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Using streams for a null-safe conversion from an array to list


Converting Array to ListCreate ArrayList from arrayHow to simplify a null-safe compareTo() implementation?Converting array to list in JavaConvert list to array in JavaRetrieving a List from a java.util.stream.Stream in Java 8How to Convert a Java 8 Stream to an Array?Java 8 Stream and operation on arraysHow can I create a stream from an array?How to sum a list of integers with java streams?Java 8 stream - how to properly make NPE-safe stream













8















I'm looking for a succinct way to rewrite a piece of Java code so that it uses streams to convert an array to a list in a null-safe fashion. Here's the original code:



public MailObject toMailObject(final String[] ccAddresses) 
final MailObject mailObject = new MailObject();

// line of code to be altered
mailObject.setCcAddresses(ccAddresses == null
? Collections.emptyList() : Arrays.asList(ccAddresses));

// other necessary code

return mailObject;



I've thought of doing something like this:



// psuedocode that obviously doesn't compile
Optional.ofNullable(ccAddresses).SOMETHING.orElse(Collections.emptyList());


where SOMETHING would be along the lines of:



Arrays.stream(ints).collect(Collectors.toList());


but I can't seem to get the syntax quite right.



This question was helpful but didn't exactly address my issue. Could anyone point me in the right direction? I feel like I'm close...



Thank you very much for your time.










share|improve this question



















  • 3





    Your original code seems succinct enough

    – GBlodgett
    5 hours ago











  • Fair enough, but I'm curious as to the best way it can be done using streams.

    – risingTide
    5 hours ago






  • 1





    .map(Arrays::asList)

    – shmosel
    4 hours ago















8















I'm looking for a succinct way to rewrite a piece of Java code so that it uses streams to convert an array to a list in a null-safe fashion. Here's the original code:



public MailObject toMailObject(final String[] ccAddresses) 
final MailObject mailObject = new MailObject();

// line of code to be altered
mailObject.setCcAddresses(ccAddresses == null
? Collections.emptyList() : Arrays.asList(ccAddresses));

// other necessary code

return mailObject;



I've thought of doing something like this:



// psuedocode that obviously doesn't compile
Optional.ofNullable(ccAddresses).SOMETHING.orElse(Collections.emptyList());


where SOMETHING would be along the lines of:



Arrays.stream(ints).collect(Collectors.toList());


but I can't seem to get the syntax quite right.



This question was helpful but didn't exactly address my issue. Could anyone point me in the right direction? I feel like I'm close...



Thank you very much for your time.










share|improve this question



















  • 3





    Your original code seems succinct enough

    – GBlodgett
    5 hours ago











  • Fair enough, but I'm curious as to the best way it can be done using streams.

    – risingTide
    5 hours ago






  • 1





    .map(Arrays::asList)

    – shmosel
    4 hours ago













8












8








8


1






I'm looking for a succinct way to rewrite a piece of Java code so that it uses streams to convert an array to a list in a null-safe fashion. Here's the original code:



public MailObject toMailObject(final String[] ccAddresses) 
final MailObject mailObject = new MailObject();

// line of code to be altered
mailObject.setCcAddresses(ccAddresses == null
? Collections.emptyList() : Arrays.asList(ccAddresses));

// other necessary code

return mailObject;



I've thought of doing something like this:



// psuedocode that obviously doesn't compile
Optional.ofNullable(ccAddresses).SOMETHING.orElse(Collections.emptyList());


where SOMETHING would be along the lines of:



Arrays.stream(ints).collect(Collectors.toList());


but I can't seem to get the syntax quite right.



This question was helpful but didn't exactly address my issue. Could anyone point me in the right direction? I feel like I'm close...



Thank you very much for your time.










share|improve this question
















I'm looking for a succinct way to rewrite a piece of Java code so that it uses streams to convert an array to a list in a null-safe fashion. Here's the original code:



public MailObject toMailObject(final String[] ccAddresses) 
final MailObject mailObject = new MailObject();

// line of code to be altered
mailObject.setCcAddresses(ccAddresses == null
? Collections.emptyList() : Arrays.asList(ccAddresses));

// other necessary code

return mailObject;



I've thought of doing something like this:



// psuedocode that obviously doesn't compile
Optional.ofNullable(ccAddresses).SOMETHING.orElse(Collections.emptyList());


where SOMETHING would be along the lines of:



Arrays.stream(ints).collect(Collectors.toList());


but I can't seem to get the syntax quite right.



This question was helpful but didn't exactly address my issue. Could anyone point me in the right direction? I feel like I'm close...



Thank you very much for your time.







java java-stream






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 3 hours ago







risingTide

















asked 5 hours ago









risingTiderisingTide

60841238




60841238







  • 3





    Your original code seems succinct enough

    – GBlodgett
    5 hours ago











  • Fair enough, but I'm curious as to the best way it can be done using streams.

    – risingTide
    5 hours ago






  • 1





    .map(Arrays::asList)

    – shmosel
    4 hours ago












  • 3





    Your original code seems succinct enough

    – GBlodgett
    5 hours ago











  • Fair enough, but I'm curious as to the best way it can be done using streams.

    – risingTide
    5 hours ago






  • 1





    .map(Arrays::asList)

    – shmosel
    4 hours ago







3




3





Your original code seems succinct enough

– GBlodgett
5 hours ago





Your original code seems succinct enough

– GBlodgett
5 hours ago













Fair enough, but I'm curious as to the best way it can be done using streams.

– risingTide
5 hours ago





Fair enough, but I'm curious as to the best way it can be done using streams.

– risingTide
5 hours ago




1




1





.map(Arrays::asList)

– shmosel
4 hours ago





.map(Arrays::asList)

– shmosel
4 hours ago












2 Answers
2






active

oldest

votes


















7














You might use the map :



List<String> ccAddrs = Optional.ofNullable(ccAddress)
.map(Arrays::asList)
.orElse(Collections.emptyList())





share|improve this answer






























    4














    In my opinion, the code that you have so far is perfectly readable. I think using a Stream for something like this will just complicate things. If you still want to use a Stream, then something like the following would work:



    mailObject.setCcAddresses(Stream.ofNullable(ccAddresses)
    .flatMap(Arrays::stream)
    .collect(Collectors.toUnmodifiableList()));


    As you can see, this is a more unreadable, and I wouldn't recommend it over your simple ternary expression.




    Your Optional solution is slightly more readable and would look like the following:



    mailObject.setCcAddresses(Optional.ofNullable(ccAddresses)
    .map(Arrays::asList)
    .orElse(Collections.emptyList()));





    share|improve this answer
























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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      7














      You might use the map :



      List<String> ccAddrs = Optional.ofNullable(ccAddress)
      .map(Arrays::asList)
      .orElse(Collections.emptyList())





      share|improve this answer



























        7














        You might use the map :



        List<String> ccAddrs = Optional.ofNullable(ccAddress)
        .map(Arrays::asList)
        .orElse(Collections.emptyList())





        share|improve this answer

























          7












          7








          7







          You might use the map :



          List<String> ccAddrs = Optional.ofNullable(ccAddress)
          .map(Arrays::asList)
          .orElse(Collections.emptyList())





          share|improve this answer













          You might use the map :



          List<String> ccAddrs = Optional.ofNullable(ccAddress)
          .map(Arrays::asList)
          .orElse(Collections.emptyList())






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 4 hours ago









          Mạnh Quyết NguyễnMạnh Quyết Nguyễn

          11k1930




          11k1930























              4














              In my opinion, the code that you have so far is perfectly readable. I think using a Stream for something like this will just complicate things. If you still want to use a Stream, then something like the following would work:



              mailObject.setCcAddresses(Stream.ofNullable(ccAddresses)
              .flatMap(Arrays::stream)
              .collect(Collectors.toUnmodifiableList()));


              As you can see, this is a more unreadable, and I wouldn't recommend it over your simple ternary expression.




              Your Optional solution is slightly more readable and would look like the following:



              mailObject.setCcAddresses(Optional.ofNullable(ccAddresses)
              .map(Arrays::asList)
              .orElse(Collections.emptyList()));





              share|improve this answer





























                4














                In my opinion, the code that you have so far is perfectly readable. I think using a Stream for something like this will just complicate things. If you still want to use a Stream, then something like the following would work:



                mailObject.setCcAddresses(Stream.ofNullable(ccAddresses)
                .flatMap(Arrays::stream)
                .collect(Collectors.toUnmodifiableList()));


                As you can see, this is a more unreadable, and I wouldn't recommend it over your simple ternary expression.




                Your Optional solution is slightly more readable and would look like the following:



                mailObject.setCcAddresses(Optional.ofNullable(ccAddresses)
                .map(Arrays::asList)
                .orElse(Collections.emptyList()));





                share|improve this answer



























                  4












                  4








                  4







                  In my opinion, the code that you have so far is perfectly readable. I think using a Stream for something like this will just complicate things. If you still want to use a Stream, then something like the following would work:



                  mailObject.setCcAddresses(Stream.ofNullable(ccAddresses)
                  .flatMap(Arrays::stream)
                  .collect(Collectors.toUnmodifiableList()));


                  As you can see, this is a more unreadable, and I wouldn't recommend it over your simple ternary expression.




                  Your Optional solution is slightly more readable and would look like the following:



                  mailObject.setCcAddresses(Optional.ofNullable(ccAddresses)
                  .map(Arrays::asList)
                  .orElse(Collections.emptyList()));





                  share|improve this answer















                  In my opinion, the code that you have so far is perfectly readable. I think using a Stream for something like this will just complicate things. If you still want to use a Stream, then something like the following would work:



                  mailObject.setCcAddresses(Stream.ofNullable(ccAddresses)
                  .flatMap(Arrays::stream)
                  .collect(Collectors.toUnmodifiableList()));


                  As you can see, this is a more unreadable, and I wouldn't recommend it over your simple ternary expression.




                  Your Optional solution is slightly more readable and would look like the following:



                  mailObject.setCcAddresses(Optional.ofNullable(ccAddresses)
                  .map(Arrays::asList)
                  .orElse(Collections.emptyList()));






                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited 4 hours ago

























                  answered 4 hours ago









                  Jacob G.Jacob G.

                  16.3k52363




                  16.3k52363



























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                      ValueError: Expected n_neighbors <= n_samples, but n_samples = 1, n_neighbors = 6 (SMOTE) The 2019 Stack Overflow Developer Survey Results Are InCan SMOTE be applied over sequence of words (sentences)?ValueError when doing validation with random forestsSMOTE and multi class oversamplingLogic behind SMOTE-NC?ValueError: Error when checking target: expected dense_1 to have shape (7,) but got array with shape (1,)SmoteBoost: Should SMOTE be ran individually for each iteration/tree in the boosting?solving multi-class imbalance classification using smote and OSSUsing SMOTE for Synthetic Data generation to improve performance on unbalanced dataproblem of entry format for a simple model in KerasSVM SMOTE fit_resample() function runs forever with no result