我开发了一个应用程序，允许用户保存他最喜欢的两个停车位。它使用服务从sqlite数据库中检索相关的停车信息。在数据库中我有这个方法来查找第一个条目：
public Cursor firstentry(){
String select = "SELECT PREF1, PREF2 FROM parking_table WHERE id =1";
Cursor cursor = db.rawQuery(select, null);
return cursor;
每当我运行我的应用程序时，当服务尝试使用以下命令调用此方法时，会出现强制关闭错误：
Cursor c = dh.firstentry();
它给出了错误，就像我评论时一样，应用程序运行正常。
这是错误的logcat：
04-08 18:56:38.673: E/AndroidRuntime(13166): FATAL EXCEPTION: Timer-0
04-08 18:56:38.673: E/AndroidRuntime(13166): java.lang.NullPointerException
04-08 18:56:38.673: E/AndroidRuntime(13166): at stefan.testservice.ConnectionService$1.run(ConnectionService.java:64)
04-08 18:56:38.673: E/AndroidRuntime(13166): at java.util.Timer$TimerImpl.run(Timer.java:284)
04-08 18:56:39.654: E/ActivityThread(13166): Activity stefan.testservice.TestserviceActivity has leaked IntentReceiver stefan.testservice.TestserviceActivity$2@40521b78 that was originally registered here. Are you missing a call to unregisterReceiver()?
04-08 18:56:39.654: E/ActivityThread(13166): android.app.IntentReceiverLeaked: Activity stefan.testservice.TestserviceActivity has leaked IntentReceiver stefan.testservice.TestserviceActivity$2@40521b78 that was originally registered here. Are you missing a call to unregisterReceiver()?
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.LoadedApk$ReceiverDispatcher.<init>(LoadedApk.java:756)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.LoadedApk.getReceiverDispatcher(LoadedApk.java:551)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.ContextImpl.registerReceiverInternal(ContextImpl.java:795)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.ContextImpl.registerReceiver(ContextImpl.java:782)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.ContextImpl.registerReceiver(ContextImpl.java:776)
04-08 18:56:39.654: E/ActivityThread(13166): at android.content.ContextWrapper.registerReceiver(ContextWrapper.java:318)
04-08 18:56:39.654: E/ActivityThread(13166): at stefan.testservice.TestserviceActivity$1.onServiceConnected(TestserviceActivity.java:280)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.LoadedApk$ServiceDispatcher.doConnected(LoadedApk.java:1064)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.LoadedApk$ServiceDispatcher$RunConnection.run(LoadedApk.java:1081)
04-08 18:56:39.654: E/ActivityThread(13166): at android.os.Handler.handleCallback(Handler.java:587)
04-08 18:56:39.654: E/ActivityThread(13166): at android.os.Handler.dispatchMessage(Handler.java:92)
04-08 18:56:39.654: E/ActivityThread(13166): at android.os.Looper.loop(Looper.java:123)
04-08 18:56:39.654: E/ActivityThread(13166): at android.app.ActivityThread.main(ActivityThread.java:3683)
04-08 18:56:39.654: E/ActivityThread(13166): at java.lang.reflect.Method.invokeNative(Native Method)
04-08 18:56:39.654: E/ActivityThread(13166): at java.lang.reflect.Method.invoke(Method.java:507)
04-08 18:56:39.654: E/ActivityThread(13166): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-08 18:56:39.654: E/ActivityThread(13166): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-08 18:56:39.654: E/ActivityThread(13166): at dalvik.system.NativeStart.main(Native Method)
04-08 18:56:40.054: E/ActivityThread(13166): Activity stefan.testservice.TestserviceActivity has leaked ServiceConnection stefan.testservice.TestserviceActivity$1@40521790 that was originally bound here
04-08 18:56:40.054: E/ActivityThread(13166): android.app.ServiceConnectionLeaked: Activity stefan.testservice.TestserviceActivity has leaked ServiceConnection stefan.testservice.TestserviceActivity$1@40521790 that was originally bound here
04-08 18:56:40.054: E/ActivityThread(13166): at android.app.LoadedApk$ServiceDispatcher.<init>(LoadedApk.java:938)
04-08 18:56:40.054: E/ActivityThread(13166): at android.app.LoadedApk.getServiceDispatcher(LoadedApk.java:833)
04-08 18:56:40.054: E/ActivityThread(13166): at android.app.ContextImpl.bindService(ContextImpl.java:867)
04-08 18:56:40.054: E/ActivityThread(13166): at android.content.ContextWrapper.bindService(ContextWrapper.java:347)
04-08 18:56:40.054: E/ActivityThread(13166): at stefan.testservice.TestserviceActivity.doBindService(TestserviceActivity.java:290)
04-08 18:56:40.054: E/ActivityThread(13166): at stefan.testservice.TestserviceActivity$DownloadTask.onPostExecute(TestserviceActivity.java:193)
04-08 18:56:40.054: E/ActivityThread(13166): at android.os.AsyncTask.finish(AsyncTask.java:417)
04-08 18:56:40.054: E/ActivityThread(13166): at android.os.AsyncTask.access$300(AsyncTask.java:127)
04-08 18:56:40.054: E/ActivityThread(13166): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
04-08 18:56:40.054: E/ActivityThread(13166): at android.os.Handler.dispatchMessage(Handler.java:99)
04-08 18:56:40.054: E/ActivityThread(13166): at android.os.Looper.loop(Looper.java:123)
04-08 18:56:40.054: E/ActivityThread(13166): at android.app.ActivityThread.main(ActivityThread.java:3683)
04-08 18:56:40.054: E/ActivityThread(13166): at java.lang.reflect.Method.invokeNative(Native Method)
04-08 18:56:40.054: E/ActivityThread(13166): at java.lang.reflect.Method.invoke(Method.java:507)
04-08 18:56:40.054: E/ActivityThread(13166): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-08 18:56:40.054: E/ActivityThread(13166): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-08 18:56:40.054: E/ActivityThread(13166): at dalvik.system.NativeStart.main(Native Method)
任何帮助都非常受欢迎，因为我尝试了一切，似乎没有任何工作。提前谢谢！
编辑：
停车表代码：
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE_NAME + "(id INTEGER PRIMARY KEY, PREF1 TEXT, PREF2 TEXT)");
}
答案 0 :(得分：0)
它的nullpointerexception意味着当时数据库中可能没有任何内容。如果游标为空则需要处理
单步执行代码实际上是确切查看null的唯一方法。虽然很难说出你发布的内容，但肯定需要更多的代码
答案 1 :(得分：0)
您正在运行rawsql，因此请检查确切的查询是否对您的数据库有效，SELECT PREF1, PREF2 FROM parking_table WHERE id =1
是PREF1的确切（有大小写）列的名称??
答案 2 :(得分：0)
如果您没有SQLite浏览器软件，请在此处获取： SQLite Browser
当我使用SQLite时，它会有所帮助。我之前遇到过这个问题，我通过在查询中添加id参数来解决它。基本上，您需要将查询更改为：
public Cursor firstentry(){
String select = "SELECT id, PREF1, PREF2 FROM parking_table WHERE id =1";
Cursor cursor = db.rawQuery(select, null);
return cursor;
如果c.moveToFirst()是光标的名称，请不要忘记调用c。
答案 3 :(得分：0)
我设法解决了，一切都很好，我只需要初始化类对象。这是所需的代码行：
this.yourobject = new class(this);
就我而言：
this.dh = new SQLHelper(this);
希望有所帮助：）