How to sort by two fields in Java?

Question

I have array of objects person (int age; String name;).

How can I sort this array alphabetically by name and then by age?

Which algorithm would

Answer 1

Create as many comparators as necessary. After, call the method "thenComparing" for each order category. It's a way of doing by Streams. See:

//Sort by first and last name
System.out.println("\n2.Sort list of person objects by firstName then "
                                        + "by lastName then by age");
Comparator sortByFirstName 
                            = (p, o) -> p.firstName.compareToIgnoreCase(o.firstName);
Comparator sortByLastName 
                            = (p, o) -> p.lastName.compareToIgnoreCase(o.lastName);
Comparator sortByAge 
                            = (p, o) -> Integer.compare(p.age,o.age);

//Sort by first Name then Sort by last name then sort by age
personList.stream().sorted(
    sortByFirstName
        .thenComparing(sortByLastName)
        .thenComparing(sortByAge)
     ).forEach(person->
        System.out.println(person));        

Look: Sort user defined object on multiple fields – Comparator (lambda stream)