JAVA EE: How to convert Stream of Person to Stream of String using map method of Java 8 Stream

Friday 7 July 2017

How to convert Stream of Person to Stream of String using map method of Java 8 Stream

Click here to watch in Youtube :
https://www.youtube.com/watch?v=X0GijMsrDYM&list=UUhwKlOVR041tngjerWxVccw

Person.java

public class Person
{
    private int id;
    private String name;
    private int age;

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

    public int getId()
    {
        return id;
    }

    public void setId(int id)
    {
        this.id = id;
    }

    public String getName()
    {
        return name;
    }

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

    public int getAge()
    {
        return age;
    }

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

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

}

StreamDemo.java

import java.util.Arrays;
import java.util.List;

/**
 * 
 * How to convert Stream<Person> to Stream<String> using map method of
 * Stream.
 *
 */
public class StreamDemo
{
    public static void main(String[] args)
    {

        List<Person> personList = Arrays.asList(new Person(1, "Ram", 25),
                new Person(2, "Peter", 31),
                new Person(3, "Steve", 25),
                new Person(4, "Balu", 32));
        
        
        String name = personList.stream() //convert list to stream                 
                .filter(x -> "Peter".equals(x.getName())) // we want "Peter" only
                .map(Person::getName) //convert Stream<Person> to Stream<String>
                .findAny()  // If 'findAny' then return found                                   
                .orElse(null);  // If not found, return null
        
        System.out.println(name);
    }

}