（1）修改实验五中的Triangle类，使其继承自GeometricObject并实现Comparable接口。覆盖Object类中的equals方法，当两个三角形的面积相等时，则两个三角形是相同的。
public class GeometricObject {
private String color = "White";
private boolean filled;
private java.util.Date dateCreated;
public GeometricObject() {
dateCreated = new java.util.Date();
}
public GeometricObject(String color,boolean filled) {
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public boolean isFilled() {
return filled;
}
public void setFilled(boolean filled) {
this.filled = filled;
}
public java.util.Date getDateCreated(){
return dateCreated;
}
public String toString() {
return "created on " + dateCreated + "\ncolor:" + color + " and filled:" + filled;
}
}
public class Triangle extends GeometricObject implements Comparable<Triangle>{
private double side1;
private double side2;
private double side3;
Triangle(){
}
Triangle(double s1,double s2,double s3){
side1 = s1;
side2 = s2;
side3 = s3;
}
public double getSide1() {
return side1;
}
public void setSide1(double s1) {
side1 = s1;
}
public double getSide2() {
return side2;
}
public void setSide2(double s2) {
side2 = s2;
}
public double getSide3() {
return side3;
}
public void setSide3(double s3) {
side3 = s3;
}
public double getArea() {
double a = (side1+side2+side3)/2;
return Math.sqrt(a*(a-side1)*(a-side2)*(a-side3));
}
public double gerPerimeter() {
return side1+side2+side3;
}
public String toString() {
return "Creat on "+super.getDateCreated()+"\ncolor: "+super.getColor()+"\nSide1:"+this.side1+"\nSide2:"+
this.side2+"\nSide3:"+this.side3+"\nArea:"+this.getArea()+"\nPerimeter:" + this.gerPerimeter();
}
public boolean equal(Triangle A) {
return this.getArea() == A.getArea();
}
@Override
public int compareTo(Triangle A) {
if(this.getArea()>A.getArea())
return 1;
else if(this.getArea()<A.getArea())
return -1;
else
return 0;
}
}
public class TriangleTest {
public static void main(String[] args) {
// TODO 自动生成的方法存根
Triangle t1 = new Triangle(3,4,5);
Triangle t2 = new Triangle(5,12,13);
System.out.println(t1.toString());
System.out.println(t2.toString());
System.out.println(t1.equal(t2));
System.out.println(t1.compareTo(t2));
}
}
（2）编写一个实现Sortable接口的类PointSorter，该类能够完成对坐标点的排序（按照坐标点到原点（0，0）的距离从大到小排列）。
public class Point {
double x,y;
double distance;
Point(){
}
Point(double x,double y){
this.x = x;
this.y = y;
this.distance = Math.sqrt(x*x+y*y);
}
}
class Sort {
Sortable S;
Sort(){
}
Sort(Sortable S){
this.S = S;
}
public Point[] sort(Point[] P) {
for(int i = 0;i<P.length-1;i++)
for(int j = 0;j<P.length-1;j++) {
int temp = S.sort(P[i], P[j]);
if(temp >0) {
Point q = P[i];
P[i] = P[j];
P[j] = q;
}
}
return P;
}
}
class PointSorter implements Sortable{
@Override
public int sort(Object A, Object B) {
Point p1 = (Point)A;
Point p2 = (Point)B;
if(p1.distance>p2.distance)
return 1;
return -1;
}
}
public interface Sortable {
public int sort(Object A,Object B);
}
public class PointTest {
public static void main(String[] args) {
Point p1 = new Point(4,2);
Point p2 = new Point(1,3);
Point p3 = new Point(1,4);
Point p4 = new Point(5,5);
Point p5 = new Point(1,1);
Point[] p = {p1,p2,p3,p4,p5};
PointSorter pointsorter = new PointSorter();
Sort sort = new Sort(pointsorter);
Point[] newp = sort.sort(p);
for(int i = 0;i<5;i++) {
System.out.println(newp[i].x +" "+newp[i].y+" "+newp[i].distance);
}
}
}
（3）根据以下类图，采用桥接模式编程验证面向对象的“开-闭”原则。
public class GreenTea implements TeaKind{
private double price;
GreenTea(){
}
GreenTea(double price){
this.price = price;
}
@Override
public double getPrice() {
return price;
}
}
public class RedTea implements TeaKind{
private double price;
RedTea(){
}
RedTea(double price){
this.price = price;
}
@Override
public double getPrice() {
return price;
}
}
public class BlackTea implements TeaKind{
private double price;
BlackTea(){
}
BlackTea(double price){
this.price = price;
}
@Override
public double getPrice() {
// TODO 自动生成的方法存根
return price;
}
}
public class MediumCup implements TeaSize{
public TeaKind teakind;
MediumCup(TeaKind teakind){
this.teakind = teakind;
}
@Override
public double getprice() {
return 1.5*teakind.getPrice();
}
}
public class SuperCup implements TeaSize{
public TeaKind teakind;
SuperCup(TeaKind teakind){
this.teakind = teakind;
}
@Override
public double getprice() {
return 2.5*teakind.getPrice();
}
}
public class SmallCup implements TeaSize{
public TeaKind teakind;
SmallCup(TeaKind teakind){
this.teakind = teakind;
}
@Override
public double getprice() {
return teakind.getPrice();
}
}
public interface TeaSize {
public double getprice();
}
public interface TeaKind {
public double getPrice();
}
import java.util.Scanner;
public class TeaTest {
public static void main(String[] args) {
// TODO 自动生成的方法存根
RedTea redtea = new RedTea(2);
GreenTea greentea = new GreenTea(3);
BlackTea blacktea = new BlackTea(4);
System.out.println("请选择您要的饮料:");
System.out.println("1.红茶 2.绿茶 3.黑茶");
Scanner input = new Scanner(System.in);
int number1 = input.nextInt();
System.out.println("请选择您要的规格:");
System.out.println("1.小杯 2.中杯 3.大杯");
int number2 = input.nextInt();
switch(number1) {
case 1:
switch(number2) {
case 1:System.out.print(new SmallCup(redtea).getprice());break;
case 2:System.out.print(new MediumCup(redtea).getprice());break;
case 3:System.out.print(new SuperCup(redtea).getprice());break;
};break;
case 2:
switch(number2) {
case 1:System.out.print(new SmallCup(greentea).getprice());break;
case 2:System.out.print(new MediumCup(greentea).getprice());break;
case 3:System.out.print(new SuperCup(greentea).getprice());break;
};break;
case 3:
switch(number2) {
case 1:System.out.print(new SmallCup(blacktea).getprice());break;
case 2:System.out.print(new MediumCup(blacktea).getprice());break;
case 3:System.out.print(new SuperCup(blacktea).getprice());break;
};break;
}
input.close();
}
}