Android 9 Development Cookbook - Third Edition

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In this recipe, we are monitoring the Call State events, as indicated with this constant: LISTEN_CALL_STATE. The other interesting options include the following:

• LISTEN_CALL_FORWARDING_INDICATOR
• LISTEN_DATA_CONNECTION_STATE
• LISTEN_SIGNAL_STRENGTHS

Take a look at the PhoneStateListener link in See also for a complete list.

When we're done listening for events, call the listen() method and pass LISTEN_NONE, as shown here:

telephonyManager.listen(mPhoneStateListener,PhoneStateListener.LISTEN_NONE);