自定义形状类(继承的运用)

百威

/** *  * 自定义图形的基类 */public abstract class MyShape {/**形状的名字*/protected String name;/* * protected访问控制符表示只有本类和子类能够访问该属性 *//**抽象方法，获取形状的周长*/public abstract double getGrith();/**抽象方法，获取形状的面积*/public abstract double getArea();/**抽象方法，输出形状*/public abstract String toString();public String getName() {return name;}public void setName(String name) {this.name = name;}}

/** *  * 三角形 */public class Triangle extends MyShape{private double sideA;private double sideB;private double sideC;public static final String SIDEERR = "三角形的边长不能够小于0！";public static final String SHAPEERR = "三角形的两边之和必须大于第三边";public Triangle(){init();}public Triangle(double a,double b,double c){/* * 如果给定的三条边能够组成三角形，便用给定的边长构成三角形 */}private void init(){this.sideA = 3;this.sideB = 4;this.sideC = 5;}private boolean isTrianglelegal(double a,double b,double c){//三条边的长度必须大于0if((a<=0) || (b<=0) || (c<=0)){System.out.println(SIDEERR);return false;}else if((a+b<c) || (a+c<b) || (b+c<a)){//两边之和必须大于第三边System.out.println(SHAPEERR);return false;}return true;}public double getArea() {double s = (this.sideA + this.sideB + this.sideC) /2;return Math.sqrt(s*(s - this.sideA) * (s-this.sideB) * (s-this.sideC));}public double getGrith() {return this.sideA + this.sideB + this.sideC;}public String toString() {// TODO Auto-generated method stubreturn "三角形的名字是：" + this.name + " ,它的三条边的边长分别是：" + this.sideA + ", " + this.sideB + ", " + this.sideC;}public double getSideA() {return sideA;}public void setSideA(double sideA) {if(this.isTrianglelegal(sideA, this.sideB, this.sideC)){this.sideA = sideA;}}public double getSideB() {return sideB;}public void setSideB(double sideB) {if(this.isTrianglelegal(this.sideA, sideB, this.sideC)){this.sideB = sideB;}}public double getSideC() {return sideC;}public void setSideC(double sideC){if(this.isTrianglelegal(this.sideA, this.sideB, sideC)){this.sideC = sideC;}}public static void main(String[] args){Triangle test = new Triangle();test.setName("myTriangle");System.out.println(test.toString());System.out.println("三角形的周长是：" + test.getGrith());System.out.println("三角形的面积是：" + test.getArea());}}
/** *  * 长方形 */public class Rectangle extends MyShape {private double length;private double width;public static final String SIDEERR = "长方形的长和宽必须大于0！";public Rectangle(){init();}public Rectangle(double a,double b){if((a<=0) || (b<=0)){System.out.println(SIDEERR);init();}else{this.length = a;this.width = b;}}private void init(){this.length = 5;this.width = 4;}public double getArea() {return this.length * this.width;}public double getGrith() {return (this.length + this.width)/2;}public String toString() {return "矩形的名字为：" + this.name + ",长为" + this.length + ",宽为 " + this.width;}public double getLength() {return length;}public void setLength(double length) {if(length>0){this.length = length;}else{System.out.println(SIDEERR);}}public double getWidth() {return width;}public void setWidth(double width) {if(width>0){this.width = width;}else{System.out.println(SIDEERR);}}public static void main(String [] args){Rectangle test = new Rectangle();test.setName("myRectangle");;System.out.println(test.toString());System.out.println("矩形的周长是：" + test.getGrith());System.out.println("矩形的面积是：" + test.getArea());}}