Java 如何在更改活动时停止PhoneStateListener

我在活动中定义了PhoneStateListener，并希望在更改活动时停止侦听器。我试着用这段代码来实现它，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);
    }
}

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我做错了什么

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，当我们第一次访问该活动或从另一个活动返回时，我们调用onResume（）并启动侦听器。当我们使用onPause（）退出活动时，我们会停止侦听器。

可以在服务因某种原因停止时完成（比如用户单击停止按钮）

@Override
public void onDestroy() {
    super.onDestroy();
    telephonyManager.listen(listener, PhoneStateListener.LISTEN_NONE);
    listener = null;
}