使用方法参考定义 BroadcastReceiver.onReceive答案

【问题标题】：Define BroadcastReceiver.onReceive with a method reference使用方法参考定义 BroadcastReceiver.onReceive
【发布时间】：2016-11-25 08:51:25
【问题描述】：

使用 Jack 对 Java 8 的支持，我希望能够编写类似的东西：

public void onReceive(Context context, Intent intent) {
    if (!intent.getAction().equals(ACTION_BINGO)) return;
    Log.d(TAG, "Bingo!");
}

... 

registerReceiver(this::onReceive, INTENT_FILTER_BINGO);

很遗憾，这是不可能的。虽然onReceive() 是BroadcastReceiver 独有的抽象方法，但那东西不是接口，它是一个抽象类，似乎不能被lambda 替换表达式。有什么建议可以解决这个问题？

【问题讨论】：

您可以为扩展 BroadcastReceiver 的类创建构造函数，并将接口侦听器传递给该构造函数。在 onReceive 方法中调用监听器
我几乎得出了同样的结论，只是我没有使用监听器。

标签： java android lambda java-8 android-7.0-nougat

【解决方案1】：

使用this answer 中概述的技巧，我得到了：

public class BroadcastReceiver extends android.content.BroadcastReceiver {

    private final BiConsumer<Context, Intent> receiver;

    public BroadcastReceiver(final BiConsumer<Context, Intent> onReceive) {
        receiver = onReceive;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        if (receiver == null) {
            throw new UnsupportedOperationException("Not yet implemented");
        }
        receiver.accept(context, intent);
    }
}

没有我预期的那么简洁，但更好：

BroadcastReceiver receiver = new BroadcastReceiver(this::onReceive);
registerReceiver(receiver, INTENT_FILTER_BINGO);

【讨论】：

【解决方案2】：

只是为了扩展上面的答案，没有 BiConsumer（API 中不可用

class BroadcastReceiver extends android.content.BroadcastReceiver {
    public interface IBR {
        void onReceive(Context context, Intent intent);
    }

    private final IBR receiver;

    public BroadcastReceiver( IBR receiver ){
        this.receiver = receiver;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        receiver.onReceive(context, intent);
    }
}

那么，同上同下

BroadcastReceiver receiver = new BroadcastReceiver(this::onReceive);
registerReceiver(receiver, INTENT_FILTER_BINGO);

【讨论】：