActivityThread.main(ActivityThread.java:5441)  
        at java.lang.reflect.Method.invoke(Native Method)  
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)  
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)  
       Caused by: java.lang.InstantiationException: Can't instantiate abstract class android.net.Uri 
        at java.lang.reflect.Constructor.newInstance(Native Method) 
        at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:108) 
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:210)  
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:129)  
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:220)  
        at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41)  
        at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:82)  
        at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)  
        at com.google.gson.Gson.fromJson(Gson.java:887)  
        at com.google.gson.Gson.fromJson(Gson.java:852)  
        at com.google.gson.Gson.fromJson(Gson.java:801)  
        at com.example.neelay.level95.StorageUtil.loadAudio(StorageUtil.java:42)  
        at com.example.neelay.level95.MediaPlayerService.onStartCommand(MediaPlayerService.java:106)  
        at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3017)  
        at android.app.ActivityThread.access$2200(ActivityThread.java:153)  
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449)  
        at android.os.Handler.dispatchMessage(Handler.java:102)  
        at android.os.Looper.loop(Looper.java:148)  
        at android.app.ActivityThread.main(ActivityThread.java:5441)  
        at java.lang.reflect.Method.invoke(Native Method)  
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)  
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)

錯誤在那裏我得到錯誤

@Override 
public int onStartCommand(Intent intent, int flags, int startId) { 
    try { 

     //Load data from SharedPreferences 
     StorageUtil storage = new StorageUtil(getApplicationContext()); 
     audioList = storage.loadAudio(); 
     audioIndex = storage.loadAudioIndex(); 

     if (audioIndex != -1 && audioIndex < audioList.size()) { 
      //index is in a valid range 
      activeAudio = audioList.get(audioIndex); 
     } else { 
      stopSelf(); 
     } 
    } catch (NullPointerException e) { 
     stopSelf(); 
    } 

    //Request audio focus 
    if (requestAudioFocus() == false) { 
     //Could not gain focus 
     stopSelf(); 
    } 

    if (mediaSessionManager == null) { 
     try { 
      initMediaSession(); 
      initMediaPlayer(); 
     } catch (RemoteException e) { 
      e.printStackTrace(); 
      stopSelf(); 
     } 
     buildNotification(PlaybackStatus.PLAYING); 
    } 

    //Handle Intent action from MediaSession.TransportControls 
    handleIncomingActions(intent); 
    return super.onStartCommand(intent, flags, startId); 
}

錯誤songutil課堂，它顯示錯誤

public ArrayList<Songfileinfo> loadAudio() { 
    preferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE); 
    Gson gson = new Gson(); 
    String json = preferences.getString("audioArrayList", null); 
    Type type = new TypeToken<ArrayList<Songfileinfo>>() { 
    }.getType(); 
    return gson.fromJson(json, type); 
}

我只能知道我在管線106 audioList = storage.loadAudio();並在第41行 return gson.fromJson(json, type); songutil類得到錯誤的服務類，但我怎麼能解決這個問題的任何幫助將是helpfull.Now我能播放歌曲，當我從songfileinfo刪除一些代碼這裏是代碼

public class Songfileinfo implements Serializable { 
private String title,album,artist,file_uri;

// private Uri album_art; //私人長期持續時間;

public Songfileinfo(String data, String title, String album, String artist) { 
    this.file_uri = data; 
    this.title = title; 
    this.album = album; 
    this.artist = artist; 
} 

public Songfileinfo() { 

} 

public String getTitle() { 
    return title; 
} 

public void setTitle(String title) { 
    this.title = title; 
} 

public String getAlbum() { 
    return album; 
} 

public void setAlbum(String album) { 
    this.album = album; 
} 

public String getArtist() { 
    return artist; 
} 

public void setArtist(String artist) { 
    this.artist = artist; 
} 

public String getFile_uri() { 
    return file_uri; 
} 

public void setFile_uri(String file_uri) { 
    this.file_uri = file_uri; 
}

}

但是當我添加的代碼THES lises它還是會被撞壞

private Uri album_art; 
private long duration; 
public Uri getAlbum_art() { 
    return album_art; 
} 

public void setAlbum_art(Uri album_art) { 
    this.album_art = album_art; 
} 

public long getDuration() { 
    return duration; 
} 

public void setDuration(long duration) { 
    this.duration = duration; 
}

Ÿ是越來越墜毀我在構造函數中添加它也是任何理由。

來源

2016-12-31 Neelay Srivastava

基本上，Gson使用java反射從json構建數據對象。它需要一個空的構造函數。你在你的數據對象中使用Uri。所以只需將Uri的地址保存爲字符串。這將解決問題。

來源

2017-01-01 06:03:31

如果你看到教程你會看到，這是它用來保存共享首選項中的數組列表 –

是的，但他們沒有使用gson bro存儲「Uri」。你的數據對象中不應該有Uri類。 –

我認爲問題在這裏;

String json = preferences.getString("audioArrayList", null);

如果prefs中沒有audioArrayList，則默認返回null。然後你的

gson.fromJson(json, type);

出現故障。順便說一句，我通常設置類的任何我期待從該類型的JSON字符串。任何具體的使用原因

Type type = new TypeToken<ArrayList<Songfileinfo>>()

來源

2016-12-31 18:00:50

新年快樂，你是對的看到更新的問題，我包括了重要的幾點 –

雅我試圖保存數組列表共享首選項使用gson –

使用gson保存數據和媒體播放器服務時出現錯誤

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