How to get an element of an object from a linkedlist using streams in Java

Consider a class ABC

class ABC{
  int id;
  String text;
  getter & setter methods..
}

A list of instances of ABC is collected in a linked list.

Linkedlist<ABC>

Now, I have an input int n. Based on the input n, I need to check list of ABC instances where I can get a match (n == d)

Based on the match, I will have to retrieve the corresponding String text from the same instance of ABC.

For example:

Linkedlist<ABC> list = new Linkedlist<>();
list.add(new ABC(1,"Eagle");
list.add(new ABC(2,"Tiger");
list.add(new ABC(3,"Rabbit");

if the input n = 3,
then I need to get the below result:
"Rabbit"

I tried to use streams as below:

list.stream().filter(p -> p.getId() == n).map(ABC:: getText);

But I want only String as an answer from the above line.

Use

• findFirst to get one ABC instance, it returns an Optional<ABC>
• orElseThrow to get the real ABC or raise an exception is no match
• getText once to get its text

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String result = list.stream().filter(p -> p.getId() == n).findFirst().orElseThrow().getText();

use findFirst() and be aware return type is an Optional instance.

 String result = list.stream()
                   .filter(p -> p.getId() == n)
                   .map(ABC::getText)
                   .findFirst()
                   .orElse(null);

You can use Stream#findFirst, with the Optional#orElse.

System.out.println(
    list.stream().filter(abc -> abc.id == n)
                 .map(abc -> abc.text)
                 .findFirst()
                 .orElse(null));

Output, where n is 3.

Rabbit