update following Java 9's release

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edit approved Aug 23, 2023 at 19:35

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Java 8Stream API - Best way to transform a list: map or foreachforEach?

I have a list, myListToParse, where I want to filter the elements and apply a method on each element, and add the result in another list, myFinalList.

With the Stream API (added in Java 8), I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myFinalList = new ArrayList<>();
myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I'm open for any suggestion about a third way.

Java 8 - Best way to transform a list: map or foreach?

I have a list myListToParse where I want to filter the elements and apply a method on each element, and add the result in another list myFinalList.

With Java 8 I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myFinalList = new ArrayList<>();
myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

Java Stream API - Best way to transform a list: map or forEach?

I have a list, myListToParse, where I want to filter the elements and apply a method on each element, and add the result in another list, myFinalList.

With the Stream API (added in Java 8), I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

Method 1:

myFinalList = new ArrayList<>();
myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I'm open for any suggestion about a third way.

Notice removed Reward existing answer by Naman

occurred May 16, 2021 at 12:05

Bounty Ended with herman's answer chosen by Naman

occurred May 16, 2021 at 12:05

Notice added Reward existing answer by Naman

occurred May 13, 2021 at 2:17

Bounty Started worth 250 reputation by Naman

occurred May 13, 2021 at 2:17

added instance creation for method 1 to not give the wrong impression that it is shorter

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edited Mar 6, 2018 at 16:16

herman

12.1k
5
49
60

I have a list myListToParse where I want to filter the elements and apply a method on each element, and add the result in another list myFinalList.

With Java 8 I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myFinalList = new ArrayList<>();
myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I have a list myListToParse where I want to filter the elements and apply a method on each element, and add the result in another list myFinalList.

With Java 8 I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I have a list myListToParse where I want to filter the elements and apply a method on each element, and add the result in another list myFinalList.

With Java 8 I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myFinalList = new ArrayList<>();
myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

deleted 9 characters in body; edited tags

Source Link

edited Jan 19, 2017 at 10:50

Eran

392.1k
56
713
780

I have a first list : myListToParse where iI want to filter the elements and apply a method on each elementselement, and add the result in another list : myFinalList.

With Java 8 I noticed that I can do it in 2 different way,ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I have a first list : myListToParse where i want to filter the elements and apply a method on each elements and add the result in another list : myFinalList

With Java 8 I noticed that I can do it in 2 different way, I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

I have a list myListToParse where I want to filter the elements and apply a method on each element, and add the result in another list myFinalList.

With Java 8 I noticed that I can do it in 2 different ways. I would like to know the more efficient way between them and understand why one way is better than the other one.

I'm open for any suggestion about a third way.

Method 1:

myListToParse.stream()
        .filter(elt -> elt != null)
        .forEach(elt -> myFinalList.add(doSomething(elt)));

Method 2:

myFinalList = myListToParse.stream()
        .filter(elt -> elt != null)
        .map(elt -> doSomething(elt))
        .collect(Collectors.toList());

changed title: 'parse' is not really the correct term in this context

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edit approved Feb 4, 2015 at 11:51

herman

12.1k
5
49
60

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deleted 5 characters in body

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edited Feb 4, 2015 at 11:05

Emilien Brigand

10.6k
9
34
37

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code format, added java8 tag

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edited Feb 4, 2015 at 10:49

tobias_k

82.5k
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184

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Source Link

asked Feb 4, 2015 at 10:30

Emilien Brigand

10.6k
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34
37

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Java 8Stream API - Best way to transform a list: map or foreachforEach?

Java 8 - Best way to transform a list: map or foreach?

Java Stream API - Best way to transform a list: map or forEach?