Defining Other Constructors

Because there is no method overloading, there can be only one __init__ method. However, multiple methods can be emulated by using optional parameters with default values.

For example, the __init__ method in the following class will set the student’s name to an empty string if the caller supplies no name:

class Student:
    NUM_GRADES = 5 
    def __init__(self, name = ”):
        self.name = name
        self.grades = []
        for i in range(Student.NUM_GRADES):
            self.grades.append(0)
 
Usage:

s1 = Student(‘Mary’)
S2 = Student()

Method overloading allows more than one constructor to be defined, as long as they have different numbers and/or types of arguments.

In the following example, the Student class is given a default constructor that expects no arguments. The new constructor calls the other constructor by using the keyword this and the appropriate argument:

public class Student{
 
    public static final int NUM_GRADES = 5;
 
    private String name;
    private int[] grades;
 
    public Student(String name){
        this.name = name;
        this.grades = new int[NUM_GRADES];
    }
 
    public Student(){
        this(“”);
}

Usage:

Student s1 = new Student(“Mary”);
Student s2 = new Student();