java - 更改 Activity 时如何停止 PhoneStateListener

Question

我在 Activity 中定义了一个 PhoneStateListener，我想在更改 Activity 时停止监听器。我已尝试使用此代码来完成此操作，但它不起作用。

public class OriginActivity extends AppCompatActivity{
    private TelephonyManager tManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_origin);
        tManager = (TelephonyManager)getSystemService(TELEPHONY_SERVICE);
        tManager.listen(new CustomPhoneStateListener(this), PhoneStateListener.LISTEN_SIGNAL_STRENGTHS);
    }

    protected void onPause() {
        super.onPause();

        // Logs 'app deactivate' App Event.
        AppEventsLogger.deactivateApp(this);

       tManager.listen(new CustomPhoneStateListener(this), PhoneStateListener.LISTEN_NONE);
    }
}

我做错了什么？

Answer 1

我找到了解决办法!!!

public class OriginActivity extends AppCompatActivity{

    CustomPhoneStateListener customPhoneStateListener;

    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_origin);

        /**** Other Code ****/

    }

    protected void onResume() {
        super.onResume();

        //Here, we start the listener!!!
        TelephonyManager tManager = (TelephonyManager)getSystemService(TELEPHONY_SERVICE);
        customPhoneStateListener = new CustomPhoneStateListener(this);
        tManager.listen(customPhoneStateListener, PhoneStateListener.LISTEN_SIGNAL_STRENGTHS);
        Log.d(TAG, "onResume");
    }

    protected void onPause() {
        super.onPause();

        //Here, we stop the listener!!!
        TelephonyManager tManager = (TelephonyManager)getSystemService(TELEPHONY_SERVICE);
        tManager.listen(customPhoneStateListener, PhoneStateListener.LISTEN_NONE);
        customPhoneStateListener = null;
    }

}

因此，当我们第一次访问 Activity 或从另一个 Activity 返回时，我们调用 onResume() 并启动监听器。而且，当我们使用 onPause() 退出 Activity 时，我们会停止监听器。