How to get a single SQLite row data with its id?

Question

I have successfully retrieved SQLite data to ListView. Now I am trying to implement OnItemClickListener to show the data in Dialog but I am getting this error

2019-04-08 18:42:53.020 20591-20591/com.app E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.app, PID: 20591
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getDatabasePath(java.lang.String)' on a null object reference
        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:292)
        at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:262)
        at com.app.SQLiteAdaptor.GetUserByUserId(SQLiteAdaptor.java:99)
        at com.app.OrderHistory$1.onItemClick(OrderHistory.java:64)
        at android.widget.AdapterView.performItemClick(AdapterView.java:318)
        at android.widget.AbsListView.performItemClick(AbsListView.java:1181)
        at android.widget.AbsListView$PerformClick.run(AbsListView.java:3165)
        at android.widget.AbsListView$3.run(AbsListView.java:4147)
        at android.os.Handler.handleCallback(Handler.java:794)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:173)
        at android.app.ActivityThread.main(ActivityThread.java:6634)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:822)

This is where I need to retrieve row

 @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {


                final Dialog fullscreenDialog = new Dialog(getApplicationContext(), R.style.Dialog);
                    fullscreenDialog.setContentView(R.layout.dialog_oh);


                SQLiteAdaptor db = new SQLiteAdaptor(c);
                ArrayList<HashMap<String, String>> userList = db.GetUserByUserId(i); //Line 64
                HashMap<String, String> hashDetails = userList.get(0);

                     //Use this index accordingly
                    tvit.setText(hashDetails.get("item"));
                    tvpr.setText(hashDetails.get("price"));
                    tvqu.setText(hashDetails.get("quantity"));
                    tvad.setText(hashDetails.get("address"));
                    tvna.setText(hashDetails.get("name"));
                    tvem.setText(hashDetails.get("email"));
                    tvtim.setText(hashDetails.get("time"));

fullscreenDialog.show();
}
});

Here is the SQLiteAdaptor get row data by id method snippet

 public ArrayList<HashMap<String, String>> GetUserByUserId(int userid ){
        SQLiteDatabase db = this.getReadableDatabase(); \\Line 99
        ArrayList<HashMap<String, String>> userList = new ArrayList<>();
        String  query = "SELECT item, price, quantity, name, address, email, orderid FROM "+ Table_Name;

        Cursor cursor = db.query(Table_Name, new String[]{COL_2, COL_3, COL_4, COL_5, COL_6, COL_7, COL_8, COL_9}, COL_1+ "=?",new String[]{String.valueOf(userid)},null, null, null, null);
        if (cursor.moveToNext()){
            HashMap<String,String> user = new HashMap<>();
            user.put("item",cursor.getString(cursor.getColumnIndex(COL_2)));
            user.put("price",cursor.getString(cursor.getColumnIndex(COL_3)));
            user.put("quantity",cursor.getString(cursor.getColumnIndex(COL_4)));
            user.put("name",cursor.getString(cursor.getColumnIndex(COL_5)));
            user.put("address",cursor.getString(cursor.getColumnIndex(COL_6)));
            user.put("email",cursor.getString(cursor.getColumnIndex(COL_7)));
            user.put("orderid",cursor.getString(cursor.getColumnIndex(COL_8)));
            user.put("time",cursor.getString(cursor.getColumnIndex(COL_9)));
            userList.add(user);
        }
        return  userList;
    }

And it is not null pointer exception because I am nit getting any error while retrieving data in Listview

Or any other way to how to retrieve row with its id

Any help and solutions are appreciated

Thanks in advance

Answer 1

尝试

SQLiteAdaptor db = new SQLiteAdaptor(view.getContext());