使用方法引用定义BroadcastReceiver.onReceive

Posted 2021-05-05

使用Jack支持Java 8，我希望能够写出类似的东西：

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的独特抽象方法，但该东西不是一个接口，它是一个抽象类，看起来似乎不能被lambda表达式替换。有什么建议可以解决这个问题吗？

答案

使用this answer中概述的技巧，这是我得到的：

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);
    }
}

不像我预期的那样简洁，但更好：

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

另一答案

只是为了扩展上面的答案，没有BiConsumer（不适用于API <24）

interface IBR {
    void onReceive(Context context, Intent intent);
}

class BroadcastReceiver extends android.content.BroadcastReceiver {
    private final IBR receiver;

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

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