CODEWITHSUNDEEP
androidtoast
j-maas
j-maas

Reputation: 906

Preventing Toasts from queueing up

When my app starts up, but has not yet loaded a file, the user gets a Toast when he clicks the button. It takes about half a second to load, so since he is able to click the button multiple times, it is possible for multiple Toasts to get displayed after one another.

I tried setting up a Toast object as an attribute of my MainActivity's class, but it crashes with NullPointerExceptions.
The implementation:

Toast lToast;
(...)
public void exampleMethod() {
    if(lToast == null) {
        lToast.makeText(this, "Noch kein Sound geladen.", Toast.LENGTH_SHORT);
        lToast.show();
    }
}

Is it possible to prevent Toasts from queueing up without the need to have a local attribute? And if not, what did I do wrong?

Upvotes: 1

Views: 740

Answers (4)

CodeWarrior
CodeWarrior

Reputation: 5176

WIIIJBD has given a wonderful answer.

However in your case instead of blocking the Toast you can disable the Button.

You can disable the button in onClick() and then again set your onClickListener() somewhere when you get your callback after you are done loading whatever you intend to load.

Upvotes: 1

WIllJBD
WIllJBD

Reputation: 6164

I am not sure what you mean by "without a local attribute", but digging in to the android code you will find that the long and short delays are as follows

private static final int LONG_DELAY = 3500; // 3.5 seconds
private static final int SHORT_DELAY = 2000; // 2 seconds

so when you launch your toast, if you capture the timestamp like so

long lastToastTimestamp = System.currentTimeMillis();

you should be able to prevent multiple toast messages

if (System.currentTimeMillis() - lastToastTimestamp > 2000)
{
   lastToastTimestamp = System.currentTimeMillis();
   Toast.makeText(this, "Noch kein Sound geladen.", Toast.LENGTH_SHORT).show();
}

or what about this

make the field:

Toast mToast = null;

and then the code:

if (mToast == null)
{
    mToast = Toast.makeText(context, "Noch kein Sound geladen.", Toast.LENGTH_SHORT);
    mToast.show();
    new Handler().postDelayed(new Runnable() {

        @Override
        public void run()
        {
            mToast = null;
        }
    }, 2000);
}

If you wanted to make it even more complex you could create your own queue, and only insert new toasts that will be displayed at the expiration of the previous one, if the text given the toast is different from the current one and all the ones in the queue.

Upvotes: 3

Leonardo
Leonardo

Reputation: 3191

I know that your question wasn't that but anyway... A library I use and recommend using is Crouton, which is a Activity strong-dependent library just like Toast, with a lot of customization !

Hope it helps !

Upvotes: 0

Than
Than

Reputation: 2769

Toast.makeText(...) is static member of Toast class returning Toast instance. You've declared Toast lToast object but you didnt initialize it.

Change:

lToast.makeText(this, "Noch kein Sound geladen.", Toast.LENGTH_SHORT);

to

lToast = Toast.makeText(this, "Noch kein Sound geladen.", Toast.LENGTH_SHORT);

I'm not sure if this will work, but it will prevent raising NullPointerException.

Upvotes: 2

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