Null check inside Java 8 streams forEach

Asked May 29 '16 at 18:41

Active May 29 '16 at 18:57

Viewed 2,905 times

I have the following code:

for (final String productId : entry.getValue()) {
    final Product pro = catalogAwareRepository.findUniqueByCatalogAndVersion(Constants.Id, productId, catalog, version, Product.class);
    if (pro != null) {
      productDTOs.add(productConverter.itemDTOfFromItem(product));
    }
}

I converted it to use Java 8 streams like this:

entry.getValue()
    .parallelStream()
    .map(productId -> catalogAwareRepository.findUniqueByCatalogAndVersion(Constants.Id, productId, catalog, version, Product.class))
    .forEach(pro -> productDTOs.add(productConverter.itemDTOfFromItem(pro)));

Is this the correct translation? Also, how do you perform a null check inside parallelStream operation?

Translation after Tunaki suggestion

entry.getValue().parallelStream().map(productId -> catalogAwareRepository.findUniqueByCatalogAndVersion(Constants.Id, productId, catalog, version, Product.class))
              .filter(Objects::nonNull).map(pro -> productDTOs.add(productConverter.itemDTOfFromItem(pro))).collect(Collectors.toList());

edited May 29 '16 at 18:57

asked May 29 '16 at 18:41

Saurabh Kumar

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1

Use filter function – Anton Shkurenko May 29 '16 at 18:44
2

You should also avoid `forEach`. Prefer to `collect` into a new list. – Tunaki May 29 '16 at 18:46
@Tunaki Thanks for your comments. How can i change my forEach to collectors ? – Saurabh Kumar May 29 '16 at 18:49
I suggest you to go through the Stream tutorial here: https://docs.oracle.com/javase/tutorial/collections/streams/. It'll teach you how to use a collector. – Tunaki May 29 '16 at 18:51
@Tunaki - thanks for pointing to the tutorial – Saurabh Kumar May 29 '16 at 18:54
@Tunaki : i updated the translation. Could you please check and tell me if i did it correct ? – Saurabh Kumar May 29 '16 at 18:58
No you shouldn't call `productDTOs.add` inside your `map` operation. `map` is supposed to transform one object into another. `productDTOs` will be the result of the collect call. – Tunaki May 29 '16 at 19:00

Null check inside Java 8 streams forEach

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