初学 Android,请问下这段监听网络变化的代码在 Android 11 如何变得有效？

我是在教程看到的，但是我在 Android 11 上发现不起作用了,没有报错，但是也没有达到预期的效果

public class MainActivity extends AppCompatActivity {
    NetReceiver netReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        netReceiver = new NetReceiver();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("android.net.CONNECTIVITY_CHANGE");
        registerReceiver(netReceiver,intentFilter);

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(netReceiver);
    }

    public class NetReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(context,"网络发生变化",Toast.LENGTH_LONG).show();
             Log.e("mylog","网络发生变化");
        }
    }
}

我尝试在 AndroidManifest.xml 中添加权限,也是没有效果

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />