如何在主活动中监听BroadcastReceiver？

public class MainActivity extends AppCompatActivity {
    private BroadcastReceiver receiver;

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

        // 创建BroadcastReceiver实例
        receiver = new MyBroadcastReceiver();

        // 注册BroadcastReceiver
        IntentFilter filter = new IntentFilter();
        filter.addAction("com.example.ACTION_MY_BROADCAST");
        registerReceiver(receiver, filter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        // 注册BroadcastReceiver
        IntentFilter filter = new IntentFilter();
        filter.addAction("com.example.ACTION_MY_BROADCAST");
        registerReceiver(receiver, filter);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // 取消注册BroadcastReceiver
        unregisterReceiver(receiver);
    }

    private class MyBroadcastReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            // 处理接收到的广播事件
            String message = intent.getStringExtra("message");
            Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
        }
    }
}