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いくつかのプライベート フィールドを出力するために toString() メソッドを使用しようとしています。ただし、適切なクラスのオブジェクトを印刷メソッドに送信しようとすると、フィールドを何に変更しても、各フィールドのデフォルト値のみが出力されます。どんな助けでも大歓迎です:) toString() メソッドを持つクラスは次のとおりです(また、ゲッターが由来する別のクラスをオーバーライドします)。申し訳ありませんが、この投稿の編集が遅くなります。ここのテキストエディタに慣れていません。

人物クラス

public class Person
{
// Declare all the fields as strings
private String firstName = "", lastName = "", address = "", zipcode = "",
        phone = "";  // There are accessors and mutators for these as well
public String toString()
{
        String str = "First name: " + firstName + "...Last name: " + lastName + 
                "... Street address: " + address + "... Zipcode: " + zipcode + 
                "... Phone number: " + phone;

    return str;
}

学生クラス

  public class Student extends Person
  {
    // declare fields that are not in Person
    private String major = "";
    private double gpa;

        // Declare accessor and mutator methods for the fields
        public String getMajor()
        {
            return major;
        }

    public void setMajor(String major)
    {
        this.major = major;
    }

    public double getGpa()
    {
        return gpa;
    }

    public void setGpa(double gpa)
    {
        this.gpa = gpa;
    }


    // Create a toString method that overrides the one in Person
    public String toString()
    {
        String str = "First name: " + getFirstName() + "...Last name: " + 
                getLastName() + "... Street address: " + getAddress() + 
                "... Zipcode: " + getZipcode() + "... Phone number: " +
                getPhone() + "... Grade point average: " + getGpa() +
                "...Major: " + getMajor();

        return str;
    }
}

これがメインクラス全体です...宿題なので、その多くは退屈なコードですが、主なアイデアは次のとおりです。「4つの「通常の」CollegeEmployees、3つのFaculty、および 7 人の生徒. 入力する人のデータのタイプを指定するようにユーザーに求める ('C'、'F'、または 'S') か、ユーザーが終了できるようにする ('Q'). ユーザーが続行することを選択している間(つまり、終了しません)、適切なタイプの個人のデータ入力を受け入れます. ユーザーが 4 人を超える大学の従業員、3 人の教職員、または 7 人の学生のデータを入力しようとすると、エラー メッセージが表示されます. ユーザーが終了すると、 「大学生」、「教職員」、または「学生」という適切な見出しの下に、個人の各グループを一覧表示するレポートを画面に表示します。ユーザーがセッション中に 1 つまたは複数のタイプの個人のデータを入力しなかった場合、適切な見出しの下に適切なメッセージを表示します。

メインクラス

import java.util.Scanner;  // Needed for Scanner class

public class CollegeList
{

/**
 * @param args the command line arguments
 */
public static void main(String[] args)
{
    // Declare the arrays of people
    Person[] people = new Person[14];

    // These three arrays are being made to print out the types of people
    // at the end neatly
    Faculty[] fArray = new Faculty[4];
    Student[] sArray = new Student[7];
    CollegeEmployee[] cArray = new CollegeEmployee[3];

    // Prompt for users input
    System.out.print("Please choose the type of person you are entering " +
            "data for.\nFor a student enter \"S\"; for a faculty member " +
            "enter \"F\"; for a college employee enter \"C\"; and to quit " 
            + "enter \"Q\": ");

    Scanner keyboard = new Scanner(System.in);
    String type = keyboard.next();  // the type of person
    System.out.println();

    // initialize counts of persons so that user does not enter more
    int facultyCount = 0;
    int studentCount = 0;
    int employeeCount = 0;

    // initialize index of the array to 0
    int index = 0;

    // continue until the user enters Q or until one of the types of people
    // overflows or until all 14 elements are taken up
    while (!type.equals("Q") && (facultyCount <= 3) && (studentCount <= 7)
            && (employeeCount <= 4) && (index < 14))
    {
        if(type.equals("S") && !type.equals("Q")) // Enter info for student
        {
            // Give the indexes the adresses
            people[index] = new Student();
            sArray[studentCount] = new Student();

            // Set the info
            personInfo(people[index]);
            studentInfo((Student)people[index]);
            System.out.println("\n");

            // Increment the counts
            studentCount++;
            index++;
        }

        else if(type.equals("C") && !type.equals("Q")) // Enter info for
        {                                              // college employee
            // Give the indexes the adresses
            people[index] = new CollegeEmployee();
            cArray[employeeCount] = new CollegeEmployee();

            // Set the info
            personInfo(people[index]);
            employeeInfo((CollegeEmployee)people[index]);
            System.out.println("\n");

            // Increment the counts
            employeeCount++;
            index++;
        }

        else if(type.equals("F") && !type.equals("Q")) // enter info for faculty
        {
            // Give the indexes the adresses
            people[index] = new Faculty();
            fArray[facultyCount] = new Faculty();

            // Set the info
            personInfo(people[index]);
            employeeInfo((CollegeEmployee)people[index]);
            facultyInfo((Faculty)people[index]);
            System.out.println("\n");

            // increment the counts
            facultyCount++;
            index++;
        }

        System.out.print("Please enter the next person type (S, C, F, " +
                "or Q): ");
        type = keyboard.next();
    }

    // Displays error message then closes program if there was overflow
    if ((facultyCount > 3) || (studentCount > 7) || (employeeCount > 4))
    {
        System.out.println("Too much data for one type of  person. Goodbye.");
        System.exit(0);
    }


    // Print the data for all of the college employees
    System.out.println("\n\n");
    System.out.println("THE COLLEGE EMPLOYEES");
    for (int i = 0; i < employeeCount; i++)
    {
        System.out.println(cArray[i]);
        System.out.println("\n");
    }
    // Determines if not all of the personS type was filled
    if (employeeCount != 4)
    {
        System.out.println("There are " + (4 - employeeCount) + " employees"
                + " who are not recorded.");
    }



    // Print the data for all of the faculty
    System.out.println("\n\n");
    System.out.println("THE FACULTY");
    for (int i = 0; i < facultyCount; i++)
    {
        System.out.println(fArray[i]);
        System.out.println("\n");
    }
    // Determines if not all of the person type was filled
    if (facultyCount != 3)
    {
        System.out.println("There are " + (3 - facultyCount) + " faculty "
                + "members who are not recorded.");
    }



    // Print the data for all of the students
    System.out.println("\n\n");
    System.out.println("THE STUDENTS");
    for (int i = 0; i < studentCount; i++)
    {
        System.out.println(sArray[i]);
        System.out.println("\n");
    }
    // Determines if not all of the person type was filled
    if (studentCount != 7)
    {
        System.out.println("There are " + (7 - studentCount) + " students "
                + "who are not recorded.");
    }
}

// prompts the user for data input that is universal to all the people
public static void personInfo(Person p)
{
    Scanner keyboard = new Scanner(System.in);

    System.out.print("First name: ");
    String fName = keyboard.nextLine();
    System.out.println();

    System.out.print("Last name: ");
    String lName = keyboard.nextLine();
    System.out.println();

    System.out.print("Street address: ");
    String address = keyboard.nextLine();
    System.out.println();

    System.out.print("Zipcode: ");
    String zipcode = keyboard.nextLine();
    System.out.println();

    System.out.print("Phone number: ");
    String phone = keyboard.nextLine();
    System.out.println();

    // Sets the data accordingly
    p.setFirstName(fName);
    p.setLastName(lName);
    p.setAddress(address);
    p.setZipcode(zipcode);
    p.setPhone(phone);
}

// Sets the data for student fields
public static void studentInfo(Student s)
{
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Grade point average: ");
    double gpa = keyboard.nextDouble();
    System.out.println();

    System.out.print("Major: ");
    String major = keyboard.next();
    System.out.println();

    // Set the data accordingly
    s.setGpa(gpa);
    s.setMajor(major);
}

// Sets the data for Faculty fields
public static void facultyInfo(Faculty f)
{
    Scanner keyboard = new Scanner(System.in);

    System.out.println("Is the faculty tenured (\"yes\" or \"no)\"?");
    String tenured = keyboard.next();

    // set the data accordingly
    switch (tenured)
    {
        case "yes" :
            f.setTenured(true);
            break;
        case "no" :
            f.setTenured(false);
            break;
    }
}

// Sets the info for CollegeEmployee fields
public static void employeeInfo(CollegeEmployee c)
{
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Social security number: ");
    String socialSecurity = keyboard.next();
    System.out.println();

    System.out.print("Salary: ");
    String salary = keyboard.next();
    System.out.println();

    System.out.print("Department name: ");
    String department = keyboard.next();
    System.out.println();

    // Set the data accordingly
    c.setSocialSecurity(socialSecurity);
    c.setSalary(salary);
    c.setDepartment(department);
}

}

4

4 に答える 4

1

私はあなたの Person クラスの実装を持っていないので、Person クラスを無視しました。これが私のコードです:

public class Student
{
    // declare fields that are not in Person
    private String major = "";
    private double gpa;

    // Declare accessor and mutator methods for the fields
    public String getMajor()
    {
        return major;
    }

    public void setMajor(String major)
    {
        this.major = major;
    }

    public double getGpa()
    {
        return gpa;
    }

    public void setGpa(double gpa)
    {
        this.gpa = gpa;
    }


    // Create a toString method that overrides the one in Person
    public String toString()
    {
        String str = "Grade point average: " + getGpa() +
                "...Major: " + getMajor();

        return str;
    }
    public static void main(String [] args)
    {
        Student s = new Student();
        s.setGpa(8.88);
        s.setMajor("CS");
        System.out.println(s);
    }
}

出力は次のとおりです。

成績平均点:8.88…専攻:CS

おそらく、印刷する前にオブジェクトのフィールドを設定していません。

于 2013-11-06T14:10:55.733 に答える
0

すべてのフィールドでコンストラクターを追加できます

public class Person {

    private String firstName = "";
    private String lastName = "";
    private String address = "";
    private String zipcode = "";
    private String phone = "";

    public Person(String firstName,
                  String lastName,
                  String address,
                  String zipcode,
                  String phone) {

        this. firstName = firstName;
        this.lastName = lastName;
        this.address = address;
        this.zipcose = zipcode;
        this.phone = phone;

    }
}

main

public static void main(String[] args){
    Person person = new Person(
           "John", "Smith", "444 Some Lame St", "90210", "510-555-5555");

    System.out.println(person);
}
于 2013-11-06T14:16:02.967 に答える