How to get switch value in Android?

Question

I have placed a switch widget in Main Activity, I also have a second activity that extends BroadcastReceiver. I want to get the boolean state of switch widget in second activity.

If I type

Switch s = (Switch) findViewById(R.id.switch1);

it says findViewById is undefined for the type SecondActivity. The problem is Android doesn't allow me to get the value of switch in a class that extends Broadcast Receiver.

I want to know the state of switch, i.e, whether switch is on or off, but in second activity. How can I achieve it?

Answer 1

Calling findViewById() from an Activity can only access Views that are a part of the layout of that Activity. You cannot use it to search the layout of any other Activity.

Depending on your app design, you can use one of these:

1) Send the value of the Switch to SecondActivity via an Intent extra

In Activity:

Intent mIntent = new Intent(this, SecondActivity.class);
mIntent.putExtra("switch", s.isChecked());
startActivity(mIntent);

In SecondActivity:

boolean isChecked = getIntent().getBooleanExtra("switch", false);

2) Save the value to a preference on change, and read preferences in SecondActivity

In Activity:

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor e = settings.edit();
e.putBoolean("switch", s.isChecked());
e.commit();

In SecondActivity:

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
boolean isChecked = settings.getBoolean("switch", false);