Thursday, 12 October 2017

How to find the youngest female person using min method of Java 8 Stream | Streams in Java 8


Click here to watch in Youtube : 
https://www.youtube.com/watch?v=g7G380lDv0c&list=UUhwKlOVR041tngjerWxVccw

Person.java
enum Gender
{
    MALE, FEMALE
}

public class Person
{
    private String name;
    private String email;
    private Gender gender;
    private int age;

    public Person(String name, String email, Gender gender, int age)
    {
        super();
        this.name = name;
        this.email = email;
        this.gender = gender;
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public String getEmail()
    {
        return email;
    }

    public void setEmail(String email)
    {
        this.email = email;
    }

    public Gender getGender()
    {
        return gender;
    }

    public void setGender(Gender gender)
    {
        this.gender = gender;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    @Override
    public String toString()
    {
        return "Person [name=" + name + "]";
    }

}
StreamMinDemo.java
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

public class StreamMinDemo
{
    public static void main(String[] args)
    {
        List<Person> personList = new ArrayList<>();

        personList.add(new Person("Alice","alice@gmail.com",    Gender.FEMALE, 26));
        personList.add(new Person("Bob","bob@gmail.com", Gender.MALE, 32));
        personList.add(new Person("Carol","carol@gmail.com",Gender.FEMALE, 23));
        personList.add(new Person("David","david@gmail.com",    Gender.MALE, 39));
        personList.add(new Person("Eric","eric@gmail.com", Gender.MALE, 26));
        
        /*
         * The min(comparator) is a special reduction operation that returns the
         * minimum element in the stream according to the provided comparator.
         * It returns an Optional which is a container object that contains the
         * value. 
         * 
         * For example, the following code snippet finds the youngest
         * female person in the list:
         */
        Optional<Person> optional = personList.stream()
                .filter(p -> p.getGender().equals(Gender.FEMALE))
                .min((p1, p2) -> p1.getAge() - p2.getAge());
        
        if (optional.isPresent())
        {
            Person youngestGirl = optional.get();
            System.out.println("The youngest girl is: " + youngestGirl.getName()
                    + " (" + youngestGirl.getAge() + ")");
        }
        
    }

}
Output
The youngest girl is: Carol (23)

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/StreamDemo_min_youngestgirl.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/StreamDemo_min_youngestgirl

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/17906082b9d83230789adc7b5df551c73ce2b46f/BasicJava/StreamDemo_min_youngestgirl/?at=master

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