Question

我在getReadbleDatabase

获取了一个nullpointer异常

 public List<Offer> getOffers(String offer_category)
        {
            db = this.getReadableDatabase();
            String sql = "select * from offer_db "+TABLE_OFFER + " where "+ OFFER_CATEGORY+ " is "+ offer_category;
            Cursor cur = db.rawQuery(sql,null);
            cur.moveToFirst();
       }

这里是logcat数据

引起：java.lang.NullPointerException at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked（SQLiteOpenHelper.java:224）在 android.database.sqlite.SQLiteOpenHelper.getReadableDatabase（SQLiteOpenHelper.java:188）在 com.example.shreyfrapp.DatabaseHandler.getOffers（DatabaseHandler.java:61）在com.example.shreyfrapp.FragmentTab1.onCreate（FragmentTab1.java:39）在android.app.Fragment.performCreate（Fragment.java:1678）at android.app.FragmentManagerImpl.moveToState（FragmentManager.java:859）在 android.app.FragmentManagerImpl.moveToState（FragmentManager.java:1062）在android.app.BackStackRecord.run（BackStackRecord.java:684）at android.app.FragmentManagerImpl.execPendingActions（FragmentManager.java:1447）在android.app.Activity.performStart（Activity.java:5240）at android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2168）在 android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2245）在android.app.ActivityThread.access $ 800（ActivityThread.java:135）at android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1196）在android.os.Handler.dispatchMessage（Handler.java:102）at android.os.Looper.loop（Looper.java:136）at android.app.ActivityThread.main（ActivityThread.java:5021）at java.lang.reflect.Method.invokeNative（Native Method）at java.lang.reflect.Method.invoke（Method.java:515）at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:827）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:643）at dalvik.system.NativeStart.main（原生方法）

Answer 1

以大写字母提供查询，并在“是”的位置尝试“=”。为什么你在选择查询中将光标移动到第一位？

getReadableDatabase第一行的NullPointerException

1 个答案: