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Java / Constructor

Purpose of default constructor.

Default constructor initializes the instance variables to its default values if not initalized explicitly depending on the type.

For objects, default constructor initializes it to null, int with 0.

In the below example, make String variable is initialized to null, numberofSeats to 0 and isItOldModel to false.

public class Car {
	String make;

	int numberofSeats;

	boolean isItOldModel;

	@Override
	public String toString() {

		return "Car make is " + make + " and it has " + numberofSeats
				+ " seats and is it old model? " + isItOldModel + ".";
	}

	public static void main(String[] args) {

		Car newCar = new Car();
		System.out.println(newCar);

	}

}

Output:

Car make is null and it has 0 seats and is it old model? false.

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