Java高级程序设计：第5章-抽象类和接口.pptx

直接以分号结尾 abstract double perimeter(); } abstract class Rectangle extends Shape{ private double w; private double h; Rectangle(double w, double h) { this.w = w; this.h = h; } void display(){ System.out.println(“我是一个矩形”); } } Rectangle类继承了Shape类，继承了Shape类的抽象方法 perimeter(),但其并未将其覆盖及实现，所以Rectangle类也 必须声明成抽象 class Triangle extends Shape{ private double s1; private double s2; private double s3; public Triangle(double s1, double s2,double s3) { this.s1 = s1; this.s2 = s2; this.s3 = s3; } public double p