Clash Royale CLAN TAG#URR8PPP

Split string in a stream Java

I have a POJO class Product

List<Product> list = new ArrayList<>();
list.add(new Product(1, "HP Laptop Speakers", 25000));
list.add(new Product(30, "Acer Keyboard", 300));
list.add(new Product(2, "Dell Mouse", 150));


Now I want to split the list to get output as HP-Laptop-Speakers&&Acer-Keyboard&&Dell-Mouse.

HP-Laptop-Speakers&&Acer-Keyboard&&Dell-Mouse.

I just want a single liner in stream.
So far I have managed to get

Optional<String> temp = list.stream().
map(x -> x.name).
map(x -> x.split(" ")[0]).
reduce((str1, str2) -> str1 + "&&" + str2);
System.out.println(temp.get());


Output: HP&&Acer&&Dell

HP&&Acer&&Dell

Can someone help me out.
Thanks in advance.

6 Answers
6

First, the split() operation is not necessary. While you could split all the pieces and then join them together like that, it is far simpler to use a replace or replaceAll call instead.

split()

replace

replaceAll

Secondly, the reduce operation will not be very efficient since it is creating lots of intermediary Strings and StringBuilders. Instead, you should use the String joining Collector, which is more efficient:

String

StringBuilder

String

String temp = list.stream()
.map(x -> x.name.replace(" ", "-"))
.collect(Collectors.joining("&&"));


The second map operation you write keep the first word.

map

Instead, here what you can do :

Replace the spaces (\s as regex) by a -

\s

-

Optional<String> temp = list.stream()
.map(x -> x.name)
.map(x -> x.replaceAll("\s", "-"))
.reduce((str1, str2) -> str1 + "&&" + str2);


Split on space, and then join with the -

-

Optional<String> temp = list.stream()
.map(x -> x.name)
.map(x -> String.join("-", x.split("\s")))
.reduce((str1, str2) -> str1 + "&&" + str2);


Try to use collector on stream of strings:

.collect(Collectors.joining("&&"))


One easy way to do this would be to override the toString() method in the Product class to print the name as you want it formatted and then iterate through the list concatenating each result onto a longer string.

Optional<String> temp = list.stream().map(x -> x.name)
.map(x -> x.replaceAll("\s", "-"))
.reduce((str1, str2) -> str1 + "&&" + str2);


you need to replace this portion map(x -> x.split(" ")) with map(x -> x.replaceAll("\s","-"))

map(x -> x.split(" "))

map(x -> x.replaceAll("\s","-"))

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