本文选自系列文章之一，本系列文章将为读者分享国外最优质的精彩问与答，供读者学习和了解国外最新技术。在Android中启动Service时出现“undefined intent constructor”的错误，怎么办？
我在Activity中尝试启动Service，但出现“undefined intent constructor”的报错信息。
MyService.java代码如下：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | public class MyService extends Service { @Override public IBinder onBind(Intent intent) { return null ; } public static boolean isInstanceCreated() { return instance != null ; } @Override public void onCreate() { Toast.makeText( this , "My Service Created" , Toast.LENGTH_LONG).show(); Log.d(TAG, "onCreate" ); instance = this ; } @Override public void onDestroy() { Toast.makeText( this , "My Service Stopped" , Toast.LENGTH_LONG).show(); Log.d(TAG, "onDestroy" ); instance = null ; } @Override public void onStart(Intent intent, int startid) { Toast.makeText(getBaseContext(), "Service started" ,Toast.LENGTH_SHORT).show(); } } |
启动SampleService.java的代码如下：
| 1 2 3 4 5 6 7 8 9 | public class SampleService extends Activity{ @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.grid_activity); Intent myintent = new Intent(SampleService. this ,MyService. this ); //Error show here.. startService(myintent); } } |
在manifest file中设定service的初值如下：
| 1 | <service android:enabled= "true" android:name= "com.MyApp.MyService" /> |
请大家帮我解决这个错误。
(最佳答案）
你不应该使用Service.this，而应该按如下方法改变class：
| 1 | Intent myintent = new Intent(SampleService. this ,MyService.Class); |
做如下调整：
| 1 | Intent myintent = new Intent(SampleService. this ,MyService. this ); |
变为：
| 1 2 | Intent myintent = new Intent(SampleService. this ,MyService.Class); // first param is a context second param is a class in your case a MyServiceClass |
你没有设置类似于Intent(SampleService, MyService)的构造函数，在intent constructor参数设定上出现错误。
| 1 2 3 4 5 6 7 8 9 10 | public Intent (Context packageContext, Class<?> cls) Added in API level 1 Create an intent for a specific component. All other fields (action, data, type, class) are null , though they can be modified later with explicit calls. This provides a convenient way to create an intent that is intended to execute a hard-coded class name, rather than relying on the system to find an appropriate class for you; see setComponent(ComponentName) for more information on the repercussions of this . Parameters packageContext A Context of the application package implementing this class. cls The component class that is to be used for the intent. |
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