使用方法引用定义 BroadcastReceiver.onReceive

Question

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);

不幸的是，这是不可能的。虽然onReceive()是BroadcastReceiver唯一的抽象方法，但那个东西不是接口，而是抽象class，它们似乎不能被 lambda 表达式替换。有什么解决这个问题的建议吗？

Answer 1

使用中概述的技巧，我得到：

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);
    }
}

没有我想象的那么简洁，但是更好：

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

Answer 2

只是为了扩展上面的答案，没有 BiConsumer（在 API<24 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);
    }
}

然后，同上或下

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

使用方法引用定义 BroadcastReceiver.onReceive

Define BroadcastReceiver.onReceive with a method reference

java

lambda

android

java-8

android-7.0-nougat