• Each class must have at least one constructor
• If no constructor is defined, a default constructor is generated by compiler to enable Car c = new Car()
• If any constructors are defined, must to use a constructor to initialize an object

public class Car
{
	private String maker;

	public Car()
	{
		maker = "Unknown";
	}

	public Car(String maker)
	{
		this.maker = maker;
	}

	public String toString()
	{
		return "Maker: "+this.maker;
	}

	public static void main(String args[])
	{
		Car c = new Car();

		System.out.println(c);
	}
}
			

public class Car
{
	private String maker;

	//copy constructor
	public Car(Car c)
	{
		maker = c.maker;
	}

	//constructor
	public Car(String maker)
	{
		this.maker = maker;
	}

	public String toString()
	{
		return "Maker: "+this.maker;
	}

	public static void main(String args[])
	{
		Car c = new Car("Buick");
		Car c2 = new Car(c);

		System.out.println(c2);
	}
}
			

public class Car
{
	private String maker;
	private String color;

	//int block
	{
		System.out.println("Int block is implemented before any constructor");
	}

	//constructor
	public Car(String m, String c)
	{
		maker = m;
		color = c;
	}

	public Car(String maker)
	{
		this(maker, "unknown");
	}

	public Car()
	{
		this("unknown");
	}

	public String toString()
	{
		return "Maker: "+this.maker+" Color: "+this.color;
	}

	public static void main(String args[])
	{
		Car c = new Car("Buick");

		System.out.println(c);
	}
}
			

• Geeksforgeeks