Android错误从LocationListener类将位置数据写入SQLite数据库

我有一个应用程序,其中我有一个实现LOCATIOnlistener的服务类.我希望能够将onLOCATIOnChanged()中收到的位置传递回我的主要活动.到目前为止,我一直在尝试通过写入sqlite数据库来实现这一点,但在尝试打开数据库时可能会出现错误.我认为它与没有写上下文有关,但我无法弄明白.但是,当我在onCreate()中执行此操作时,写入数据库的工作完全正常.我最初只是尝试这样做：

@Override
    public void onLOCATIOnChanged(LOCATIOn loC) {//Spits out single LOCATIOn for current disconnect
        System.out.println("LOCATIOn equals "+loc);
        latitude=Double.toString(loc.getLatitude());
        longitude=Double.toString(loc.getLongitude());
        writeToDb(MyLocListener.this,latitude,longitudE);       
        man.removeupdates(listener);//Stops LOCATIOn manager from listening for updates
        listener=null;
        man=null;
    }

public void writeToDb(Co@R_618_10443@t co@R_618_10443@t,String latitude,String longitudE){
    db=new DbAdapter(co@R_618_10443@t);
    db.openToWrite();
    db.deleteAll();
    db.insert(latitudE);
    db.insert(longitudE);
    db.close();
}

但这没用,每次都会在db.openToWrite()行上给我一个nullPointerException. getApplicationCo@R_618_10443@t()在这里也不起作用.

我现在修改它以在一个线程中写入DB：

@Override
public void onLOCATIOnChanged(LOCATIOn loC) {//Spits out single LOCATIOn for current disconnect
    System.out.println("LOCATIOn equals "+loc);
    latitude=Double.toString(loc.getLatitude());
    longitude=Double.toString(loc.getLongitude());
    Runnable runner=new SaveLOCATIOn(latitude,longitudE);
    new Thread(runner).start();
    man.removeupdates(listener);//Stops LOCATIOn manager from listening for updates
    listener=null;
    man=null;
}

public class SaveLOCATIOn implements Runnable{
        String latitude;
        String longitude;
    //  DbAdapter db;
        public SaveLOCATIOn(String latitude,String longitudE){
            this.latitude=latitude;
            this.longitude=longitude;

        }
        @Override
        public void run() {
            db.openToWrite();
            db.deleteAll();
            db.insert(latitudE);
            db.insert(longitudE);
            db.close();     
        }
    }

我在onCreate()方法中初始化数据库为：

public class MyLocListener extends service implements LOCATIOnListener{ 
    static LOCATIOnManager man;
    static LOCATIOnListener listener;
    static LOCATIOn LOCATIOn;
    public DbAdapter db;

    @Override
    public void onCreate() {
        super.onCreate();   
        this.db=new DbAdapter(MyLocListener.this);
    }

但是现在,第二次尝试一直给我一个更加精简的错误,但它仍然在我试图打开数据库可写的行上出错.行MyLocListener.java:92引用行db.openToWrite();

错误是：

05-30 15:35:19.698: W/dalvikvm(4557): threadid=9: thread exiTing with uncaught exception (group=0x4001d7e0)
05-30 15:35:19.706: E/AndroidRuntime(4557): FATAL EXCEPTION: Thread-10
05-30 15:35:19.706: E/AndroidRuntime(4557): java.lang.NullPointerException
05-30 15:35:19.706: E/AndroidRuntime(4557):     at com.phonehalo.proto.MyLocListener$SaveLOCATIOn.run(MyLocListener.java:92)
05-30 15:35:19.706: E/AndroidRuntime(4557):     at java.lang.Thread.run(Thread.java:1096)