NullPointerException异常在sendBroadcast（）从服务到活动 [英] NullPointerException at sendBroadcast() from Service to Activity
问题描述
我有一个服务类，哪些是应该从服务类接收广播与主活性的研究类方法sendBroadcast。
其上运行的方法时崩溃 sendBroadcast 从我服务类。
这是我的服务类的一部分（ EDITED ）
公共静态最终诠释STATE_CONNECTING = 1; 公共静态最后弦乐BT_CONNECTING =com.android.mypackage.action.BTService.BT_CONNECTING; 私人最终的IBinder mBinder =新LocalBinder（）; 公共类LocalBinder扩展宾德（）{
BTService的getService（）{
返回BTService.this;
}
} @覆盖
公众的IBinder onBind（意向意图）{
返回mBinder;
} 公共同步无效的setState（INT状态）{
mState =状态;
如果（状态== STATE_CONNECTING）{
意图myIntent =新意图（BT_CONNECTING）;
尝试{
sendBroadcast（myIntent）;
}
赶上（NullPointerException异常五）{}
}
}
这是应该接收广播意图我Activity类的一部分（ EDITED ）
私人广播接收器接收器=新的广播接收器（）{
@覆盖
公共无效的onReceive（上下文的背景下，意图意图）{
如果（intent.getAction（）。等于（BTService.BT_CONNECTING））
mState = STATE_CONNECTING;
}
}; 私人ServiceConnection mConnection =新ServiceConnection（）{
公共无效onServiceConnected（组件名的className，服务的IBinder）{
LocalBinder粘结剂=（LocalBinder）服务;
为myService = binder.getService（）;
mBound = TRUE;
} 公共无效onServiceDisconnected（组件名称为arg0）{
mBound = FALSE;
}
}; @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
意向意图=新意图（这一点，BTService.class）;
myService.bindService（意向，mConnection，Context.BIND_AUTO_CREATE）; IntentFilter的过滤器=新的IntentFilter（BTService.BTConnecting）;
registerReceiver（接收器，过滤器）;
}
调用sendBroadcast（意向）方法时，我得到NullPointerException异常。解决这个任何提示大大AP preciated。
下面是日志：
致命异常：主要
了java.lang.RuntimeException：无法启动活动ComponentInfo {com.android.mypackage / com.android.mypackage.MyActivity}：显示java.lang.NullPointerException
在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2787）
在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2803）
在android.app.ActivityThread.access $ 2300（ActivityThread.java:135）
在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:2136）
在android.os.Handler.dispatchMessage（Handler.java:99）
在android.os.Looper.loop（Looper.java:144）
在android.app.ActivityThread.main（ActivityThread.java:4937）
在java.lang.reflect.Method.invokeNative（本机方法）
在java.lang.reflect.Method.invoke（Method.java:521）
在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:868）
在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:626）
在dalvik.system.NativeStart.main（本机方法）
显示java.lang.NullPointerException：产生的原因
在android.content.ContextWrapper.sendBroadcast（ContextWrapper.java:271）
在com.android.mypackage.BTService.setState（BTService.java:68）
在com.android.mypackage.BTService.connect（BTService.java:90）
在com.android.mypackage.MyActivity.onCreate（MyActivity.java:78）
在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1069）
在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2751）
从你的堆栈跟踪，看来你有某种直接引用您的 BTService 服务。既然你砍你的的onCreate（）总之我不能肯定你是怎么做的，但我会采取一种猜测。
你有没有你的活动内直接实例化服务（使用新BTService（））？如果是这样，那么你收到此错误的原因是因为你的服务没有绑定到它的上下文。你必须让Android的为您创建的服务，通过调用 startService（）或 bindService（）。
I have a Service class and an main Acitivity class which is supposed to receive broadcasts from the Service class with method sendBroadcast.
It crashes when running the method sendBroadcast from my Service class.
here is part of my Service class (EDITED):
public static final int STATE_CONNECTING = 1;
public static final String BT_CONNECTING = "com.android.mypackage.action.BTService.BT_CONNECTING";
private final IBinder mBinder = new LocalBinder();
public class LocalBinder extends Binder() {
BTService getService() {
return BTService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
public synchronized void setState(int state) {
mState = state;
if ( state == STATE_CONNECTING ) {
Intent myIntent = new Intent(BT_CONNECTING);
try {
sendBroadcast(myIntent);
}
catch (NullPointerException e) {}
}
}
And here is part of my Activity class which is supposed to receive the broadcasted intents (EDITED):
private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(BTService.BT_CONNECTING))
mState = STATE_CONNECTING;
}
};
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
LocalBinder binder = (LocalBinder) service;
myService = binder.getService();
mBound = true;
}
public void onServiceDisconnected(ComponentName arg0) {
mBound = false;
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
Intent intent = new Intent(this, BTService.class);
myService.bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
IntentFilter filter = new IntentFilter(BTService.BTConnecting);
registerReceiver(receiver, filter);
}
I get NullPointerException when calling sendBroadcast(intent) method. Any tips on solving this is greatly appreciated.
here is the log:
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.mypackage/com.android.mypackage.MyActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2787)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2803)
at android.app.ActivityThread.access$2300(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2136)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:144)
at android.app.ActivityThread.main(ActivityThread.java:4937)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.sendBroadcast(ContextWrapper.java:271)
at com.android.mypackage.BTService.setState(BTService.java:68)
at com.android.mypackage.BTService.connect(BTService.java:90)
at com.android.mypackage.MyActivity.onCreate(MyActivity.java:78)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1069)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2751)
From your stack trace, it appears you are somehow directly referencing your BTService service. Since you cut your onCreate() short I can't be certain how you are doing it, but I will take a guess.
Did you instantiate this service directly inside of your activity (use new BTService())? If so, then the reason you are getting this error is because your Service has no context bound to it. You must let Android create your service for you by calling startService() or bindService().
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