Question

我有一个有很多静态方便方法的类。其中一个应该动态启动BroadcastReceiver - 但它总是返回一个InstantiationException。 BroadcastReceiver有一个无参数的构造函数，所以它应该工作 - 但事实并非如此。这是我到目前为止所做的：

以下是该课程中的便捷方法：

// Static convenience methods in a tools class
public class MyTools {

    // Start BroadcastReceiver dynamically
    public static BroadcastReceiver startBroadcastReceiver(Context context,
            Class<? extends BroadcastReceiver> receiverClass, String receiverTag) {

        BroadcastReceiver receiver = null;

        try {
            receiver = (BroadcastReceiver) receiverClass.newInstance();
            if (receiver != null) {
                IntentFilter intentFilter = new IntentFilter(receiverTag);
                if (intentFilter != null) {
                    context.registerReceiver(receiver, intentFilter);
                }
            }
        } catch (Exception exception) {
            // --> InstantiationException
        }

        return receiver;
    }

    // ...
}

这是一个使用InnerClass BroadcastReceiver的活动，尝试使用这种方便的方法启动BroadcastReceiver：

// An activity with an InnerClass BroadcastReceiver
public class MyActivity extends Activity {

    public class MyBroadcastReceiver extends BroadcastReceiver {

        public static final String TAG = "aa.bb.cc.MyActivity.MyBroadcastReceiver";

        public static final long ACTION_UNDEFINED = 0;
        public static final long ACTION_DOSOMETHING = 1;

        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent != null) {
                Bundle bundleExtras = intent.getExtras();
                if (bundleExtras != null) {
                    long action = bundleExtras.getLong("ACTION");
                    if (action == ACTION_DOSOMETHING) {
                        doSomething();
                    }
                }
            }
        }
    }

    private MyBroadcastReceiver receiver;

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

        // Start BroadcastReceiver
        receiver = (MyBroadcastReceiver) MyTools.startBroadcastReceiver(this,
                MyBroadcastReceiver.class, MyBroadcastReceiver.TAG);
    }


    public void doSomething() {
        // ...
    }
}

这种方法有什么问题？

非常感谢任何帮助。

Answer 1

这就是问题

让广播接收器成为静态内部类 public static class MyBroadcastReceiver扩展BroadcastReceiver

或在自己的文件中声明

实例化异常中没有空构造函数的混乱可能会令人困惑

在BroadcastReceiver上使用newInstance时出现InstantiationException

1 个答案: