How to handle nullable lists using java 8?












12














I'm making a service call and trying to handle response.
Response might have a list of something. That list might be null.



Moreover, if list not null or not empty, then
it needs to be filtered.
In the code "entry" reference might be null if filtering gives nothing or response list is empty or null.



Currently i'm getting NPE when i try to use stream() on a null response list.
How can i handle this situation?



@Getter
public class ServiceResponse {
List<ResponseEntry> entryList;
}

@Getter
public class ResponseEntry {
String value;
}


ServiceResponse serviceResponse = service.getServiceResponse();
ResponseEntry entry = serviceResponse.getEntryList()
.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst()
.orElse(null);

if (entry == null) { ... }











share|improve this question









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  • 2




    Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
    – chrylis
    Dec 27 '18 at 6:41
















12














I'm making a service call and trying to handle response.
Response might have a list of something. That list might be null.



Moreover, if list not null or not empty, then
it needs to be filtered.
In the code "entry" reference might be null if filtering gives nothing or response list is empty or null.



Currently i'm getting NPE when i try to use stream() on a null response list.
How can i handle this situation?



@Getter
public class ServiceResponse {
List<ResponseEntry> entryList;
}

@Getter
public class ResponseEntry {
String value;
}


ServiceResponse serviceResponse = service.getServiceResponse();
ResponseEntry entry = serviceResponse.getEntryList()
.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst()
.orElse(null);

if (entry == null) { ... }











share|improve this question









New contributor




Kyle Bak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
















  • 2




    Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
    – chrylis
    Dec 27 '18 at 6:41














12












12








12


4





I'm making a service call and trying to handle response.
Response might have a list of something. That list might be null.



Moreover, if list not null or not empty, then
it needs to be filtered.
In the code "entry" reference might be null if filtering gives nothing or response list is empty or null.



Currently i'm getting NPE when i try to use stream() on a null response list.
How can i handle this situation?



@Getter
public class ServiceResponse {
List<ResponseEntry> entryList;
}

@Getter
public class ResponseEntry {
String value;
}


ServiceResponse serviceResponse = service.getServiceResponse();
ResponseEntry entry = serviceResponse.getEntryList()
.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst()
.orElse(null);

if (entry == null) { ... }











share|improve this question









New contributor




Kyle Bak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I'm making a service call and trying to handle response.
Response might have a list of something. That list might be null.



Moreover, if list not null or not empty, then
it needs to be filtered.
In the code "entry" reference might be null if filtering gives nothing or response list is empty or null.



Currently i'm getting NPE when i try to use stream() on a null response list.
How can i handle this situation?



@Getter
public class ServiceResponse {
List<ResponseEntry> entryList;
}

@Getter
public class ResponseEntry {
String value;
}


ServiceResponse serviceResponse = service.getServiceResponse();
ResponseEntry entry = serviceResponse.getEntryList()
.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst()
.orElse(null);

if (entry == null) { ... }








java java-8 java-stream optional






share|improve this question









New contributor




Kyle Bak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









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Check out our Code of Conduct.









share|improve this question




share|improve this question








edited Dec 26 '18 at 23:22









Aomine

39.7k73670




39.7k73670






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asked Dec 26 '18 at 23:09









Kyle Bak

664




664




New contributor




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New contributor





Kyle Bak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Kyle Bak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 2




    Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
    – chrylis
    Dec 27 '18 at 6:41














  • 2




    Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
    – chrylis
    Dec 27 '18 at 6:41








2




2




Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
– chrylis
Dec 27 '18 at 6:41




Why might the list be null? The preferred return for list-valued methods with no reply is emptyList().
– chrylis
Dec 27 '18 at 6:41












5 Answers
5






active

oldest

votes


















11















if list not null or not empty, then it needs to be filtered.




No need for Optional here, as it's not intended to replace simple if checks.



ResponseEntry entry = null;
List<ResponseEntry> responseEntries = serviceResponse.getEntryList();
if(responseEntries != null && !responseEntries.isEmpty()){
entry = responseEntries.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst()
.orElse(null);
}



  • reads "if responseEntries is not null and responseEntries is not empty then apply the filter operation and find the first item or else null". Very readable.


On the other hand, the optional approach:



ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
.orElseGet(() -> Collections.emptyList())
.stream()
.filter(e -> "expectedValue".equals(e.getValue()))
.findFirst();

if(!entry.isPresent()){ ... } // or entry.ifPresent(e -> ...) depending on the logic you're performing inside the block



  • unnecessarily creates objects that could be avoided and not really the intention of optional to be used as a substitute for simple "if" checks.






share|improve this answer































    8















    Stream.ofNullable (Java-9)




    Returns a sequential Stream containing a single element, if non-null,
    otherwise returns an empty Stream.




    Current Code



    ResponseEntry entry = serviceResponse.getEntryList() // List<ResponseEntry>
    .stream() // NPE here // Stream<ResponseEntry>
    .filter(e -> "expectedValue".equals(e.getValue())) // filter
    .findFirst() // Optional<ResponseEntry>
    .orElse(null); // or else null


    Updated Code



    ResponseEntry entry = Stream.ofNullable(serviceResponse.getEntryList()) // Stream<List<ResponseEntry>>
    .flatMap(List::stream) // Stream<ResponseEntry>
    .filter(e -> "expectedValue".equals(e.getValue())) // filter here
    .findFirst() // Optional<ResponseEntry>
    .orElse(null); // or else null





    Optional.stream (Java-9)




    returns a sequential Stream containing only that value, otherwise
    returns an empty Stream.




    ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
    .stream() // Stream<List<ResponseEntry>>
    .flatMap(List::stream) // Stream<ResponseEntry>
    .filter(e -> "expectedValue".equals(e.getValue())) // filter here
    .findFirst() // Optional<ResponseEntry>
    .orElse(null); // or else null





    Optional.isEmpty(Java-11)




    If a value is not present, returns true, otherwise false




    Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()) // Optional<List<ResponseEntry>>
    .orElseGet(Collections::emptyList) // or else empty List
    .stream() // Stream<ResponseEntry>
    .filter(e -> "expectedValue".equals(e.getValue())) // filter
    .findFirst(); // Optional<ResponseEntry>

    if (entry.isEmpty()) { // !entry.isPresent in java-8
    // Do your work here
    }





    share|improve this answer































      7














      In Java 9, you could use the new method Objects.requireNonNullElse(T,T):



      Objects.requireNonNullElse(serviceResponse.getEntryList(),
      Collections.emptyList())


      Apache Commons Collections actually has a method ListUtils.emptyIfNull(List<T>) which returns an empty list if the argument list is null. That's even better, but Objects.requireNonNullElse is the closest thing to it in Java SE.



      If you're restricted to just Java 8, then I agree with Aomine's answer that trying to do something like go through Optional is worse than an if statement.






      share|improve this answer





























        5














        You could simply use the ternary operator:



        ServiceResponse serviceResponse = service.getServiceResponse();
        List<ResponseEntry> list = serviceResponse.getEntryList();

        ResponseEntry entry = (list == null ? Collections.emptyList() : list)
        .stream()
        .filter(e -> "expectedValue".equals(e.getValue()))
        .findFirst()
        .orElse(null);

        if (entry == null) { ... }


        Sometimes, traditional is better IMO.






        share|improve this answer





























          1














          Another option would be to use the Optional monad:



          Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()).flatMap(list ->
          list.stream().filter(e -> "expectedValue".equals(e.getValue())).findFirst()
          );

          if (!entry.isPresent()) {

          }


          You might even use orElseGet instead of that if statement if your objective is to build (and return) a value, instead of executing a side effect.






          share|improve this answer





















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            5 Answers
            5






            active

            oldest

            votes








            5 Answers
            5






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            11















            if list not null or not empty, then it needs to be filtered.




            No need for Optional here, as it's not intended to replace simple if checks.



            ResponseEntry entry = null;
            List<ResponseEntry> responseEntries = serviceResponse.getEntryList();
            if(responseEntries != null && !responseEntries.isEmpty()){
            entry = responseEntries.stream()
            .filter(e -> "expectedValue".equals(e.getValue()))
            .findFirst()
            .orElse(null);
            }



            • reads "if responseEntries is not null and responseEntries is not empty then apply the filter operation and find the first item or else null". Very readable.


            On the other hand, the optional approach:



            ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
            .orElseGet(() -> Collections.emptyList())
            .stream()
            .filter(e -> "expectedValue".equals(e.getValue()))
            .findFirst();

            if(!entry.isPresent()){ ... } // or entry.ifPresent(e -> ...) depending on the logic you're performing inside the block



            • unnecessarily creates objects that could be avoided and not really the intention of optional to be used as a substitute for simple "if" checks.






            share|improve this answer




























              11















              if list not null or not empty, then it needs to be filtered.




              No need for Optional here, as it's not intended to replace simple if checks.



              ResponseEntry entry = null;
              List<ResponseEntry> responseEntries = serviceResponse.getEntryList();
              if(responseEntries != null && !responseEntries.isEmpty()){
              entry = responseEntries.stream()
              .filter(e -> "expectedValue".equals(e.getValue()))
              .findFirst()
              .orElse(null);
              }



              • reads "if responseEntries is not null and responseEntries is not empty then apply the filter operation and find the first item or else null". Very readable.


              On the other hand, the optional approach:



              ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
              .orElseGet(() -> Collections.emptyList())
              .stream()
              .filter(e -> "expectedValue".equals(e.getValue()))
              .findFirst();

              if(!entry.isPresent()){ ... } // or entry.ifPresent(e -> ...) depending on the logic you're performing inside the block



              • unnecessarily creates objects that could be avoided and not really the intention of optional to be used as a substitute for simple "if" checks.






              share|improve this answer


























                11












                11








                11







                if list not null or not empty, then it needs to be filtered.




                No need for Optional here, as it's not intended to replace simple if checks.



                ResponseEntry entry = null;
                List<ResponseEntry> responseEntries = serviceResponse.getEntryList();
                if(responseEntries != null && !responseEntries.isEmpty()){
                entry = responseEntries.stream()
                .filter(e -> "expectedValue".equals(e.getValue()))
                .findFirst()
                .orElse(null);
                }



                • reads "if responseEntries is not null and responseEntries is not empty then apply the filter operation and find the first item or else null". Very readable.


                On the other hand, the optional approach:



                ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                .orElseGet(() -> Collections.emptyList())
                .stream()
                .filter(e -> "expectedValue".equals(e.getValue()))
                .findFirst();

                if(!entry.isPresent()){ ... } // or entry.ifPresent(e -> ...) depending on the logic you're performing inside the block



                • unnecessarily creates objects that could be avoided and not really the intention of optional to be used as a substitute for simple "if" checks.






                share|improve this answer















                if list not null or not empty, then it needs to be filtered.




                No need for Optional here, as it's not intended to replace simple if checks.



                ResponseEntry entry = null;
                List<ResponseEntry> responseEntries = serviceResponse.getEntryList();
                if(responseEntries != null && !responseEntries.isEmpty()){
                entry = responseEntries.stream()
                .filter(e -> "expectedValue".equals(e.getValue()))
                .findFirst()
                .orElse(null);
                }



                • reads "if responseEntries is not null and responseEntries is not empty then apply the filter operation and find the first item or else null". Very readable.


                On the other hand, the optional approach:



                ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                .orElseGet(() -> Collections.emptyList())
                .stream()
                .filter(e -> "expectedValue".equals(e.getValue()))
                .findFirst();

                if(!entry.isPresent()){ ... } // or entry.ifPresent(e -> ...) depending on the logic you're performing inside the block



                • unnecessarily creates objects that could be avoided and not really the intention of optional to be used as a substitute for simple "if" checks.







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Dec 26 '18 at 23:34

























                answered Dec 26 '18 at 23:11









                Aomine

                39.7k73670




                39.7k73670

























                    8















                    Stream.ofNullable (Java-9)




                    Returns a sequential Stream containing a single element, if non-null,
                    otherwise returns an empty Stream.




                    Current Code



                    ResponseEntry entry = serviceResponse.getEntryList() // List<ResponseEntry>
                    .stream() // NPE here // Stream<ResponseEntry>
                    .filter(e -> "expectedValue".equals(e.getValue())) // filter
                    .findFirst() // Optional<ResponseEntry>
                    .orElse(null); // or else null


                    Updated Code



                    ResponseEntry entry = Stream.ofNullable(serviceResponse.getEntryList()) // Stream<List<ResponseEntry>>
                    .flatMap(List::stream) // Stream<ResponseEntry>
                    .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                    .findFirst() // Optional<ResponseEntry>
                    .orElse(null); // or else null





                    Optional.stream (Java-9)




                    returns a sequential Stream containing only that value, otherwise
                    returns an empty Stream.




                    ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                    .stream() // Stream<List<ResponseEntry>>
                    .flatMap(List::stream) // Stream<ResponseEntry>
                    .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                    .findFirst() // Optional<ResponseEntry>
                    .orElse(null); // or else null





                    Optional.isEmpty(Java-11)




                    If a value is not present, returns true, otherwise false




                    Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()) // Optional<List<ResponseEntry>>
                    .orElseGet(Collections::emptyList) // or else empty List
                    .stream() // Stream<ResponseEntry>
                    .filter(e -> "expectedValue".equals(e.getValue())) // filter
                    .findFirst(); // Optional<ResponseEntry>

                    if (entry.isEmpty()) { // !entry.isPresent in java-8
                    // Do your work here
                    }





                    share|improve this answer




























                      8















                      Stream.ofNullable (Java-9)




                      Returns a sequential Stream containing a single element, if non-null,
                      otherwise returns an empty Stream.




                      Current Code



                      ResponseEntry entry = serviceResponse.getEntryList() // List<ResponseEntry>
                      .stream() // NPE here // Stream<ResponseEntry>
                      .filter(e -> "expectedValue".equals(e.getValue())) // filter
                      .findFirst() // Optional<ResponseEntry>
                      .orElse(null); // or else null


                      Updated Code



                      ResponseEntry entry = Stream.ofNullable(serviceResponse.getEntryList()) // Stream<List<ResponseEntry>>
                      .flatMap(List::stream) // Stream<ResponseEntry>
                      .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                      .findFirst() // Optional<ResponseEntry>
                      .orElse(null); // or else null





                      Optional.stream (Java-9)




                      returns a sequential Stream containing only that value, otherwise
                      returns an empty Stream.




                      ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                      .stream() // Stream<List<ResponseEntry>>
                      .flatMap(List::stream) // Stream<ResponseEntry>
                      .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                      .findFirst() // Optional<ResponseEntry>
                      .orElse(null); // or else null





                      Optional.isEmpty(Java-11)




                      If a value is not present, returns true, otherwise false




                      Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()) // Optional<List<ResponseEntry>>
                      .orElseGet(Collections::emptyList) // or else empty List
                      .stream() // Stream<ResponseEntry>
                      .filter(e -> "expectedValue".equals(e.getValue())) // filter
                      .findFirst(); // Optional<ResponseEntry>

                      if (entry.isEmpty()) { // !entry.isPresent in java-8
                      // Do your work here
                      }





                      share|improve this answer


























                        8












                        8








                        8







                        Stream.ofNullable (Java-9)




                        Returns a sequential Stream containing a single element, if non-null,
                        otherwise returns an empty Stream.




                        Current Code



                        ResponseEntry entry = serviceResponse.getEntryList() // List<ResponseEntry>
                        .stream() // NPE here // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null


                        Updated Code



                        ResponseEntry entry = Stream.ofNullable(serviceResponse.getEntryList()) // Stream<List<ResponseEntry>>
                        .flatMap(List::stream) // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null





                        Optional.stream (Java-9)




                        returns a sequential Stream containing only that value, otherwise
                        returns an empty Stream.




                        ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                        .stream() // Stream<List<ResponseEntry>>
                        .flatMap(List::stream) // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null





                        Optional.isEmpty(Java-11)




                        If a value is not present, returns true, otherwise false




                        Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()) // Optional<List<ResponseEntry>>
                        .orElseGet(Collections::emptyList) // or else empty List
                        .stream() // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter
                        .findFirst(); // Optional<ResponseEntry>

                        if (entry.isEmpty()) { // !entry.isPresent in java-8
                        // Do your work here
                        }





                        share|improve this answer















                        Stream.ofNullable (Java-9)




                        Returns a sequential Stream containing a single element, if non-null,
                        otherwise returns an empty Stream.




                        Current Code



                        ResponseEntry entry = serviceResponse.getEntryList() // List<ResponseEntry>
                        .stream() // NPE here // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null


                        Updated Code



                        ResponseEntry entry = Stream.ofNullable(serviceResponse.getEntryList()) // Stream<List<ResponseEntry>>
                        .flatMap(List::stream) // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null





                        Optional.stream (Java-9)




                        returns a sequential Stream containing only that value, otherwise
                        returns an empty Stream.




                        ResponseEntry entry = Optional.ofNullable(serviceResponse.getEntryList())
                        .stream() // Stream<List<ResponseEntry>>
                        .flatMap(List::stream) // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter here
                        .findFirst() // Optional<ResponseEntry>
                        .orElse(null); // or else null





                        Optional.isEmpty(Java-11)




                        If a value is not present, returns true, otherwise false




                        Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()) // Optional<List<ResponseEntry>>
                        .orElseGet(Collections::emptyList) // or else empty List
                        .stream() // Stream<ResponseEntry>
                        .filter(e -> "expectedValue".equals(e.getValue())) // filter
                        .findFirst(); // Optional<ResponseEntry>

                        if (entry.isEmpty()) { // !entry.isPresent in java-8
                        // Do your work here
                        }






                        share|improve this answer














                        share|improve this answer



                        share|improve this answer








                        edited Dec 27 '18 at 1:09

























                        answered Dec 27 '18 at 0:40









                        nullpointer

                        42.2k1089175




                        42.2k1089175























                            7














                            In Java 9, you could use the new method Objects.requireNonNullElse(T,T):



                            Objects.requireNonNullElse(serviceResponse.getEntryList(),
                            Collections.emptyList())


                            Apache Commons Collections actually has a method ListUtils.emptyIfNull(List<T>) which returns an empty list if the argument list is null. That's even better, but Objects.requireNonNullElse is the closest thing to it in Java SE.



                            If you're restricted to just Java 8, then I agree with Aomine's answer that trying to do something like go through Optional is worse than an if statement.






                            share|improve this answer


























                              7














                              In Java 9, you could use the new method Objects.requireNonNullElse(T,T):



                              Objects.requireNonNullElse(serviceResponse.getEntryList(),
                              Collections.emptyList())


                              Apache Commons Collections actually has a method ListUtils.emptyIfNull(List<T>) which returns an empty list if the argument list is null. That's even better, but Objects.requireNonNullElse is the closest thing to it in Java SE.



                              If you're restricted to just Java 8, then I agree with Aomine's answer that trying to do something like go through Optional is worse than an if statement.






                              share|improve this answer
























                                7












                                7








                                7






                                In Java 9, you could use the new method Objects.requireNonNullElse(T,T):



                                Objects.requireNonNullElse(serviceResponse.getEntryList(),
                                Collections.emptyList())


                                Apache Commons Collections actually has a method ListUtils.emptyIfNull(List<T>) which returns an empty list if the argument list is null. That's even better, but Objects.requireNonNullElse is the closest thing to it in Java SE.



                                If you're restricted to just Java 8, then I agree with Aomine's answer that trying to do something like go through Optional is worse than an if statement.






                                share|improve this answer












                                In Java 9, you could use the new method Objects.requireNonNullElse(T,T):



                                Objects.requireNonNullElse(serviceResponse.getEntryList(),
                                Collections.emptyList())


                                Apache Commons Collections actually has a method ListUtils.emptyIfNull(List<T>) which returns an empty list if the argument list is null. That's even better, but Objects.requireNonNullElse is the closest thing to it in Java SE.



                                If you're restricted to just Java 8, then I agree with Aomine's answer that trying to do something like go through Optional is worse than an if statement.







                                share|improve this answer












                                share|improve this answer



                                share|improve this answer










                                answered Dec 26 '18 at 23:55









                                Radiodef

                                31.7k126596




                                31.7k126596























                                    5














                                    You could simply use the ternary operator:



                                    ServiceResponse serviceResponse = service.getServiceResponse();
                                    List<ResponseEntry> list = serviceResponse.getEntryList();

                                    ResponseEntry entry = (list == null ? Collections.emptyList() : list)
                                    .stream()
                                    .filter(e -> "expectedValue".equals(e.getValue()))
                                    .findFirst()
                                    .orElse(null);

                                    if (entry == null) { ... }


                                    Sometimes, traditional is better IMO.






                                    share|improve this answer


























                                      5














                                      You could simply use the ternary operator:



                                      ServiceResponse serviceResponse = service.getServiceResponse();
                                      List<ResponseEntry> list = serviceResponse.getEntryList();

                                      ResponseEntry entry = (list == null ? Collections.emptyList() : list)
                                      .stream()
                                      .filter(e -> "expectedValue".equals(e.getValue()))
                                      .findFirst()
                                      .orElse(null);

                                      if (entry == null) { ... }


                                      Sometimes, traditional is better IMO.






                                      share|improve this answer
























                                        5












                                        5








                                        5






                                        You could simply use the ternary operator:



                                        ServiceResponse serviceResponse = service.getServiceResponse();
                                        List<ResponseEntry> list = serviceResponse.getEntryList();

                                        ResponseEntry entry = (list == null ? Collections.emptyList() : list)
                                        .stream()
                                        .filter(e -> "expectedValue".equals(e.getValue()))
                                        .findFirst()
                                        .orElse(null);

                                        if (entry == null) { ... }


                                        Sometimes, traditional is better IMO.






                                        share|improve this answer












                                        You could simply use the ternary operator:



                                        ServiceResponse serviceResponse = service.getServiceResponse();
                                        List<ResponseEntry> list = serviceResponse.getEntryList();

                                        ResponseEntry entry = (list == null ? Collections.emptyList() : list)
                                        .stream()
                                        .filter(e -> "expectedValue".equals(e.getValue()))
                                        .findFirst()
                                        .orElse(null);

                                        if (entry == null) { ... }


                                        Sometimes, traditional is better IMO.







                                        share|improve this answer












                                        share|improve this answer



                                        share|improve this answer










                                        answered Dec 27 '18 at 1:52









                                        Federico Peralta Schaffner

                                        21.9k43370




                                        21.9k43370























                                            1














                                            Another option would be to use the Optional monad:



                                            Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()).flatMap(list ->
                                            list.stream().filter(e -> "expectedValue".equals(e.getValue())).findFirst()
                                            );

                                            if (!entry.isPresent()) {

                                            }


                                            You might even use orElseGet instead of that if statement if your objective is to build (and return) a value, instead of executing a side effect.






                                            share|improve this answer


























                                              1














                                              Another option would be to use the Optional monad:



                                              Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()).flatMap(list ->
                                              list.stream().filter(e -> "expectedValue".equals(e.getValue())).findFirst()
                                              );

                                              if (!entry.isPresent()) {

                                              }


                                              You might even use orElseGet instead of that if statement if your objective is to build (and return) a value, instead of executing a side effect.






                                              share|improve this answer
























                                                1












                                                1








                                                1






                                                Another option would be to use the Optional monad:



                                                Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()).flatMap(list ->
                                                list.stream().filter(e -> "expectedValue".equals(e.getValue())).findFirst()
                                                );

                                                if (!entry.isPresent()) {

                                                }


                                                You might even use orElseGet instead of that if statement if your objective is to build (and return) a value, instead of executing a side effect.






                                                share|improve this answer












                                                Another option would be to use the Optional monad:



                                                Optional<ResponseEntry> entry = Optional.ofNullable(serviceResponse.getEntryList()).flatMap(list ->
                                                list.stream().filter(e -> "expectedValue".equals(e.getValue())).findFirst()
                                                );

                                                if (!entry.isPresent()) {

                                                }


                                                You might even use orElseGet instead of that if statement if your objective is to build (and return) a value, instead of executing a side effect.







                                                share|improve this answer












                                                share|improve this answer



                                                share|improve this answer










                                                answered Dec 27 '18 at 13:37









                                                Bergi

                                                363k58540866




                                                363k58540866






















                                                    Kyle Bak is a new contributor. Be nice, and check out our Code of Conduct.










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                                                    Kyle Bak is a new contributor. Be nice, and check out our Code of Conduct.













                                                    Kyle Bak is a new contributor. Be nice, and check out our Code of Conduct.












                                                    Kyle Bak is a new contributor. Be nice, and check out our Code of Conduct.
















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