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

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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.

java java-stream

share|improve this question

edited 3 hours ago

risingTide

asked 5 hours ago

risingTiderisingTide

60841238

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Your original code seems succinct enough
  
  – GBlodgett
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  .map(Arrays::asList)
  
  – shmosel
  4 hours ago
  

  
  
  
  

add a comment | 

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.

java java-stream

share|improve this question

edited 3 hours ago

risingTide

asked 5 hours ago

risingTiderisingTide

60841238

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Your original code seems succinct enough
  
  – GBlodgett
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

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

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  .map(Arrays::asList)
  
  – shmosel
  4 hours ago
  

  
  
  
  

add a comment | 

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

edited 3 hours ago

risingTide

asked 5 hours ago

risingTiderisingTide

60841238

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;

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

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

share|improve this question

edited 3 hours ago

risingTide

asked 5 hours ago

risingTiderisingTide

60841238

share|improve this question

edited 3 hours ago

risingTide

asked 5 hours ago

risingTiderisingTide

60841238

asked 5 hours ago

risingTiderisingTide

60841238

asked 5 hours ago

risingTiderisingTide

60841238

2 Answers
2

active

oldest

votes

6

You might use the map :

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

share|improve this answer

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

add a comment | 

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

edited 4 hours ago

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

add a comment | 

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6

You might use the map :

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

share|improve this answer

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

add a comment | 

6

You might use the map :

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

share|improve this answer

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

add a comment | 

You might use the map :

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

share|improve this answer

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

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

share|improve this answer

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

11k1930

answered 4 hours ago

Mạnh Quyết NguyễnMạnh Quyết Nguyễn

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

edited 4 hours ago

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

add a comment | 

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

edited 4 hours ago

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

add a comment | 

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

edited 4 hours ago

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

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

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

share|improve this answer

edited 4 hours ago

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363

answered 4 hours ago

Jacob G.Jacob G.

16.3k52363