How I can do this more better using lambda?

user_1324172 0
Viewed 124

I don't like section with forEach, but I wouldn't know how to do this better with lambda.

list1.stream().map(element -> {
    list2.forEach(item -> {
       if (element.getKey().equals(item.getKeyNextYear())) {
          element.setSummPreviosYear(item.getSumm());
          element.setCashboxCountPreviosYear(item.getCashboxCount());
          element.setCheckCountPreviosYear(item.getCheckCount());
          element.setArticleCountPreviosYear(item.getArticleCount());
       }
    });
    return element;
}).collect(Collectors.toList());
java-8 java
2 Answers

You can simplify this a lot by removing the outer stream and doing the inner part with a filter().findAny() search. This also prevents re-setting the properties in case multiple items in list2 match the element.

list1.forEach(element ->
                list2.stream()
                     .filter(item -> element.getKey().equals(item.getKeyNextYear()))
                     .findAny()
                     .ifPresent(item -> {
                         element.setSummPreviosYear(item.getSumm());
                         element.setCashboxCountPreviosYear(item.getCashboxCount());
                         element.setCheckCountPreviosYear(item.getCheckCount());
                         element.setArticleCountPreviosYear(item.getArticleCount());
                     }));

There is no need to stream list1 and collect it into a new list, at least it isn't clear from your sample code. The original list will still contain the same elements as the new one, including the changed properties.

user_76530730

To remove 'if' - statement you can use filter first:

list2.filter(item -> element.getKey().equals(item.getKeyNextYear())).forEach(...)

And, I think, It's better to move setters to new method

user_67034490
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