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Java 8 - find element in List

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Created by:
Tehya-Blanchard
304

In this article, we would like to show you how to find an element in List in Java 8.

In this approach we're gonna:

  • invoke stream() on the list,
  • call collect() method with Collector.toList()¬†that collects all Stream elements into a List instance.

Practical example

In this example, we use Java 8 Stream API to find the first occurrence of User named Tom in the List.

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Example {

    public static void main(String[] args) throws IOException {

        // Create list of users --------------------
        List<User> users = new ArrayList<>(Arrays.asList(
                new User("Tom", 20),
                new User("Kate", 21),
                new User("Ann", 22)
        ));

        // find an element in List --------------------

        List<User> foundUsers = users.stream()
                .filter(user -> "Tom".equals(user.getName()))
                .collect(Collectors.toList());

        System.out.println(foundUsers);
    }
}

Output:

User{ name='Tom', age=20 }

Note:

We create new list - foundUsers to collect the result in case there are many users named Tom.

Note:

In the section below you can find the implementation of the User class

User class

User.java:

public class User {
    private final String name;
    private final int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "User{ " +
                "name='" + name + '\'' +
                ", age=" + age +
                " }";
    }
}
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