Java Comparable

Comparable: It is used to define the natural ordering of the objects within the class.--->method..compareTo()

Comparator:(TBD) It is used to define custom sorting logic externally.method..compare()

package collections;

public class mobile implements Comparable<Object> {
    String brand;
    int price;
    int ram;
    double weigth;

    mobile(String brand, int price, int ram, double weigth) {
        this.brand = brand;
        this.price = price;
        this.ram = ram;
        this.weigth = weigth;
    }

    public String toString() {
        return this.brand + " " + this.price + " " + this.ram + " " + this.weigth;

    }

    public int compareTo(Object o) // call compareTo as m1 and passes parameters as m2
    {
        // System.out.println("First "+ this.price);//m1(print and see how compare happen)
        mobile m = (mobile) o;// converting mobile class object
        // System.out.println("second "+ m.price);//m2(print and see how compare happen)
        if (this.price > m.price) {
            return 1;// ascending
        } else if (this.price < m.price) {
            return -1;// decending
        }
        return 0;//equal
    }

}

package collections;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;

public class mobshop {

    public static void main(String[] args) {
        mobile m1 = new mobile("samsang", 15000, 12, 5.0);
        mobile m2 = new mobile("vivo", 10000, 6, 7.0);
        mobile m3 = new mobile("apple", 100000, 4, 5.0);
        ArrayList al = new ArrayList();
        al.add(m1);
        al.add(m2);
        al.add(m3);

                System.out.println("Before Sorting: " + al);
        Collections.sort(al);// use to sort in order
        System.out.println("After Sorting: " + al);

        int max_price = 0;
        String brand = " ";
        Iterator it = al.iterator();
        while (it.hasNext()) {
            mobile mob = (mobile) it.next();
            if (mob.price > max_price) {
                max_price = mob.price;
                brand = mob.brand;
            }
        }
        System.out.println(max_price + " brand = " + brand);

    }

}

Output:
Before Sorting: [samsang 15000 12 5.0, vivo 10000 6 7.0, apple 100000 4 5.0]
After Sorting: [vivo 10000 6 7.0, samsang 15000 12 5.0, apple 100000 4 5.0]
100000 brand = apple

Reference:https://www.geeksforgeeks.org/comparable-vs-comparator-in-java/