Java Multi-State computing Area main function call method

public static void Main (string[] args) {
Shape shape;
Scanner input = new Scanner (system.in);
System.out.println ("Select the graphic (1, Circle 2, Rectangle 3, triangle)");
int a = Input.nextint ();
if (a = = 1) {
System.out.println ("Please enter the circular side length:");
Double r = input.nextdouble ();
Shape = new Round (r);
Shape.area ();
}else if (a = = 2) {
System.out.println ("Please enter the bottom of the rectangle:");
Double bottom = input.nextdouble ();
System.out.println ("Please enter the height of the rectangle:");
Double high = input.nextdouble ();
Shape = new Rectangle (bottom, high);
Shape.area ();
}else if (a = = 3) {
System.out.println ("Please enter the bottom of the triangle:");
Double bottom = input.nextdouble ();
System.out.println ("Please enter the height of the triangle:");
Double high = input.nextdouble ();
Shape = new Triangle (bottom, high);
Shape.area ();
}
Input.close ();

}

Java Multi-State computing Area main function call method