Android 数据库查询报错

Question

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor android.database.sqlite.SQLiteDatabase.rawQuery(java.lang.String, java.lang.String[])' on a null object reference        报错行代码：Cursor cursor = mSQLiteDatabase.rawQuery("select * from users",null);

Answer 1

mSQLiteDatabase需要声明定义一下

Answer 2

Cursor cursor = mSQLiteDatabase.rawQuery("select * from users",new String[0]);