java语言程序设计基础篇第十版第十三章练习答案

01

public class Exercise13_01 {

public static void main(String[] args) {

TriangleNew triangle = new TriangleNew(1, 1.5, 1);

triangle.setColor("yellow");

triangle.setFilled(true);

System.out.println(triangle);

System.out.println("The area is " + triangle.getArea());

System.out.println("The perimeter is "

+ triangle.getPerimeter());

System.out.println(triangle);

}

}

classTriangleNew extends GeometricObject {

private double side1 = 1.0, side2 = 1.0, side3 = 1.0;

/** Constructor */

publicTriangleNew() {

}

/** Constructor */

publicTriangleNew(double side1, double side2, double side3) { this.side1 = side1;

this.side2 = side2;

this.side3 = side3;

}

/** Implement the abstract method findArea in GeometricObject */ public double getArea() {

double s = (side1 + side2 + side3) / 2;

returnMath.sqrt(s * (s - side1) * (s - side2) * (s - side3));

}

/** Implement the abstract method findCircumference in

* GeometricObject

**/

public double getPerimeter() {

return side1 + side2 + side3;

}

@Override

public String toString() {

// Implement it to return the three sides

return "TriangleNew: side1 = " + side1 + " side2 = " + side2 + " side3 = " + side3;

}

}

02

importjava.util.ArrayList;

public class Exercise13_02 {

public static void main(String[] args) {

ArrayList list = new ArrayList();

list.add(14);

list.add(24);

list.add(4);

list.add(42);

list.add(5);

shuffle(list);

for (inti = 0; i

System.out.print(list.get(i) + " ");

}

public static void shuffle(ArrayList list) {

for (inti = 0; i

int index = (int)(Math.random() * list.size());

Number temp = list.get(i);

list.set(i, list.get(index));

list.set(index, temp);

}

}

}

03

importjava.util.ArrayList;

public class Exercise13_03 {

public static void main(String[] args) {

ArrayList list = new ArrayList();

list.add(14);

list.add(24);

list.add(4);

list.add(42);

list.add(5);

sort(list);

for (inti = 0; i

System.out.print(list.get(i) + " ");

}

public static void sort(ArrayList list) {

for (inti = 0; i

// Find the minimum in the list[i..list.length-1]

Number currentMin = list.get(i);

intcurrentMinIndex = i;

for (int j = i + 1; j

if (currentMin.doubleValue() >list.get(j).doubleValue()) { currentMin = list.get(j);

currentMinIndex = j;

}

}

// Swap list.get(i) with list.get(currentMinIndex) if necessary; if (currentMinIndex != i) {

list.set(currentMinIndex, list.get(i));

list.set(i, currentMin);

}

}

}

}

04

importjava.util.*;

public class Exercise13_04 {

staticMyCalendar calendar = new MyCalendar();

public static void main(String[] args) {

int month = calendar.get(MyCalendar.MONTH) + 1;

int year = calendar.get(MyCalendar.YEAR);

if (args.length> 2)

System.out.println("Usage java Exercise13_04 month year");

else if (args.length == 2) {

//use user-defined month and year

year = Integer.parseInt(args[1]);

month = Integer.parseInt(args[0]);

calendar.set(Calendar.YEAR, year);

calendar.set(Calendar.MONTH, month - 1);

}

else if (args.length == 1) {

//use user-defined month for the current year

month = Integer.parseInt(args[0]);

calendar.set(Calendar.MONTH, month-1);

}

//set date to the first day in a month

calendar.set(Calendar.DATE, 1);

//print calendar for the month

printMonth(year, month);

}

static void printMonth(int year, int month) {

//get start day of the week for the first date in the month intstartDay = getStartDay();

//get number of days in the month intnumOfDaysInMonth = calendar.daysInMonth();

//print headings

printMonthTitle(year, month);

//print body

printMonthBody(startDay, numOfDaysInMonth);

}

staticintgetStartDay() {

returncalendar.get(Calendar.DAY_OF_WEEK);

}

static void printMonthBody(intstartDay, intnumOfDaysInMonth) { //print padding space before the first day of the month

inti = 0;

for (i = 0; i< startDay-1; i++)

System.out.print(" ");

for (i = 1; i<= numOfDaysInMonth; i++) {

if (i< 10)

System.out.print(" "+i);

else

System.out.print(" "+i);

if ((i + startDay - 1) % 7 == 0)

System.out.println();

}

System.out.println("");

}

static void printMonthTitle(int year, int month) {

System.out.println(" "+calendar.getMonthName()+", "+year); System.out.println("-----------------------------");

System.out.println(" Sun Mon Tue Wed Thu Fri Sat");

}

}

05

public class Exercise13_05 {

// Main method

public static void main(String[] args) {

// Create two comparable circles

Circle1 circle1 = new Circle1(5);

Circle1 circle2 = new Circle1(4);

// Display the max circle

Circle1 circle = (Circle1) GeometricObject1.max(circle1, circle2); System.out.println("The max circle's radius is " + circle.getRadius()); System.out.println(circle);

}

}

abstract class GeometricObject1 implements Comparable { protected String color;

protected double weight;

// Default construct

protected GeometricObject1() {

color = "white";

weight = 1.0;

}

// Construct a geometric object

protected GeometricObject1(String color, double weight) {

this.color = color;

this.weight = weight;

// Getter method for color

public String getColor() {

return color;

}

// Setter method for color

public void setColor(String color) {

this.color = color;

}

// Getter method for weight

public double getWeight() {

return weight;

}

// Setter method for weight

public void setWeight(double weight) {

this.weight = weight;

}

// Abstract method

public abstract double getArea();

// Abstract method

public abstract double getPerimeter();

publicintcompareTo(GeometricObject1 o) {

if (getArea()

return -1;

else if (getArea() == o.getArea())

return 0;

else

return 1;

}

public static GeometricObject1 max(GeometricObject1 o1, GeometricObject1 o2) { if (https://www.doczj.com/doc/d618531446.html,pareTo(o2) > 0)

return o1;

else

return o2;

}

}

// Circle.java: The circle class that extends GeometricObject

class Circle1 extends GeometricObject1 {

protected double radius;

// Default constructor

public Circle1() {

this(1.0, "white", 1.0);

}

// Construct circle with specified radius

public Circle1(double radius) {

super("white", 1.0);

this.radius = radius;

}

// Construct a circle with specified radius, weight, and color

public Circle1(double radius, String color, double weight) {

super(color, weight);

this.radius = radius;

}

// Getter method for radius

public double getRadius() {

return radius;

}

// Setter method for radius

public void setRadius(double radius) {

this.radius = radius;

}

// Implement the findArea method defined in GeometricObject public double getArea() {

return radius * radius * Math.PI;

}

// Implement the findPerimeter method defined in GeometricObject public double getPerimeter() {

return 2 * radius * Math.PI;

}

// Override the equals() method defined in the Object class publicboolean equals(Circle1 circle) {

returnthis.radius == circle.getRadius();

}

@Override

public String toString() {

return "[Circle] radius = " + radius;

}

@Override

publicintcompareTo(GeometricObject1 o) {

if (getRadius() > ((Circle1) o).getRadius())

return 1;

else if (getRadius() < ((Circle1) o).getRadius())

return -1;

else

return 0;

}

}

06

public class Exercise13_06 {

// Main method

public static void main(String[] args) {

// Create two comarable rectangles

ComparableCircle circle1 = new ComparableCircle(5);

ComparableCircle circle2 = new ComparableCircle(15);

// Display the max rect

ComparableCircle circle3 = (ComparableCircle)Max.max(circle1, circle2); System.out.println("The max circle's radius is " + circle3.getRadius());

System.out.println(circle3);

}

}

classComparableCircle extends Circle implements Comparable { /** Construct a ComparableRectangle with specified properties */ publicComparableCircle(double radius) {

super(radius);

}

@Override

publicintcompareTo(ComparableCircle o) {

if (getRadius() >o.getRadius())

return 1;

else if (getRadius()

return -1;

else

return 0;

}

}

//Max.java: Find a maximum object

class Max {

/** Return the maximum of two objects */

public static ComparableCircle max

(ComparableCircle o1, ComparableCircle o2) {

if (https://www.doczj.com/doc/d618531446.html,pareTo(o2) > 0)

return o1;

else

return o2;

}

}

07

public class Exercise13_07 {

public static void main(String[] args) {

GeometricObject[] objects = {new Square(2), new Circle(5), new Square(5), new Rectangle(3, 4), new Square(4.5)};

for (inti = 0; i

System.out.println("Area is " + objects[i].getArea());

if (objects[i] instanceof Colorable)

((Colorable)objects[i]).howToColor();

}

}

}

interface Colorable {

voidhowToColor();

}

class Square extends GeometricObject implements Colorable {

private double side;

public Square(double side) {

this.side = side;

}

@Override

public void howToColor() {

System.out.println("Color all four sides");

}

@Override

public double getArea() {

return side * side;

}

@Override

public double getPerimeter() {

return 4 * side;

}

}

08

importjava.util.ArrayList;

public class Exercise13_08 {

public static void main(String[] args) {

MyStack1 stack = new MyStack1();

stack.push("S1");

stack.push("S2");

stack.push("S");

MyStack1 stack2 = (MyStack1) (stack.clone()); stack2.push("S1");

stack2.push("S2");

stack2.push("S");

System.out.println(stack.getSize());

System.out.println(stack2.getSize());

}

}

class MyStack1 implements Cloneable { privateArrayList