Error #1009: Cannot access a property or method of a null object reference. when using sqlite

问题

I'm using sqlite in flash but I get this error: Error #1009: Cannot access a property or method of a null object reference. I have debuged it and this says it is on line 86 and 100 :

stat.text = "UPDATE contacts SET fname=@fname, lname=@lname, phone=@phone WHERE id=" + itemList.selectedItem.data.id;

and

stat.text = "DELETE FROM contacts WHERE id=" + itemList.selectedItem.data.id;

whole code:

import flash.filesystem.File;
import flash.data.SQLConnection;
import flash.data.SQLStatement;
import flash.net.Responder;
import flash.data.SQLResult;
import fl.data.DataProvider;
import flash.data.SQLMode;
import flash.errors.SQLError;
import flash.events.SQLErrorEvent;
import flash.events.SQLEvent;

var connection:SQLConnection;

openDatabase();
t_phone.restrict = "0-9";

function openDatabase():void
{
var dbFile:File = File.applicationStorageDirectory.resolvePath("database.db");
connection = new SQLConnection();
connection.addEventListener(SQLEvent.OPEN, onOpen);
connection.openAsync(dbFile, SQLMode.CREATE);
}

function onOpen(SQLEvent):void
{
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = connection;
stat.text = "CREATE TABLE IF NOT EXISTS contacts (id INTEGER PRIMARY KEY AUTOINCREMENT, fname TEXT, lname TEXT, phone INTEGER)";
stat.execute(-1, new Responder(selectItems));
}

function selectItems(SQLEvent):void
{
b_save.enabled = false;
b_delete.enabled = false;
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = connection;
stat.text = "SELECT id, fname, lname, phone FROM contacts ORDER BY id";
stat.execute(-1, new Responder(onSelected));
}

function onSelected(evt:SQLResult):void
{
if (evt.data != null)
{
var itemList:DataProvider = new DataProvider();
for (var i:int=0; i<evt.data.length; i++)
{
itemList.addItem({label:(evt.data[i].fname + " " + evt.data[i].lname), data:evt.data[i]});
}
}
}

b_new.addEventListener(MouseEvent.CLICK, createNew);

function createNew(MouseEvent):void
{
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = connection;
stat.text = "INSERT INTO contacts (fname, lname, phone) VALUES (@fname, @lname, @phone)";
stat.parameters["@fname"] = t_fname.text;
stat.parameters["@lname"] = t_lname.text;
stat.parameters["@phone"] = t_phone.text;
stat.execute(-1, new Responder(selectItems));
t_fname.text = t_lname.text = t_phone.text = "";
}

itemList.addEventListener(Event.CHANGE, onChange);

function onChange(evt:Event):void
{
b_save.enabled = true;
b_delete.enabled = true;
t_fname.text = evt.target.selectedItem.data.fname;
t_lname.text = evt.target.selectedItem.data.lname;
t_phone.text = evt.target.selectedItem.data.phone;
}

b_save.addEventListener(MouseEvent.CLICK, saveThis);

function saveThis(MouseEvent):void
{
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = connection;
stat.text = "UPDATE contacts SET fname=@fname, lname=@lname, phone=@phone WHERE id=" + itemList.selectedItem.data.id;
stat.parameters["@fname"] = t_fname.text;
stat.parameters["@lname"] = t_lname.text;
stat.parameters["@phone"] = t_phone.text;
stat.execute(-1, new Responder(selectItems));
t_fname.text = t_lname.text = t_phone.text = "";
}

b_delete.addEventListener(MouseEvent.CLICK, deleteThis);

function deleteThis(MouseEvent):void
{
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = connection;
stat.text = "DELETE FROM contacts WHERE id=" + itemList.selectedItem.data.id;
stat.execute(-1, new Responder(selectItems));
t_fname.text = t_lname.text = t_phone.text = "";
}

来源：https://stackoverflow.com/questions/19932304/error-1009-cannot-access-a-property-or-method-of-a-null-object-reference-when

标签

actionscript-3

flash

sqlite