Mastering Java's Built-in Sorting Functions: Arrays and Comparators

Hello, and welcome back! Our journey today takes us into the sorting universe in Java. We will learn about and use Java's built-in Arrays.sort() function. Additionally, we will explore how Java's Comparator interface allows us to define custom sorting rules for more complex sorting scenarios.

These ready-to-use tools in Java simplify the task of sorting significantly. Let's get started!

Sorting refers to arranging data in a specific order, which enhances the efficiency of search or merge operations on data. In real life, we sort books alphabetically or clothes by size. Similar concepts are applicable in programming, where sorting large lists of data for more effective analysis is a frequent practice.

Java offers a built-in sorting method, Arrays.sort(), to sort arrays. Here's a demonstration of how we use this method:

Sorting with Arrays.sort() makes sorting arrays of primitives a breeze. Let's see it in action!

Sorting Arrays of Primitives

int[] arr = {4, 1, 3, 2};
Arrays.sort(arr);
System.out.println(Arrays.toString(arr)); // Output: [1, 2, 3, 4]

Sorting Arrays of Objects

String[] inventory = {"Bananas", "Pears", "Apples", "Dates"};
Arrays.sort(inventory);
System.out.println(Arrays.toString(inventory));
// Output: [Apples, Bananas, Dates, Pears]

As you can see, sorting in Java is as simple as that!

Java's Comparator interface enables us to dictate the sorting order by setting custom rules. Let's sort a list of students by their grades, with alphabetical sorting applied in the event of ties in grades. Firstly, we define the Student class:

class Student {
    String name;
    int grade;

    Student(String name, int grade) {
        this.name = name;
        this.grade = grade;
    }

    public int getGrade() {return this.grade;}
    public String getName() {return this.name;}
    public String toString() {
        return name + ":" + grade;
    }
}

Note that it has to have getters for its fields for the Comparator to work.