编写java程序，程序中定义一个抽象类Area、两个Area类的派生子类RectArea类和RoundArea类、以及实现类Impl
public class Abstractor Area{
public abstractor double area();
}
public class RoundArea{
public RoundArea(double ra){this.area=ra}
private double area;
public double area(){
//求圆的面积
}
}
public class RectArea {
private double width;
private double leng;
public RectArea(double width,double leng){this.width = width; this.leng=leng}
public double area(){
//求长方形的面积
}
}
class ImpleArea{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
area=br.read();
width= br.read();
leng = br.read();
RoundArea ra = new RoundArea(area);
double area1 = ra.area();
RectArea ra2 = new RectArea(width,leng);
double area2 = ra2.area();
}
大概写了下 参考一下吧
public abstract class Shape {public abstract double getArea();public abstract double getLength();}public class Rectangle extends Shape{private double length;private double width;public Rectangle(double length, double width) {super();this.length = length;this.width = width;}@Overridepublic double getArea() {return width*length;}@Overridepublic double getLength() {return width*2+length*2;}}public class Circle extends Shape{private double sidelength;public Circle(double sidelength) {super();this.sidelength = sidelength;}@Overridepublic double getArea() {return Math.pow(sidelength, 2);}@Overridepublic double getLength() {return sidelength*4;}}ublic class Test {public static void main(String[] args) {Rectangle rectangle = new Rectangle(5, 6);double area1=rectangle.getArea();double length2=rectangle.getLength();System.out.println("矩形的面积是:"+area1);System.out.println("矩形的周长是："+length2);Circle circle = new Circle(7);double area = circle.getArea();double length = circle.getLength();System.out.println("正方形的面积是："+area);System.out.println("正方形的周长是"+length);}}//结果：矩形的面积是:30.0矩形的周长是：22.0正方形的面积是：49.0正方形的周长是28.0
abstract class Area{abstract double area();
}
//矩形面积类
class RectArea extends Area{
private double width; //宽
private double height; //高
public RectArea(){
}
public RectArea(double width, double height){
this.width = width;
this.height = height;
}
public double area() {
return this.width * this.height;
}
public double getWidth(){
return this.width;
}
public void setWidth(double width){
this.width = width;
}
public double getHeight(){
return this.height;
}
public void setHeight(double height){
this.height = height;
}
}
//圆面积类
class RoundArea extends Area{
private double radius; //半径
public RoundArea(){
}
public RoundArea(double radius){
this.radius = radius;
}
public double area() {
return Math.PI * this.radius * this.radius;
}
public double getRadius(){
return this.radius;
}
public void setRadius(double radius){
this.radius = radius;
}
}
class ImpleArea{
public void displayArea(){
Scanner scan = new Scanner(System.in);
Area a;
a = new RectArea();
System.out.print("矩形的宽：");
((RectArea)a).setWidth(scan.nextDouble());
System.out.print("矩形的高：");
((RectArea)a).setHeight(scan.nextDouble());
System.out.println("矩形的面积：" + a.area());
a = new RoundArea();
System.out.print("圆的半径：");
((RoundArea)a).setRadius(scan.nextDouble());
System.out.println("圆的面积：" + a.area());
}
}
public class Test {
public static void main(String[] args) {
ImpleArea impl = new ImpleArea();
impl.displayArea();
}
}
像这种简单的程序，你们的课本上应该有吧，如果我们帮你写出来，感觉没多大的意义哦，我记得这个求面积的例子，课本上是有的，自己好好的研究下应该就可以写出来这个程序了，java其实是个很有趣的语言，你只要认真去分析下，你会觉得java太容易了！
好好的了解下java类和接口的定义，继承类，还有java.io，要相信自己哦！~
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