Java 8 – How to sort list with stream.sorted()
Few examples to show you how to sort a List with stream.sorted()
1. List
1.1 Sort a List with Comparator.naturalOrder()
package com.mkyong.sorted;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
public class StreamApplication {
public static void main(String[] args) {
List<String> list = Arrays.asList("9", "A", "Z", "1", "B", "Y", "4", "a", "c");
/*
List<String> sortedList = list.stream()
.sorted(Comparator.naturalOrder())
.collect(Collectors.toList());
List<String> sortedList = list.stream()
.sorted((o1,o2)-> o1.compareTo(o2))
.collect(Collectors.toList());
*/
List<String> sortedList = list.stream().sorted().collect(Collectors.toList());
sortedList.forEach(System.out::println);
}
}
Output
1
4
9
A
B
Y
Z
a
c
1.2 Sort a List with Comparator.reverseOrder()
package com.mkyong.sorted;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
public class StreamApplication {
public static void main(String[] args) {
List<String> list = Arrays.asList("9", "A", "Z", "1", "B", "Y", "4", "a", "c");
/*
List<String> sortedList = list.stream()
.sorted((o1,o2)-> o2.compareTo(o1))
.collect(Collectors.toList());
*/
List<String> sortedList = list.stream()
.sorted(Comparator.reverseOrder())
.collect(Collectors.toList());
sortedList.forEach(System.out::println);
}
}
Output
c
a
Z
Y
B
A
9
4
1
2. List Objects
1.1 Sort by age, natural order.
package com.mkyong.sorted;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
public class StreamApplication {
static List<User> users = Arrays.asList(
new User("C", 30),
new User("D", 40),
new User("A", 10),
new User("B", 20),
new User("E", 50));
public static void main(String[] args) {
/*List<User> sortedList = users.stream()
.sorted((o1, o2) -> o1.getAge() - o2.getAge())
.collect(Collectors.toList());*/
List<User> sortedList = users.stream()
.sorted(Comparator.comparingInt(User::getAge))
.collect(Collectors.toList());
sortedList.forEach(System.out::println);
}
static class User {
private String name;
private int age;
public User(String name, int age) {
this.name = name;
this.age = age;
}
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 "User{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
}
Output
User{name='A', age=10}
User{name='B', age=20}
User{name='C', age=30}
User{name='D', age=40}
User{name='E', age=50}
1.2 reverse order.
List<User> sortedList = users.stream()
.sorted(Comparator.comparingInt(User::getAge)
.reversed())
.collect(Collectors.toList());
sortedList.forEach(System.out::println);
Output
User{name='E', age=50}
User{name='D', age=40}
User{name='C', age=30}
User{name='B', age=20}
User{name='A', age=10}
1.3 Sort by name
/*List<User> sortedList = users.stream()
.sorted((o1, o2) -> o1.getName().compareTo(o2.getName()))
.collect(Collectors.toList());*/
List<User> sortedList = users.stream()
.sorted(Comparator.comparing(User::getName))
.collect(Collectors.toList());
References
About Author
Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities.
I always like your examples. All complicated issues solved by you in very simple examples.
{“ABC25”, “DEF10”, “GHI88”, “XYZ14”}
Wonderful Page! Simple and effective examples. Thanks so much!
How do I have your’s theme of code on this site, I’m interested in it so much.
Thank you a lot for your sharing.
Have a nice date!
Mind blowing mkyong…
Dears: a dummy and experimental question can be:
Why I need to do this:
Comparator.comparingInt(User::getAge)
Because I worked in apps wich got data directly order from SQL, so in what I need the data in memory in the back-end, end of the day, that would be main use of this? Since Java is a Backend Language, with a JavaScript part in the Front-End, in most of the cases.
Greetings
I have list of strings as below:
countries.add(“India”);
countries.add(“Russia”);
countries.add(“Italy”);
countries.add(“England”);
I want to create a static method named “sortCountriesByName()” and
Sort the List using Comparator(Lambda Exp). Sort in the reverse alphabetical order
Please helpme
public static void main(String[] args) {
List countries = new ArrayList();
countries.add(“India”);
countries.add(“Russia”);
countries.add(“Italy”);
countries.add(“England”);
System.out.println(sortCountriesByName(countries));
}
static List sortCountriesByName(List list){
return list.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());
}
Hi,
I have a requirement where I should able to sort list of items from child object (Its a Set).
finalSortedAndPaginatedResult.stream()
.sorted(Comparator.comparing(((Function) RuleReferenceMaster::getDpRuleRefMappings)
.andThen(DatapointRuleMappingMaster::getPriority),Comparator.nullsFirst(Comparator.naturalOrder()))
.reversed())
.collect(Collectors.toList());
Where DatapointRuleMappingMaster is a Set
Hi,
While declaring User class as static I am getting below error.
“Illegal modifier for the class User; only public, abstract & final are permitted”
Could anyone please tell me, why I am getting this. I am using jdk 8 and eclipse IDE.
Thanks in advance!
Hello ,
Thanks for this tutorial.
How to sort User using tow parameter age and name ?
List sortedList = users.stream()
.sorted(Comparator.comparingInt(User::getAge).thenComparing(Comparator.comparing(User::getName)))
.collect(Collectors.toList());
thenComparing is not working . Below is working code
List<User> sortedList = users.stream() .sorted(Comparator.comparingInt(User::getAge)).sorted(Comparator.comparing(User::getName)) .collect(Collectors.toList());Sorry Your above code is also working fine
Thanks, very concrete.