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Java list null check before Stream and return as Optional


By : rezarnmsh
Date : September 14 2020, 05:00 PM
it fixes the issue You returned List while your method signature is Optional>
Try this one:
code :
return employee != null ? Optional.of(employee.stream()
            .filter(Objects::nonNull)
            .filter(e -> e.getType != null)
            .collect(Collectors.toList())) : Optional.ofNullable(Collections.emptyList());


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Utility to check null and return size as 0 if empty for a collection/list in java


By : 123SuperC
Date : March 29 2020, 07:55 AM
I wish this help you I have list which can be null sometimes, the return type should be int ex: , What about
code :
int size = (list == null) ? 0 : list.size();

Avoiding "null-check" in List processing using Optional of Java 8


By : Anzeela Haneef
Date : March 29 2020, 07:55 AM
To fix this issue In Class Site, I have two utility methods. , Here's one way:
code :
return sites.stream()
        .map(Site::parseStub)
        .filter(Optional::isPresent)
        .map(Optional::get)
        .collect(Collectors.toList());

"Unwrap" Optional of Optional.empty before return in a Java stream (or Parallel Stream)


By : Whiker Fan
Date : March 29 2020, 07:55 AM
this one helps. You could use Optional#flatMap to 'unwrap' the inner optional:
code :
public boolean hasFirst() {
   return types.parallelStream()
       .filter(it -> it.getTotalAmount() > 0)
       .map(TypeA::getFirst)
       .findFirst() // return Optional[Optional.empty]
       .flatMap(i -> i) // <---
       .isPresent(); // true
}

Java Stream API: Optional if not null proceed


By : 杨金枭
Date : March 29 2020, 07:55 AM
around this issue Note that Optional can't contain null values, so your code will either execute the conditional, or fail with an exception at get().
You could change the get() to orElse(null); but you'd still need the separate conditional.
code :
String name = 
    array.stream()
        .min(myComparator)
        .map(m -> m.getData().get("name"))
        .orElse(someDefaultValue);

Use java.util.Optional to return null for subfield of Optional type


By : Rahul sharma
Date : March 29 2020, 07:55 AM
it should still fix some issue Use map(Function mapper)
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