Question

我有2个地图。

HashMap<DedupeTableEntity,List<DedupeTableEntity>> deltaHashmap 

HashMap<DedupeTableEntity,List<DedupeTableEntity>> existingHashmap

残疾者具有id、国家、实体。

I want to iterate through the values of delta hash map (both hashmaps has only 1 key and list of values under that key)
Check whether that object is in existing hash map if 2 attributes match (country and id)
如果有

Take attribute value of (entity flag) that object from existinghashmap and replace the attribute (entity flag) value of the same object in the delta hash map

public void compareTwoHashmaps(HashMap<DedupeTableEntity,List<DedupeTableEntity>> deltaHashmap 
, HashMap<DedupeTableEntity,List<DedupeTableEntity>> existingHashmap){
        //iterate through deltahashmap values
        return deltaHashmap.values().stream()
                .flatMap(Collection::stream)
                .filter(c -> (existingHashmap.values().stream().flatMap(Collection::stream).filter(e->e.getId().equals(c.getId()) && e.getObjectCountry().equals(c.getObjectCountry())))
                        .map(k-> k.setEntityFlag(existingHashmap.values().stream().flatMap(Collection::stream).filter(e->e.getId().equals(k.getId()) && e.getObjectCountry().equals(k.getObjectCountry())).map(r ->r.getEntityFlag()).toString()));
    }

这是我迄今为止所走过的。但有一个错误,即:如何纠正。

希望得到任何帮助。

Answer 1

Performing a linear scan through existingHashmap for every element in deltaHashmap is extremely wasteful.
map is not for performing an action on each element in a Stream. map is for changing the element returned in a Stream. For performing an action, you should use forEach.
Calling toString() on a Stream is unlikely to produce useful information.

我首先将绘制以下图,即用于配对财产的<代码>现有HashMap的数值。易于执行复合钥匙的方法是界定一个。班级。绘制这种地图时,可进行对比,可以更快地寻找对应物,而不必检查现有的Hashmap在德尔塔哈什图中的每一价值。 (校对班自动界定平等、传统和根据成员制定方法)。

不应在此加以利用,因为它具有价值——但是没有回报的价值。你们正在某个实体中设定财产。这样做不会归还任何东西。

public void compareTwoHashmaps(
    HashMap<DedupeTableEntity,List<DedupeTableEntity>> deltaHashmap,
    HashMap<DedupeTableEntity,List<DedupeTableEntity>> existingHashmap) {

    record Identifiers(String id, String country) {
        static Identifiers of(DedupeTableEntity entity) {
            return new Identifiers(entity.getId(),
                                   entity.getObjectCountry());
        }
    }

    Map<Identifiers, DedupeTableEntity> allExisting =
        existingHashmap.values().stream().flatMap(Collection::stream)
            .collect(Collectors.toMap(Identifiers::of, e -> e));

    deltaHashmap.values().stream().flatMap(Collection::stream)
        .forEach(delta -> {
            DedupeTableEntity existing =
                allExisting.get(Identifiers.of(delta));

            if (existing != null) {
                delta.setEntityFlag(existing.getEntityFlag());
            }
        });
}

Answer 2

似乎在流体中存在一些不正确的母体。还有一些可能的重复守则,我试图减少。我也做了一些开采,最后是:

public void updateFlag(
        Map<DedupeTableEntity, List<DedupeTableEntity>> deltaHashmap,
        Map<DedupeTableEntity, List<DedupeTableEntity>> existingHashmap
) {
    deltaHashmap.values().stream()
            .flatMap(Collection::stream)
            .forEach(k -> extractFlag(existingHashmap, k)
                    .ifPresent(k::setEntityFlag));
}

private Optional<String> extractFlag(Map<DedupeTableEntity, List<DedupeTableEntity>> existingHashmap, DedupeTableEntity k) {
    return existingHashmap.values().stream()
            .flatMap(Collection::stream)
            .filter(e -> equalsByIdAndCountry(k, e))
            .findFirst().map(DedupeTableEntity::getEntityFlag);
}

private boolean equalsByIdAndCountry(DedupeTableEntity c, DedupeTableEntity e) {
    return e.getId().equals(c.getId()) && e.getObjectCountry().equals(c.getObjectCountry());
}

如果数据确实正确,我就没有任何数据可以检测,因此我留给你。

Answer 3

你的法典有一些错误:

The method has a return type of void, but it attempts to return a stream.
The call to map on the filter operation is not terminal, meaning that it won t actually execute the mapping operation.
To fix these issues, the method could be modified to return the modified deltaHashmap

a 固定版本,包括返回表:

public HashMap<DedupeTableEntity,List<DedupeTableEntity>> compareTwoHashmaps(
    HashMap<DedupeTableEntity,List<DedupeTableEntity>> deltaHashmap,
    HashMap<DedupeTableEntity,List<DedupeTableEntity>> existingHashmap) {
deltaHashmap.values().stream()
        .flatMap(Collection::stream)
        .filter(c -> existingHashmap.values().stream()
                .flatMap(Collection::stream)
                .anyMatch(e -> e.getId().equals(c.getId()) && e.getObjectCountry().equals(c.getObjectCountry())))
        .forEach(k -> {
            Optional<String> entityFlag = existingHashmap.values().stream()
                    .flatMap(Collection::stream)
                    .filter(e -> e.getId().equals(k.getId()) && e.getObjectCountry().equals(k.getObjectCountry()))
                    .map(r -> r.getEntityFlag())
                    .findFirst();
            entityFlag.ifPresent(k::setEntityFlag);
        });
return deltaHashmap;
}

友情链接