每当我试图加载了我的活动我得到一个空指针异常,应用程序崩溃日志猫指出,这个代码我不断收到一个空指针异常,每当我发起一个活动
public Cursor getScores() {
return ourDatabase.rawQuery("SELECT * FROM "+DATABASE_TABLE, new String[0]);
}
及以下logcat的
02-18 10:12:37.719: E/AndroidRuntime(404): FATAL EXCEPTION: main
02-18 10:12:37.719: E/AndroidRuntime(404): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.connectfour/com.example.connectfour.ScoreActivity}: java.lang.NullPointerException
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.os.Handler.dispatchMessage(Handler.java:99)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.os.Looper.loop(Looper.java:123)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread.main(ActivityThread.java:3683)
02-18 10:12:37.719: E/AndroidRuntime(404): at java.lang.reflect.Method.invokeNative(Native Method)
02-18 10:12:37.719: E/AndroidRuntime(404): at java.lang.reflect.Method.invoke(Method.java:507)
02-18 10:12:37.719: E/AndroidRuntime(404): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-18 10:12:37.719: E/AndroidRuntime(404): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-18 10:12:37.719: E/AndroidRuntime(404): at dalvik.system.NativeStart.main(Native Method)
02-18 10:12:37.719: E/AndroidRuntime(404): Caused by: java.lang.NullPointerException
02-18 10:12:37.719: E/AndroidRuntime(404): at com.example.connectfour.Database.getScores(Database.java:57)
02-18 10:12:37.719: E/AndroidRuntime(404): at com.example.connectfour.ScoreActivity$MyCursorAdapter.<init> (ScoreActivity.java:21)
02-18 10:12:37.719: E/AndroidRuntime(404): at com.example.connectfour.ScoreActivity.onCreate(ScoreActivity.java:49)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-18 10:12:37.719: E/AndroidRuntime(404): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
02-18 10:12:37.719: E/AndroidRuntime(404):
你'NPE'上'Database.java:57',检查第57行。 –
Database.java中的第57行是什么? – InnocentKiller
确保DATABASE_TABLE不为空并尝试:'返回ourDatabase.rawQuery(“SELECT * FROM”+ DATABASE_TABLE,null);' – Ayoub