abstractareas.java

使用Swing编写的记事本

abstract class Figure {
	double dim1;
	double dim2;
	Figure(double a,double b) {
		dim1=a;
		dim2=b;
	}
	abstract double area();
}

class Rectangle extends Figure {
	 Rectangle(double a,double b){
		super(a,b);
	}
	double area() {
		System.out.println("Inside Area for Rectangle.");
		return dim1*dim2;
	}
}

class Triangle extends Figure {
	Triangle(double a,double b){
		super(a,b);
	}
	double area(){
		System.out.println("Inside Area for Triangle.");
		return dim1*dim2/2;
	}
}

public class AbstractAreas {
	public static void main(String args[]){
		Rectangle r=new Rectangle(9,5);
		Triangle t=new Triangle(10,8);
		Figure figure;
		figure=r;
		System.out.println("Area is: " + figure.area());
		figure=t;
		System.out.println("Area is: "+ figure.area());
	}
}