java_2017.11.1_继承 接口

1.抽象类

定义一个抽象类Shape，包含求面积area和周长perimeter的两个函数。定义圆Circle类，继承Shape类。定义三角形Triangle，继承Shape类。定义长方形类Square，继承Shape类。并完成以上类的测试。

1.Shape.java

package work02;public abstract class Shape {abstract double area();abstract double perimeter();}

2.Circle01.java

package work02;public class Circle01 extends Shape {double r;public Circle01(double r) {this.r = r;}public double area() {return Math.PI * r * r;}public double perimeter() {return 2 * Math.PI * r;}public String toString() {return "圆形面积：" + area() + " 圆形周长：" + perimeter();}}

3.Triangle.java

package work02;public class Triangle extends Shape {public double len;public Triangle(double len) {super();this.len = len;}public double area() {return Math.sqrt(3) * len * len / 4;}double perimeter() {return 3 * len;}public String toString() {return "正三角形面积：" + area() + " 正三角形周长：" + perimeter();}}

4.Square.java

package work02;public class Square extends Shape {double x, y;public Square(double x, double y) {this.x = x;this.y = y;}double area() {return x * y;}double perimeter() {return 2 * (x + y);}public String toString() {return "长方形面积：" + area() + " 长方形周长：" + perimeter();}}

5.ShapeTest.java

package work02;public class ShapeTest {public static void main(String[]args){Circle01 ce=new Circle01(2);System.out.println(ce);Triangle tr=new Triangle(4);System.out.println(tr);Square sq=new Square(2,3);System.out.println(sq);}}

2.接口

定义一个Shape接口，包含求面积和周长的两个函数。定义一个坐标类Coordinates，包含两个成员变量X坐标和Y坐标。定义圆Circle类，继承Coordinates并实现Shape接口。定义三角形Triangle，继承Coordinates并实现Shape接口。定义长方形类Square，继承Coordinates并实现Shape接口。并完成以上类的测试。

1.Shape.java

package work02;interface Shape {public double area();public double perimeter();}

2.Coordinates.java

package work02;public class Coordinates {public double x,y;public Coordinates(double x, double y) {super();this.x = x;this.y = y;}}

3.Circle01.java

package work02;public class Circle01 extends Coordinates implements Shape {public double r;public Circle01(double x,double y,double r) {super(x,y);this.r = r;}public double area() {return Math.PI * r * r;}public double perimeter() {return 2 * Math.PI * r;}public String toString() {return "圆形面积：" + area() + " 圆形周长：" + perimeter();}}

4.Triangle.java

package work02;public class Triangle extends Coordinates implements Shape {public double len;public Triangle(double x,double y,double len) {super(x,y);this.len = len;}public double area() {return Math.sqrt(3) * len * len / 4;}public double perimeter() {return 3 * len;}public String toString() {return "正三角形面积：" + area() + " 正三角形周长：" + perimeter();}}

5.Square.java

package work02;public class Square extends Coordinates implements Shape {public Square(double x, double y) {super(x,y);//this.x = x;//this.y = y;}public double area() {return x * y;}public double perimeter() {return 2 * (x + y);}public String toString() {return "长方形面积：" + area() + " 长方形周长：" + perimeter();}}

6.ShapeTest.java

package work02;public class ShapeTest {public static void main(String[]args){Shape ce=new Circle01(0,0,2);System.out.println(ce);Shape tr=new Triangle(0,0,4);System.out.println(tr);Shape sq=new Square(2,3);System.out.println(sq);}}/*圆形面积：12.566370614359172 圆形周长：12.566370614359172正三角形面积：6.928203230275509 正三角形周长：12.0长方形面积：6.0 长方形周长：10.0*/