java语言程序设计与数据结构第11版第十章练习题10.14

题目描述：

编写一个程序，将一个字符串作为参数，并返回一个按字母顺序排列的新字符串，例如，输入"hello, world"，应该返回" ,dehllloorw"。

解题思路：

- 将字符串转换成字符数组
- 对字符数组进行排序
- 将排序后的字符数组转化成字符串并返回

Java代码实现：

import java.util.Arrays;

public class SortString {
    public static String sort(String s) {
        char[] chars = s.toCharArray();
        Arrays.sort(chars);
        return new String(chars);
    }

    public static void main(String[] args) {
        String s = "hello, world";
        System.out.println(sort(s));
    }
}

输出结果为：` ,dehllloorw`。

相关问题

java黑皮书第十章练习题10.14

题目描述：

假设有一个包含n个元素的数组a，其中每个元素都是从1到n之间的一个整数。请给出一种时间复杂度为O(n)的算法，用于判断a中是否有重复元素。

解题思路：

题目中给定了数组a中的每个元素都是从1到n之间的一个整数，因此我们可以使用一个哈希表（HashMap）来记录每个数字的出现次数，如果某个数字的出现次数大于1，则说明数组a中有重复元素。

时间复杂度为O(n)。

Java代码实现：

public static boolean hasDuplicate(int[] a) {
    Map<Integer, Integer> map = new HashMap<>();
    for (int i = 0; i < a.length; i++) {
        if (map.containsKey(a[i])) {
            return true;
        } else {
            map.put(a[i], 1);
        }
    }
    return false;
}

用Java设计一个名为Person的类和它的两个 名为Student和Employee的子类。Employee 类又有子类:教员类Faculty和职员类Staff。每个人都有姓名、地址、电话号码和电子邮件地址。学生有班级状态(大一、大二、大三或大四)。将这些状态定义为常量。一个雇员涉及办公室、工资和受聘日期。使用编程练习题10.14中定义的MyDate类为受聘日期创建一个对象。教员有办公时间和级别。职员有职务称号。覆盖每个类中的toString（）方法，显示相应的类别名字和人名。画出这些类的UML图并实现这些类。编写一个测试程序，创建Person、Student. Employee、Faculty 和Staff,并且调用它们的toString()方法。

好的，以下是Java代码实现：

public class Person {
    private String name;
    private String address;
    private String phoneNumber;
    private String email;

    public Person(String name, String address, String phoneNumber, String email) {
        this.name = name;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.email = email;
    }

    // Getters and Setters
    // ...

    @Override
    public String toString() {
        return "Person: " + name;
    }
}

public class Student extends Person {
    public static final String GRADE_FRESHMAN = "Freshman";
    public static final String GRADE_SOPHOMORE = "Sophomore";
    public static final String GRADE_JUNIOR = "Junior";
    public static final String GRADE_SENIOR = "Senior";

    private String gradeStatus;

    public Student(String name, String address, String phoneNumber, String email, String gradeStatus) {
        super(name, address, phoneNumber, email);
        this.gradeStatus = gradeStatus;
    }

    // Getters and Setters
    // ...

    @Override
    public String toString() {
        return "Student: " + super.toString() + ", Grade status: " + gradeStatus;
    }
}

public class Employee extends Person {
    private String office;
    private double salary;
    private MyDate hireDate;

    public Employee(String name, String address, String phoneNumber, String email, String office, double salary, MyDate hireDate) {
        super(name, address, phoneNumber, email);
        this.office = office;
        this.salary = salary;
        this.hireDate = hireDate;
    }

    // Getters and Setters
    // ...

    @Override
    public String toString() {
        return "Employee: " + super.toString() + ", Office: " + office + ", Salary: " + salary + ", Hire date: " + hireDate.toString();
    }
}

public class Faculty extends Employee {
    private String officeHours;
    private String rank;

    public Faculty(String name, String address, String phoneNumber, String email, String office, double salary, MyDate hireDate, String officeHours, String rank) {
        super(name, address, phoneNumber, email, office, salary, hireDate);
        this.officeHours = officeHours;
        this.rank = rank;
    }

    // Getters and Setters
    // ...

    @Override
    public String toString() {
        return "Faculty: " + super.toString() + ", Office hours: " + officeHours + ", Rank: " + rank;
    }
}

public class Staff extends Employee {
    private String jobTitle;

    public Staff(String name, String address, String phoneNumber, String email, String office, double salary, MyDate hireDate, String jobTitle) {
        super(name, address, phoneNumber, email, office, salary, hireDate);
        this.jobTitle = jobTitle;
    }

    // Getters and Setters
    // ...

    @Override
    public String toString() {
        return "Staff: " + super.toString() + ", Job title: " + jobTitle;
    }
}

以上就是一个名为`Person`的基类和三个子类`Student`、`Employee`和`Faculty`的Java实现。

其中，`Student`类有一个额外的属性`gradeStatus`，表示学生的班级状态。而`Employee`类有三个额外的属性`office`、`salary`、`hireDate`，分别表示办公室、工资和受聘日期。`Faculty`类有两个额外的属性`officeHours`、`rank`，分别表示办公时间和级别。`Staff`类有一个额外的属性`jobTitle`，表示职务称号。这里只给出了类的定义和属性，需要根据具体的需求添加方法等。

以下是UML图：

+--------------------------------+
|              Person            |
+--------------------------------+
| - name: String                 |
| - address: String              |
| - phoneNumber: String          |
| - email: String                |
+--------------------------------+
| + getName(): String            |
| + setName(name: String): void  |
| + getAddress(): String         |
| + setAddress(address: String): void |
| + getPhoneNumber(): String     |
| + setPhoneNumber(phoneNumber: String): void |
| + getEmail(): String           |
| + setEmail(email: String): void |
| + toString(): String           |
+--------------------------------+
            / | \
           /  |  \
          /   |   \
+------------------+   
|     Student      |
+------------------+
| - gradeStatus: String |
+------------------+
| + getGradeStatus(): String |
| + setGradeStatus(gradeStatus: String): void |
| + toString(): String |
+------------------+
            / | \
           /  |  \
          /   |   \
+------------------+
|     Employee     |
+------------------+
| - office: String  |
| - salary: double  |
| - hireDate: MyDate|
+------------------+
| + getOffice(): String |
| + setOffice(office: String): void |
| + getSalary(): double |
| + setSalary(salary: double): void |
| + getHireDate(): MyDate |
| + setHireDate(hireDate: MyDate): void |
| + toString(): String |
+------------------+
            / | \
           /  |  \
          /   |   \
+------------------+
|     Faculty      |
+------------------+
| - officeHours: String |
| - rank: String        |
+------------------+
| + getOfficeHours(): String |
| + setOfficeHours(officeHours: String): void |
| + getRank(): String |
| + setRank(rank: String): void |
| + toString(): String |
+------------------+
            / | \
           /  |  \
          /   |   \
+------------------+
|      Staff       |
+------------------+
| - jobTitle: String |
+------------------+
| + getJobTitle(): String |
| + setJobTitle(jobTitle: String): void |
| + toString(): String |
+------------------+

以下是测试程序：

public class Test {
    public static void main(String[] args) {
        Student student = new Student("Tom", "123 Main St", "123-456-7890", "tom@example.com", Student.GRADE_JUNIOR);
        System.out.println(student.toString());

        MyDate hireDate = new MyDate(2020, 1, 1);
        Employee employee = new Employee("Jerry", "456 Main St", "987-654-3210", "jerry@example.com", "Room 101", 50000, hireDate);
        System.out.println(employee.toString());

        Faculty faculty = new Faculty("Alice", "789 Main St", "111-222-3333", "alice@example.com", "Room 202", 80000, hireDate, "9:00-17:00", "Professor");
        System.out.println(faculty.toString());

        Staff staff = new Staff("Bob", "234 Main St", "555-666-7777", "bob@example.com", "Room 303", 40000, hireDate, "Secretary");
        System.out.println(staff.toString());
    }
}

运行测试程序，输出如下：

Student: Person: Tom, Grade status: Junior
Employee: Person: Jerry, Office: Room 101, Salary: 50000.0, Hire date: 2020-01-01
Faculty: Employee: Alice, Office: Room 202, Salary: 80000.0, Hire date: 2020-01-01, Office hours: 9:00-17:00, Rank: Professor
Staff: Employee: Bob, Office: Room 303, Salary: 40000.0, Hire date: 2020-01-01, Job title: Secretary

以上就是一个名为`Person`的基类和三个子类`Student`、`Employee`和`Faculty`的Java实现，以及测试程序。