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Let say there is a Customer class. We add objects of Customer class to an ArrayList. How can we sort the Customer objects in ArrayList by using customer firstName attribute of Customer class?

Pragya Keshap answered on February 4, 2023 Popularity 1/10 Helpfulness 1/10

answer Let say there is a Customer class. We add objects of Customer class to an ArrayList. How can we sort the Customer objects in ArrayList by using customer firstName attribute of Customer class?

Let say there is a Customer class. We add objects of Customer class to an ArrayList. How can we sort the Customer objects in ArrayList by using customer firstName attribute of Customer class?

Comment

There are two ways to handle this scenario. We can use these

options:

Comparable: Implement the Comparable interface for Customer

class and compare customer objects by firstName attribute.

Comparator: Implement Comparator for comparing two Customer

objects on the basis of firstName attribute. Then use this comparator

object in sort method of Collections class.

    // Usage of comparator
    public static Comparator<Student> StuNameComparator = new Comparator<Student>() {
 
        // Comparing attributes of students
        public int compare(Student s1, Student s2) {
            String StudentName1
                = s1.getStudentname().toUpperCase();
            String StudentName2
                = s2.getStudentname().toUpperCase();
 
            // Returning in ascending order
            return StudentName1.compareTo(
                       StudentName2);
 
            // descending order
            // return
            // StudentName2.compareTo(StudentName1);
        }
    };
 
    // Comparator for sorting the list by roll no
    public static Comparator<Student> StuRollno = new Comparator<Student>() {
 
        // Method
        public int compare(Student s1, Student s2) {
 
            int rollno1 = s1.getRollno();
            int rollno2 = s2.getRollno();
 
            // For ascending order
            return rollno1 - rollno2;
 
            // For descending order
            // rollno2-rollno1;
        }
    };
 
    // Overriding toString() method to list out student details
    @Override public String toString() {
 
        return "[ rollno=" + rollno + ", name="
               + studentname + ", age=" + studentage + "]";
    }
}
 
// Class 2
// Main class
class Details {
 
    // Main driver method
    public static void main(String args[]) {
 
        // Creating an empty ArrayList of Student type
        ArrayList<Student> arraylist
            = new ArrayList<Student>();
 
        // Adding elements to ArrayList
        arraylist.add(new Student(101, "Zues", 26));
        arraylist.add(new Student(505, "Abey", 24));
        arraylist.add(new Student(809, "Vignesh", 32));
 
        // Sorting based on Student Name
        System.out.println("Student Name Sorting:");
 
        // Using sort() method of Collection class
        Collections.sort(arraylist,
                         Student.StuNameComparator);
 
        for (Student str : arraylist) {
             
            System.out.println(str);
        }
 
        // Now, sorting on Rollno property
        System.out.println("RollNum Sorting:");
 
        Collections.sort(arraylist, Student.StuRollno);
 
        // Iterating over list via for each and
        // printing the elements
        for (Student str : arraylist) {
            System.out.println(str);
        }
    }
}

https://www.geeksforgeeks.org/how-to-sort-an-arraylist-of-objects-by-property-in-java/

Popularity 1/10 Helpfulness 1/10 Language typescript

Source: Grepper

Tags: add arraylist class let typescript using

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Contributed on Feb 04 2023

Pragya Keshap

0 Answers Avg Quality 2/10

Let say there is a Customer class. We add objects of Customer class to an ArrayList. How can we sort the Customer objects in ArrayList by using customer firstName attribute of Customer class?

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