Learn Java 8 streams with an example - How to sort a list

 Example 1: Sort the List In the natural order

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

public class DriverClass {
    public static void main(String[] args) {
       List<String> list = Arrays.asList("H", "A", "Z", "L", "B", "Y", "M", "a", "c");
       list.stream().sorted().collect(Collectors.toList()).forEach
                                    (System.out::println);
    }
}
Output:

A
B
H
L
M
Y
Z
a
c



Example 2: Sort the List In the reverse Order

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

public class DriverClass {

    public static void main(String[] args) {
       List<String> list = Arrays.asList("H", "A", "Z", "L", "B", "Y", "M", "a", "c");
       list.stream().sorted(Comparator.reverseOrder()).
                  collect(Collectors.toList()).forEach(System.out::println);
    }
}
Output:

c
a
Z
Y
M
L
H
B
A



Example 3: Sort the List Objects In the natural order (sort by salary)

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

public class DriverClass {
    static List<Employee> employees = Arrays.asList(
            new Employee("Alpha", 3000),
            new Employee("Beta", 40000),
            new Employee("Noob", 10000),
            new Employee("Pro", 200000),
            new Employee("Sibin", 5000));

    public static void main(String[] args) {
        List<Employee> sortedList = employees.stream()
                .sorted(Comparator.comparingInt(Employee::getSalary))
                .collect(Collectors.toList());
        sortedList.forEach(System.out::println);
    }

    static class Employee {
        private String name;
        private int salary;

        public Employee(String name, int salary) {
            this.name = name;
            this.salary = salary;
        }

        public String getName() {
            return name;
        }

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

        public int getSalary() {
            return salary;
        }

        public void setSalary(int salary) {
            this.salary = salary;
        }

        @Override
        public String toString() {
            return "Employee{" +
                    "name='" + name + '\'' +
                    ", salary=" + salary +
                    '}';
        }
    }
}
Output:

Employee{name='Alpha', salary=3000}
Employee{name='Sibin', salary=5000}
Employee{name='Noob', salary=10000}
Employee{name='Beta', salary=40000}
Employee{name='Pro', salary=200000}


Example 4: Sort the List Objects In the natural order (sort by name)

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

public class DriverClass {
    static List<Employee> employees = Arrays.asList(
            new Employee("Beta", 3000),
            new Employee("Alpha", 40000),
            new Employee("Pro", 10000),
            new Employee("Noob", 200000),
            new Employee("Sibin", 5000));

    public static void main(String[] args) {
        List<Employee> sortedList = employees.stream()
                .sorted(Comparator.comparing(Employee::getName))
                .collect(Collectors.toList());
        sortedList.forEach(System.out::println);
    }

    static class Employee {
        private String name;
        private int salary;

        public Employee(String name, int salary) {
            this.name = name;
            this.salary = salary;
        }

        public String getName() {
            return name;
        }

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

        public int getSalary() {
            return salary;
        }

        public void setSalary(int salary) {
            this.salary = salary;
        }

        @Override
        public String toString() {
            return "Employee{" +
                    "name='" + name + '\'' +
                    ", salary=" + salary +
                    '}';
        }
    }
}
Output:

Employee{name='Alpha', salary=40000}
Employee{name='Beta', salary=3000}
Employee{name='Noob', salary=200000}
Employee{name='Pro', salary=10000}
Employee{name='Sibin', salary=5000}


Example 5: Sort the List Objects In the reverse order (sort by salary)

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

public class DriverClass {
    static List<Employee> employees = Arrays.asList(
            new Employee("Beta", 3000),
            new Employee("Alpha", 40000),
            new Employee("Pro", 10000),
            new Employee("Noob", 200000),
            new Employee("Sibin", 5000));

    public static void main(String[] args) {
        List<Employee> sortedList = employees.stream()
                .sorted(Comparator.comparingInt(Employee::getSalary)
                        .reversed())
                .collect(Collectors.toList());
        sortedList.forEach(System.out::println);
    }

    static class Employee {
        private String name;
        private int salary;

        public Employee(String name, int salary) {
            this.name = name;
            this.salary = salary;
        }

        public String getName() {
            return name;
        }

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

        public int getSalary() {
            return salary;
        }

        public void setSalary(int salary) {
            this.salary = salary;
        }

        @Override
        public String toString() {
            return "Employee{" +
                    "name='" + name + '\'' +
                    ", salary=" + salary +
                    '}';
        }
    }
}
Output:

Employee{name='Noob', salary=200000}
Employee{name='Alpha', salary=40000}
Employee{name='Pro', salary=10000}
Employee{name='Sibin', salary=5000}
Employee{name='Beta', salary=3000}


Example 6: Sort the List Objects In the reverse order (sort by name)

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

public class DriverClass {
    static List<Employee> employees = Arrays.asList(
            new Employee("Beta", 3000),
            new Employee("Alpha", 40000),
            new Employee("Pro", 10000),
            new Employee("Noob", 200000),
            new Employee("Sibin", 5000));

    public static void main(String[] args) {
        List<Employee> sortedList = employees.stream()
                .sorted(Comparator.comparing(Employee::getName)
                        .reversed())
                .collect(Collectors.toList());
        sortedList.forEach(System.out::println);
    }

    static class Employee {
        private String name;
        private int salary;

        public Employee(String name, int salary) {
            this.name = name;
            this.salary = salary;
        }

        public String getName() {
            return name;
        }

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

        public int getSalary() {
            return salary;
        }

        public void setSalary(int salary) {
            this.salary = salary;
        }

        @Override
        public String toString() {
            return "Employee{" +
                    "name='" + name + '\'' +
                    ", salary=" + salary +
                    '}';
        }
    }
}
Output:

Employee{name='Sibin', salary=5000}
Employee{name='Pro', salary=10000}
Employee{name='Noob', salary=200000}
Employee{name='Beta', salary=3000}
Employee{name='Alpha', salary=40000}


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