Inside OnClickListener I cannot access a lot of things - how to approach?

Question

Inside an OnClickListener I cannot access most variables "outside" of the scope, like this:

findViewById(R.id.Button01).setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Intent mainApps = new Intent(Intent.ACTION_MAIN);
                mainApps.addCategory(Intent.CATEGORY_LAUNCHER);
                List<ActivityInfo> activities = this.getPackageManager().queryIntentActivities(mainApps, 0);
                /*
                Intent intent = new Intent("com.sygic.drive/com.sygic/drive/.SygicDriveActivity");
                startActivity(intent);*/
            }

        });

in this example I need to get the PacketManager, and I cannot get it since I do not have the Context available inside the OnClickListener.

I could make a static reference outside, and use it inside, but is that correct? Seems odd to have to do that all the time?

Answer 1

There are a few things you can do, you can create an inner class that implements the onClickListener and pass the necessary arguments into the constructor of the class. I still don't find that the cleanest approach. I usually just create another method to perform my action. So in the onClick(View v) I would do something like this.

onClick(View v){doMyAction(myParams)}

private void doMyAction(Object params){//do stuff}

And just pass the needed params from the listener method to the method outside the listener.

Answer 2

Replace "this" in your code with "MyActivity.this" where MyActivity is the class name of your Activity subclass.

Explanation: You are creating an anonymous inner class when you use this part of your code: "new OnClickListener() {". Anonymous inner classes have a reference to the instance of the class they are created in. It looks like you are creating it inside an Activity subclass because findViewById is an Activity method. Activity's are a Context, so all you need to do is use the reference to it that you have automatically.

Answer 3

You could also implement the OnClickListener interface in your class and avoid the need for an anonymous inner class. Then you would set the on click listener like this:

findViewById(R.id.Button01).setOnClickListener(this);

If you have multiple buttons using one listener, you can use a switch statement with view.getId() (which corresponds to the view's id in R.id) to distinguish between them.