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《Java语言程序设计(基础篇)》(第10版 梁勇 著)
第十一章 练习题答案
11.1
public class Exercise11_01 {
public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.print(\); double side1 = input.nextDouble(); double side2 = input.nextDouble(); double side3 = input.nextDouble();
Triangle triangle = new Triangle(side1, side2, side3);
System.out.print(\); String color = input.nextLine(); triangle.setColor(color);
System.out.print(\); boolean filled = input.nextBoolean(); triangle.setFilled(filled);
System.out.println(\ + triangle.getArea()); System.out.println(\ + triangle.getPerimeter()); System.out.println(triangle); } }
class Triangle extends GeometricObject {
private double side1 = 1.0, side2 = 1.0, side3 = 1.0;
/** Constructor */ public Triangle() { }
/** Constructor */
public Triangle(double side1, double side2, double side3) { this.side1 = side1; this.side2 = side2; this.side3 = side3; }
public double getSide1() { return side1; }
public double getSide2() { return side2; }
public double getSide3() { return side3; }
@Override /** Override method findArea in GeometricObject */ public double getArea() {
double s = (side1 + side2 + side3) / 2;
return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3)); }
@Override /** Override method findPerimeter in GeometricObject */ public double getPerimeter() { return side1 + side2 + side3; }
@Override
public String toString() {
// Implement it to return the three sides
return \ + side1 + \ + side2 + \ + side3; } }
11.2
public class Exercise11_02 {
public static void main(String[] args) { } }
class Person {
protected String name; protected String address; protected String phoneNumber;
protected String email;
@Override
public String toString() { return \; } }
class Student1 extends Person { public static int FRESHMAN = 1; public static int SOPHOMORE = 2; public static int JUNIOR = 3; public static int SENIOR = 4;
protected int status;
@Override
public String toString() { return \; } }
class Employee extends Person { protected String office; protected int salary;
protected Calendar dateHired;
@Override
public String toString() { return \; } }
class Faculty extends Employee { public static int LECTURER = 1;
public static int ASSISTANT_PROFESSOR = 2; public static int ASSOCIATE_PROFESSOR = 3; public static int PROFESSOR = 4;
protected String officeHours; protected int rank;
@Override
public String toString() {
return \; } }
class Staff extends Employee { protected String title;
@Override
public String toString() {
return \ + title; } }
11.3
class Checkings extends Account { protected int overdraftLimit = 5000;
@Override
public String toString() { return \; } }
class Saving extends Account {
protected int overdraftLimit = 5000;
@Override
public String toString() { return \; } }
11.4
import java.util.ArrayList; import java.util.Scanner;
public class Exercise11_04 {
public static void main(String[] args) {
ArrayList
Scanner input = new Scanner(System.in);
System.out.print(\);
int value; do {
value = input.nextInt(); // Read a value from the input
if (value != 0)
list.add(value); // Add the value if it is not in the list } while (value != 0);
// Display the maximum number
System.out.print(\ + max(list)); }
public static Integer max(ArrayList
int result = list.get(0);
for (int i = 1; i < list.size(); i++) if (result < list.get(i)) result = list.get(i);
return result; } }
11.5
import java.util.*;
public class Exercise11_05 {
public static void main(String[] args) {
Course course1 = new Course(\); Course course2 = new Course(\);
course1.addStudent(\); course1.addStudent(\); course1.addStudent(\);
course2.addStudent(\); course2.addStudent(\);
System.out.println(\ + course1.getNumberOfStudents());