How to pass array list to background worker.

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I need to pass one arraylist 'searchtext' and another arraylist of arraylists str[] to the backgroundworker1_DoWork and then perform operations on them. Please help. Stuff on other websites were very unclear. A link to a webpage explaining this concept in a simple fashion is also appreciated.

Posted 16-Oct-14 8:03am

Tejas Shastri

Updated 16-Oct-14 8:49am

v3

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Kornfeld Eliyahu Peter 16-Oct-14 14:21pm

http://mattgemmell.com/what-have-you-tried/

Tejas Shastri 16-Oct-14 14:48pm

Haha... I'm sorry.. I expected more similar replies though.. I haven't tried because I have no clue as to how.. I would appreciate a link which deals with this concept.. Thank you..

BillWoodruff 16-Oct-14 14:36pm

Why are you using an ArrayList instead of using strongly typed generic Lists ?

Tejas Shastri 16-Oct-14 14:44pm

I'm a newbie.. I'm using stuff I'm comfortable with.. Lot to learn..

BillWoodruff 16-Oct-14 14:51pm

It's very easy to use Generic Lists like List<string> and your code will be much faster than using ArrayLists. If you were my student, I would expect you to understand generic lists before I would expect you understood using BackGroundWorker :)

ArrayLists are an outmoded object Type from the early versions of .NET. If you need to pass a Collection that contains mixed Types of objects, the typical solution is to define a Class or a Struct and pass a collection of those.

Tejas Shastri 16-Oct-14 14:58pm

well the problem is I'm a student of the Internet and I'm trying to learn C# by building an app using C#.. So I'm learning each concept as and when it is necessary.. when I used ArrayList I didn't know there was generic list.. Please forgive my ignorance. :_ )

BillWoodruff 16-Oct-14 15:09pm

There's no ignorance here to forgive :) We all were "new" once and learning-as-you-go by building an app is a good way to learn. I strongly suggest you combine building-the-app and hands-on programming with language study with a good book, or on-line materials. For most students I've had it is the combination of those modes of learning that really pays off, and, if you have a teacher available, or peers you can work with who are a little further along than you are, that's really great.

Do remember that for almost any given task, or code problem, there are resources available via the web. For example, I suggest you:

1. start (of course) with searching CodeProject:

"BackgroundWorker Class Sample for Beginners" http://www.codeproject.com/Articles/99143/BackgroundWorker-Class-Sample-for-Beginners

2. read the top four links here:

https://www.google.com/search?q=c%23%20understanding%20backgroundworker

cheers, Bill

Tejas Shastri 16-Oct-14 15:11pm

Thank you for the advice. :) but please suggest a good book on your mind. Thanks

BillWoodruff 16-Oct-14 15:57pm

If you have a good background in some other programming language, and object-oriented development, or C/C++ I'd recommend any of Jon Skeet's books on C#, or books by Andrew Troelsen. If C# is your first language, I'd recommend books by Jesse Liberty, Matthew MacDonald, Joseph Albihari. My first pick for a newcomer would be:

http://www.amazon.com/Learning-C-3-0-Jesse-Liberty/dp/0596521065/ref=la_B000APP6I6_1_5?s=books&ie=UTF8&qid=1413489389&sr=1-5

Even though it was published five years ago, I think it's still excellent.

3 solutions

Solution 3

Instead of using BackgroundWorker, you can create a thread explicitly (using a constructor) and reuse it as needed.

The problem if data exchange with other thread is solved nicely using the conception of thread wrapper I introduced:
How to pass ref parameter to the thread[^],
Change parameters of thread (producer) after it is started[^],
MultiThreading in C#[^].

This way, you can hide thread synchronization detail inside a wrapper; beside, you pass its instance "this" at initialization.

This is how you can reuse the thread of the wrapper:
Making Code Thread Safe[^],
Running exactly one job/thread/process in webservice that will never get terminated (asp.net)[^].

(You can find some related ideas in my past answers referenced above.)

—SA

Posted 16-Oct-14 10:30am

Sergey Alexandrovich Kryukov

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Richard Deeming · Accepted Answer · 2014-10-16T08:24:00

It's quite simple:

Pass the state object to the RunWorkerAsync method;
In the DoWork event handler, you are passed an instance of the DoWorkEventArgs class. Whatever object you passed as the state to the RunWorkerAsync method is available from the Argument property.
Since the Argument property is an object, you'll need to cast it to the type you passed in.

Example:

C#

private sealed class BackgroundWorkState
{
    public List<string> List1 { get; set; }
    public List<MyClass> List2 { get; set; }
    public string SomethingElse { get; set; }
}

private void StartBackgroundWork()
{
    BackgroundWorkState workerState= new BackgroundWorkState
    {
        List1 = ...,
        List2 = ...,
        SomethingElse = ...,
    };
    
    backgroundWorker.RunWorkerAsync(workerState);
}

private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorkState myState = (BackgroundWorkState)e.Argument;
    // The myState variable is now the same object you passed to the RunWorkerAsync method.
    ...
}

OriginalGriff · Accepted Answer · 2014-10-16T08:21:00

Solution 1

You pass it to the DoWorkAsync method, and retrieve it from the eventargs:

C#

    List<string> list = new List<string>(){"hello", "Goodbye"};
    BackgroundWorker worker = new BackgroundWorker();
    worker.DoWork += new DoWorkEventHandler(worker_DoWork);
    worker.RunWorkerAsync(list);
    ...
    }

void worker_DoWork(object sender, DoWorkEventArgs e)
    {
    object o = e.Argument;
    List<string> list = o as List<string>;
    if (list != null)
        {
        ...
        }

Posted 16-Oct-14 8:21am

OriginalGriff

Comments

Tejas Shastri 16-Oct-14 14:27pm

I have to pass one array list and another array list of array lists(ArrayList[] str= new arraylist[];) kind

OriginalGriff 16-Oct-14 14:39pm

No, you can only pass one object to the RunWorkerAsync method: so create a "helper class" which contains the info the worker is to process and pass an instance of that instead. (It also saves on casting in the DoWork handler)