JAVA EE: How to find how many people are male in the list using Java 8 Stream

Wednesday 11 October 2017

How to find how many people are male in the list using Java 8 Stream | Streams in Java 8

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https://www.youtube.com/watch?v=Cnl7KiuZXXc&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 + "]";
    }

}

StreamCountDemo.java

import java.util.ArrayList;
import java.util.List;

public class StreamCountDemo
{
    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 count() operation simply returns total number of elements in the
         * stream.
         *
         * The following code finds how many people are male:
         */
        long totalMale = personList.stream()
                .filter(p -> p.getGender().equals(Gender.MALE)).count();
        System.out.println("Total male = " + totalMale);

    }

}