Question

我最近开始使用retrolambda库来支持Android开发中的lambda，我从Android Studio收到以下警告：

可以用收集电话代替。

此检查报告foreach循环，可以用流api调用替换。

我的代码如下：

// mGeofenceList is a List<Geofence>
mGeofenceList = new ArrayList<>();
    // GeofenceUtils.GeofenceObjects.entrySet() is a HashMap<String, LatLng>
    for (Map.Entry<String, LatLng> entry : GeofenceUtils.GeofenceObjects.entrySet()) {
        mGeofenceList.add(new Geofence.Builder()
                .setRequestId(entry.getKey())
                .setCircularRegion(
                        entry.getValue().latitude,
                        entry.getValue().longitude,
                        GeofenceUtils.GEOFENCE_RADIUS_IN_METERS)
                .setExpirationDuration(GeofenceUtils.GEOFENCE_EXPIRATION_IN_MILLISECONDS)
                .setTransitionTypes(Geofence.GEOFENCE_TRANSITION_ENTER |
                        Geofence.GEOFENCE_TRANSITION_EXIT)
                .build());
    }

问题：如何将其替换为收集电话？

更新：当我按下alt +时，将其转换为以下代码：

// method stream() cannot be found    
mGeofenceList.addAll(GeofenceUtils.GeofenceObjects.entrySet().stream()
            .map(entry -> new Geofence.Builder()
            .setRequestId(entry.getKey())
            .setCircularRegion(
                    entry.getValue().latitude,
                    entry.getValue().longitude,
                    GeofenceUtils.GEOFENCE_RADIUS_IN_METERS)
            .setExpirationDuration(GeofenceUtils.GEOFENCE_EXPIRATION_IN_MILLISECONDS)
            .setTransitionTypes(Geofence.GEOFENCE_TRANSITION_ENTER |
                    Geofence.GEOFENCE_TRANSITION_EXIT)
            // Collectors cannot be found
            .build()).collect(java.util.stream.Collectors.toList()));

现在它说它无法解析方法流（），收集器。它可以修复吗？我可以添加一些import语句吗？或者目前它不受retrolambda的支持？

更新：已解决，请参阅下面的答案。

Answer 1

感谢所有评论此问题的人。在此库的帮助下解决了问题：https://github.com/aNNiMON/Lightweight-Stream-API

Stream.of（YourCollection）在Java 8实现中，您将看到YourCollection.stream（...）。无论哪种方式，都会创建一个Stream实例。

此库的最终工作代码：

df <- data.frame(datetime=c('1/1/2015 0:00','1/1/2015 0:01','1/1/2015 0:02','1/1/2015 0:03','1/1/2015 0:04','1/1/2015 0:05','1/1/2015 0:06','1/1/2015 0:07','1/1/2015 0:08','1/1/2015 0:09','1/1/2015 0:10','1/1/2015 0:11','1/1/2015 0:12','1/1/2015 0:13','1/1/2015 0:14','1/1/2015 0:15','1/1/2015 0:16','1/1/2015 0:17'),alarm=c('NO','NO','NO','NO','NO','NO','NO','NO','NO','NO','YES','NO','NO','NO','YES','NO','NO','NO'),stringsAsFactors=F);
df$datetime <- as.POSIXct(df$datetime,'%d/%m/%Y %H:%M',tz='UTC');
w <- which(df$alarm=='YES');
df$diff <- difftime(df$datetime,df$datetime[c(1L,w)[findInterval(seq_along(df$alarm),w)+1L]],units='hours');
df;
##               datetime alarm             diff
## 1  2015-01-01 00:00:00    NO 0.00000000 hours
## 2  2015-01-01 00:01:00    NO 0.01666667 hours
## 3  2015-01-01 00:02:00    NO 0.03333333 hours
## 4  2015-01-01 00:03:00    NO 0.05000000 hours
## 5  2015-01-01 00:04:00    NO 0.06666667 hours
## 6  2015-01-01 00:05:00    NO 0.08333333 hours
## 7  2015-01-01 00:06:00    NO 0.10000000 hours
## 8  2015-01-01 00:07:00    NO 0.11666667 hours
## 9  2015-01-01 00:08:00    NO 0.13333333 hours
## 10 2015-01-01 00:09:00    NO 0.15000000 hours
## 11 2015-01-01 00:10:00   YES 0.00000000 hours
## 12 2015-01-01 00:11:00    NO 0.01666667 hours
## 13 2015-01-01 00:12:00    NO 0.03333333 hours
## 14 2015-01-01 00:13:00    NO 0.05000000 hours
## 15 2015-01-01 00:14:00   YES 0.00000000 hours
## 16 2015-01-01 00:15:00    NO 0.01666667 hours
## 17 2015-01-01 00:16:00    NO 0.03333333 hours
## 18 2015-01-01 00:17:00    NO 0.05000000 hours

Android Studio中的警告：可以使用collect调用替换

1 个答案: