我正在尝试在创建活动时设置闹钟但我得到空指针异常。但是，当我通过按钮点击设置闹钟时效果很好。
所以我尝试了很多东西，包括在活动的onCreate（）方法内的不同线程上设置方法但仍然获得NPE。
我还尝试将我的活动的onCreate方法设置为public，但结果仍然相同。有什么建议吗？
logcat的：
11-08 13:51:17.109: E/AndroidRuntime(26046): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.snapttechtechnologies.stevekamau.wehappening/com.snapttechtechnologies.stevekamau.wehappening.activities.AddEvent}: java.lang.NullPointerException
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2429)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread.access$800(ActivityThread.java:151)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.os.Handler.dispatchMessage(Handler.java:110)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.os.Looper.loop(Looper.java:193)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread.main(ActivityThread.java:5333)
11-08 13:51:17.109: E/AndroidRuntime(26046): at java.lang.reflect.Method.invokeNative(Native Method)
11-08 13:51:17.109: E/AndroidRuntime(26046): at java.lang.reflect.Method.invoke(Method.java:515)
11-08 13:51:17.109: E/AndroidRuntime(26046): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
11-08 13:51:17.109: E/AndroidRuntime(26046): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
11-08 13:51:17.109: E/AndroidRuntime(26046): at dalvik.system.NativeStart.main(Native Method)
11-08 13:51:17.109: E/AndroidRuntime(26046): Caused by: java.lang.NullPointerException
11-08 13:51:17.109: E/AndroidRuntime(26046): at com.snapttechtechnologies.stevekamau.wehappening.helper.ScheduleClient.setAlarmForNotification(ScheduleClient.java:60)
11-08 13:51:17.109: E/AndroidRuntime(26046): at com.snapttechtechnologies.stevekamau.wehappening.activities.AddEvent.setAlarmTime(AddEvent.java:54)
11-08 13:51:17.109: E/AndroidRuntime(26046): at com.snapttechtechnologies.stevekamau.wehappening.activities.AddEvent.onCreate(AddEvent.java:38)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.Activity.performCreate(Activity.java:5343)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
11-08 13:51:17.109: E/AndroidRuntime(26046): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2331)
AddEvent.java
public class AddEvent extends AppCompatActivity {
private ScheduleClient scheduleClient;
// This is the date picker used to select the date for our notification
private DatePicker picker;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.events_wehappened);
// Create a new service client and bind our activity to this service
scheduleClient = new ScheduleClient(this);
scheduleClient.doBindService();
setAlarmTime();
}
public void setAlarmTime() {
String input = "Sun Nov 08 2015 13:38";
Calendar cal = Calendar.getInstance();
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd yyyy HH:mm", Locale.ENGLISH);
try {
date = sdf.parse(input);
} catch (ParseException e) {
e.printStackTrace();
}
cal.setTime(date);
cal.add(Calendar.MINUTE, -60);
// Ask our service to set an alarm for that date, this activity talks to the client that talks to the service
scheduleClient.setAlarmForNotification(cal);
// Notify the user what they just did
Toast.makeText(this, "Notification set for: " + cal, Toast.LENGTH_SHORT).show();
}
/**
* This is the onClick called from the XML to set a new notification
*/
public void onDateSelectedButtonClick(View v) {
String input = "Sun Nov 08 2015 13:38";
Calendar cal = Calendar.getInstance();
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd yyyy HH:mm", Locale.ENGLISH);
try {
date = sdf.parse(input);
} catch (ParseException e) {
e.printStackTrace();
}
cal.setTime(date);
cal.add(Calendar.MINUTE, -60);
// Ask our service to set an alarm for that date, this activity talks to the client that talks to the service
scheduleClient.setAlarmForNotification(cal);
// Notify the user what they just did
Toast.makeText(this, "Notification set for: " + cal, Toast.LENGTH_SHORT).show();
}
@Override
protected void onStop() {
// When our activity is stopped ensure we also stop the connection to the service
// this stops us leaking our activity into the system *bad*
if (scheduleClient != null)
scheduleClient.doUnbindService();
super.onStop();
}
ScheduleClient.java
/**
* This is our service client, it is the 'middle-man' between the
* service and any activity that wants to connect to the service
*
* @author paul.blundell
*/
public class ScheduleClient {
// The hook into our service
private ScheduleService mBoundService;
// The context to start the service in
private Context mContext;
// A flag if we are connected to the service or not
private boolean mIsBound;
/**
* When you attempt to connect to the service, this connection will be called with the result.
* If we have successfully connected we instantiate our service object so that we can call methods on it.
*/
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
// This is called when the connection with our service has been established,
// giving us the service object we can use to interact with our service.
mBoundService = ((ScheduleService.ServiceBinder) service).getService();
}
public void onServiceDisconnected(ComponentName className) {
mBoundService = null;
}
};
public ScheduleClient(Context context) {
mContext = context;
}
/**
* Call this to connect your activity to your service
*/
public void doBindService() {
// Establish a connection with our service
mContext.bindService(new Intent(mContext, ScheduleService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
/**
* Tell our service to set an alarm for the given date
*
* @param c a date to set the notification for
*/
public void setAlarmForNotification(Calendar c) {
mBoundService.setAlarm(c);
}
/**
* When you have finished with the service call this method to stop it
* releasing your connection and resources
*/
public void doUnbindService() {
if (mIsBound) {
// Detach our existing connection.
mContext.unbindService(mConnection);
mIsBound = false;
}
}
}
答案 0 :(得分：1)
绑定服务不是同步的。您在请求绑定服务连接后立即调用服务方法，并且绑定尚未完成。
您可以使用onServiceConnected()上的ServiceConnection回调来了解服务的绑定时间。