How to handle screen orientation change when progress dialog and background thread active?

Question

My program does some network activity in a background thread. Before starting, it pops up a progress dialog. The dialog is dismissed on the handler. This all works fine, exc

Answer 1

I faced the same situation. What I did was get only one instance for my progress dialog in the entire application.

First, I created a DialogSingleton class to get only one instance (Singleton pattern)

public class DialogSingleton
{
    private static Dialog dialog;

    private static final Object mLock = new Object();
    private static DialogSingleton instance;

    private DialogSingleton()
    {

    }

    public static DialogSingleton GetInstance()
    {
        synchronized (mLock)
        {
            if(instance == null)
            {
                instance = new DialogSingleton();
            }

            return instance;
        }
    }

    public void DialogShow(Context context, String title)
    {
        if(!((Activity)context).isFinishing())
        {
            dialog = new ProgressDialog(context, 2);

            dialog.setCanceledOnTouchOutside(false);

            dialog.setTitle(title);

            dialog.show();
        }
    }

    public void DialogDismiss(Context context)
    {
        if(!((Activity)context).isFinishing() && dialog.isShowing())
        {
            dialog.dismiss();
        }
    }
}

As I show in this class, I have the progress dialog as attribute. Every time I need to show a progress dialog, I get the unique instance and create a new ProgressDialog.

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

When I am done with the background task, I call again the unique instance and dismiss its dialog.

DialogSingleton.GetInstance().DialogDismiss(this);

I save the background task status in my shared preferences. When I rotate the screen, I ask if I have a task running for this activity: (onCreate)

if(Boolean.parseBoolean(preference.GetValue(IS_TASK_NAME_EXECUTED_KEY, "boolean").toString()))
{
    DialogSingleton.GetInstance().DialogShow(this, "Checking credentials!");
} // preference object gets the info from shared preferences (my own implementation to get and put data to shared preferences) and IS_TASK_NAME_EXECUTED_KEY is the key to save this flag (flag to know if this activity has a background task already running).

When I start running a background task:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, true, "boolean");

DialogSingleton.GetInstance().DialogShow(this, "My title here!");

When I finish running a background task:

preference.AddValue(IS_TASK_NAME_EXECUTED_KEY, false, "boolean");

DialogSingleton.GetInstance().DialogDismiss(ActivityName.this);

I hope it helps.