《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

《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("Enter three sides: ");

double side1 = input.nextDouble();

double side2 = input.nextDouble();

double side3 = input.nextDouble();

Triangle triangle = new Triangle(side1, side2, side3);

System.out.print("Enter the color: ");

String color = input.nextLine();

triangle.setColor(color);

System.out.print("Enter a boolean value for filled: ");

boolean filled = input.nextBoolean();

triangle.setFilled(filled);

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

System.out.println("The perimeter is "

+ 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"Triangle: side1 = " + side1 + " side2 = " + side2 +

" side3 = " + 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"Person";

}

}

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"Student";

}

}

class Employee extends Person {

protected String office;

protected int salary;

protected Calendar dateHired;

@Override

public String toString() {

return"Employee";

}

}

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() {