錯誤： - 服務類沒有零參數構造函數

我是新來的android。我想在我的活動中使用服務來獲取時間間隔後的JSON數據。我的服務類是我的記錄類的內部類。我在我的服務類中創建了一個空的構造函數，並嘗試了不同的方法，但每次出現錯誤時都會嘗試。任何人都可以請指導我解決這個問題嗎？錯誤： - 服務類沒有零參數構造函數

record.class

public class record extends Activity{ 
..... 
private static String url ="https://podgier-woman.000webhostapp.com/table.php"; 
JSONParser jParser = new JSONParser(); 
...... 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.record); 
    ...... 

    Intent intent = new Intent(record.this, 
      BackgroundService.class); 

    startService(intent); 

} 


    class gro extends AsyncTask<String, String, String> { 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     ............ 
     } 
    } 

    protected String doInBackground(String... args) { 
     java.util.List<NameValuePair> pr = new ArrayList<NameValuePair>(); 

     JSONObject json = jParser.makeHttpRequest(url, "GET", pr); 

     try { 
      JSONArray code = json.getJSONArray("code"); 
      Log.d("list :",code.toString()); 
      for (int i = 0; i < code.length(); i++) { 
       JSONObject c = code.getJSONObject(i); 

       asd.add(c.getString("name")); 

       // adding each child node to HashMap key => value 

       // adding contact to contact list 
       JSONArray p = null; 
      } 
      }catch(JSONException e){ 

      } 
      return null; 

    } 

    protected void onPostExecute(String file_url) { 

     pDialog.dismiss(); 
     .......... 

     Collections.reverse(Arrays.asList(info)); 
     customList = new CustomList(record.this,info); 
     listView = (ListView) findViewById(R.id.listView); 
     listView.setAdapter(customList); 


    } 
} 

//----------------------------------------------------------------------------------------------------------------------- 
// 
// 
//----------------------------------------------------------------------------------------------------------------------- 
public class BackgroundService extends Service 
{ 
    public BackgroundService(){ 
     super(); 
    } 

    private static final String TAG = "BackgroundService"; 
    private ThreadGroup myThreads = new ThreadGroup("ServiceWorker"); 



    @Override 
    public void onCreate() { 
     super.onCreate(); 
     Log.v(TAG, "in onCreate()"); 

    } 


    @Override 
    public int onStartCommand(Intent intent, int flags, int startId) 
    { 
     super.onStartCommand(intent, flags, startId); 
     int counter = intent.getExtras().getInt("counter"); 



     Log.v(TAG, "in onStartCommand(), counter = " + counter + 
       ", startId = " + startId); 

     new Thread(myThreads, new ServiceWorker(counter), "BackgroundService") 
       .start(); 


     return START_NOT_STICKY; 
    } 


    class ServiceWorker implements Runnable 
    { 
     private int counter = -1; 

     public ServiceWorker(int counter) { 
      this.counter = counter; 
     } 

     public void run() { 

      final String TAG2 = "ServiceWorker:" + Thread.currentThread().getId(); 
      // do background processing here... 
      try { 
       Log.e(TAG2, "sleeping for 5 seconds. counter = " + counter); 

       while(true) 
       { 
        Thread.sleep(5000); 
        Log.e("agdghdgdgdrgrdgrdg","dgdgd"); 
        new gro().execute(); 
       } 
      } catch (InterruptedException e) { 
       Log.e(TAG2, "... sleep interrupted"); 
      } 
     } 
    } 

    @Override 
    public void onDestroy() 
    { 

    } 
    @Override 
    public IBinder onBind(Intent intent) { 
     Log.v(TAG, "in onBind()"); 
     return null; 
    } 


} 



}

的manifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.grover.jsonp"> 
<uses-permission android:name="android.permission.INTERNET"/> 
<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:supportsRtl="true" 
    android:theme="@style/AppTheme"> 
    <activity 
     android:name=".record" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme.NoActionBar"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <service android:name=".record$BackgroundService"/> 
</application>

logcat的

E/AndroidRuntime: FATAL EXCEPTION: main 
       Process: com.grover.jsonp, PID: 13046 
       java.lang.RuntimeException: Unable to instantiate service com.grover.jsonp.record$BackgroundService: java.lang.InstantiationException: class com.grover.jsonp.record$BackgroundService has no zero argument constructor 
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:2721) 
        at android.app.ActivityThread.access$1800(ActivityThread.java:147) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1368) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:135) 
        at android.app.ActivityThread.main(ActivityThread.java:5237) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:372) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:707) 
       Caused by: java.lang.InstantiationException: class com.grover.jsonp.record$BackgroundService has no zero argument constructor 
        at java.lang.Class.newInstance(Class.java:1563) 
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:2718) 
        at android.app.ActivityThread.access$1800(ActivityThread.java:147)  
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1368)  
        at android.os.Handler.dispatchMessage(Handler.java:102)  
        at android.os.Looper.loop(Looper.java:135)  
        at android.app.ActivityThread.main(ActivityThread.java:5237)  
        at java.lang.reflect.Method.invoke(Native Method)  
        at java.lang.reflect.Method.invoke(Method.java:372)  
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)  
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:707)  
       Caused by: java.lang.NoSuchMethodException: <init> [] 
        at java.lang.Class.getConstructor(Class.java:531) 
        at java.lang.Class.getDeclaredConstructor(Class.java:510) 
        at java.lang.Class.newInstance(Class.java:1561) 
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:2718)  
        at android.app.ActivityThread.access$1800(ActivityThread.java:147)  
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1368)  
        at android.os.Handler.dispatchMessage(Handler.java:102)  
        at android.os.Looper.loop(Looper.java:135)  
        at android.app.ActivityThread.main(ActivityThread.java:5237)  
        at java.lang.reflect.Method.invoke(Native Method)  
        at java.lang.reflect.Method.invoke(Method.java:372)  
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)  
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:707)

來源

2017-08-01 cobragin neshi

以下。 – Dennis

首先，您嘗試使用一個推出Bounded ServiceIntent。這是錯誤的。爲了做到這一點，你需要創建一個Intent Service

你得到的，因爲你一個無參數的構造例外您的服務沒有綁定到你的MainActivity」是不正確，與構造的問題無關，與是否使用startService（）或bindService（）（Thanks）

要創建一個BoundService，你需要一個iBinder對象來綁定你的服務，我知道這很奇怪，但這就是Android得知它的方式。已經閱讀，有兩種服務

1. Intent Service 
2. Bound Service

Bound Service需要像這樣實例化。

用此編輯您的代碼，請確保您更新我的onBind()。

public class BackgroundService extends Service 
{ 
    public BackgroundService(){ 
     super(); 
    } 
    private BackgroundService mBS; 

    // This is the object that receives interactions from clients. See 
    // RemoteService for a more complete example. 
    private final IBinder mBinder = new LocalBinder(); 

    /** 
    * Class for clients to access. Because we know this service always 
    * runs in the same process as its clients, we don't need to deal with 
    * IPC. 
    */ 
    public class LocalBinder extends Binder { 
     BackgroundService getService() { 
      return BackgroundService.this; 
     } 
    } 


    @Override 
    public IBinder onBind(Intent intent) { 
     Log.v(TAG, "in onBind()"); 
     return mBinder; 
    } 

}

在MainActivity

你需要一個接口 - >ServiceConnection

添加在問這個問題之前，應該先完成一些R＆d在MainActivity.java

BackgroundService mBackgroundService; 
boolean mServiceBound = false; 

private ServiceConnection mServiceConnection = new ServiceConnection() { 


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

@Override 
public void onServiceConnected(ComponentName name, IBinder service) { 
    LocalBinder myBinder = (LocalBinder) service; 
    mBackgroundService = myBinder.getService(); 
    mServiceBound = true; 
} 
}; 
    //Start the service when the activity starts 
    @Override 
protected void onStart() { 
    super.onStart(); 
    Intent intent = new Intent(this, BackgroundService.class); 
    startService(intent); 
    bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE); 
} 

@Override 
protected void onStop() { 
    super.onStop(); 
    if (mServiceBound) { 
     unbindService(mServiceConnection); 
     mServiceBound = false; 
    } 
}

來源

2017-08-01 13:04:31 Dennis

請詳細解釋**如何清除問題中所述的例外情況。 – CommonsWare

@CommonsWare請看看。謝謝！ – Dennis

嗯，解釋說，你不必投票它@CommonsWare。 – 2017-08-01 13:22:35

錯誤： - 服務類沒有零參數構造函數

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