我正在尝试以下代码,其中一个服务正在实现我的监听器：
public class MyListenerClass extends Service implements MyListenerInterface {
public void onCurrencyRecieved(MyEventClass event) {
System.out.println("Coins Recieved - Listener Successful");
stopSelf();
Toast toast = Toast.makeText(getApplicationContext(),"Service Stopped",Toast.LENGTH_LONG);
toast.show();
}
@Override
public void onCreate() {
Toast toast = Toast.makeText(getApplicationContext(),"Service started",Toast.LENGTH_LONG);
toast.show();
super.onCreate();
}
现在,onCreate()内部的toast工作正常,但是在重写方法内部抛出以下异常：
01-03 18:52:35.740: ERROR/AndroidRuntime(2388): java.lang.NullPointerException 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:100) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at com.test.listenertest1.MyListenerClass.onCurrencyRecieved(MyListenerClass.java:28) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at com.test.listenertest1.MyEventGenerator.generateEvent(MyEventGenerator.java:34) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at com.test.listenertest1.MyEventGenerator.<init>(MyEventGenerator.java:16) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at com.test.listenertest1.NewActivity.onKeyDown(NewActivity.java:33) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.view.KeyEvent.dispatch(KeyEvent.java:1037) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.app.Activity.dispatchKeyEvent(Activity.java:2046) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1631) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2368) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2338) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.view.ViewRoot.handleMessage(ViewRoot.java:1641) 01-03 18:52:35.740: ERROR/AndroidRuntime(2388): at android.os.Handler.dispatchMessage(Handler.java:99)
我想我错过了一些重要的java概念.我们不能在重写方法中使用getApplicationContext()吗？
