Java 8 Stream Sorting Multiple Fields Examples

Example to sort the stream on multiple fields using Comparaor.comparing() and Comparator.thenComparing() methods in java 8.

The below program is to sort the Employee list on name and age properties.

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class SortMultipleFieldsSorted {

    public static void main(String[] args) {


        Employee e1 = new Employee(111, "Hari", 30);
        Employee e2 = new Employee(222, "Jool", 35);
        Employee e3 = new Employee(333, "Hari", 28);
        Employee e4 = new Employee(444, "Jool", 23);

        List<Employee> unsortredList = Arrays.asList(e1, e2, e3, e4);

        Comparator<Employee> idEmployeeComparator = Comparator.comparing(Employee::getName);

        Comparator<Employee> titleEmployeeComparator = Comparator.comparing(Employee::getAge);

        Comparator<Employee> multipleFieldsComparator = idEmployeeComparator.thenComparing(titleEmployeeComparator);

        System.out.println("Unsorted Emp List : ");

        for (Employee e : unsortredList) {
            System.out.println(e);
        }

        List<Employee> sortedList1 = unsortredList.stream().sorted(multipleFieldsComparator).collect(Collectors.toList());

        System.out.println("After sorting books list : ");


        for (Employee e : sortedList1) {
            System.out.println(e);
        }


        List<Employee> unsortredEmpList2 = Arrays.asList(e1, e2, e3, e4);

        System.out.println("Unsorted Books List 2 : ");
        for (Employee e : unsortredEmpList2) {
            System.out.println(e);
        }

        List<Employee> sortedList2 = unsortredEmpList2.stream().sorted(multipleFieldsComparator).collect(Collectors.toList());

        System.out.println("After sorting emp list 2: ");


        for (Employee e : sortedList2) {
            System.out.println(e);
        }
    }
}

class Employee {

    private int id;
    private String name;
    private int age;

    public Employee(int id, String name, int age) {
        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 "Employee{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

Output:

Unsorted Emp List : 
Employee{id=111, name='Hari', age=30}
Employee{id=222, name='Jool', age=35}
Employee{id=333, name='Hari', age=28}
Employee{id=444, name='Jool', age=23}
After sorting books list : 
Employee{id=333, name='Hari', age=28}
Employee{id=111, name='Hari', age=30}
Employee{id=444, name='Jool', age=23}
Employee{id=222, name='Jool', age=35}
Unsorted Books List 2 : 
Employee{id=111, name='Hari', age=30}
Employee{id=222, name='Jool', age=35}
Employee{id=333, name='Hari', age=28}
Employee{id=444, name='Jool', age=23}
After sorting emp list 2: 
Employee{id=333, name='Hari', age=28}
Employee{id=111, name='Hari', age=30}
Employee{id=444, name='Jool', age=23}
Employee{id=222, name='Jool', age=35}

Comparaor.comparing()