添加方法不在RandomAccessFile中添加Student

时间:2012-08-10 13:45:18

标签: java arraylist add random-access

嘿,我的randomAccessFile应用程序没有将学生添加到文件中。我已经使用arrayList设置了一个学生商店,并且添加的学生正被添加到商店,但它没有显示在文件“ContactDetails.txt”中。任何人都可以看到有什么问题吗?

这是我的代码: MainApp

import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.Scanner;



public class MainApp
{
//---------------------------------------------------------------------------------------
//  The Scanner is declared here for use throughout the whole MainApp.
//---------------------------------------------------------------------------------------
    private static Scanner keyboard = new Scanner(System.in);

    public static void main(String[] args) throws Exception 
    {
        new MainApp().start();

    }
    public void start()throws Exception 
    {
        StudentStore details = new StudentStore();
        Student a = new Student("Becky O'Brien", "DKIT26", "0876126944", "bexo@hotmail.com");
        Student b = new Student("Fabio Borini", "DKIT28", "0876136944", "fabioborini@gmail.com");
        Student c = new Student("Gaston Ramirez", "DKIT29", "0419834501", "gramirez@webmail.com");
        Student d = new Student("Luis Suarez", "DKIT7", "0868989878", "luissuarez@yahoo.com");
        Student e = new Student("Andy Carroll", "DKIT9", "0853456788", "carroll123@hotmail.com");
        details.add(a);
        details.add(b);
        details.add(c);
        details.add(d);
        details.add(e);
        //details.print();


        RandomAccessFile file = new RandomAccessFile("ContactDetails.txt","rw");
        //getBytes() returns an array of bytes.
        //Because i have put the store in a static Array.(I done this because i could find no other
        //Simple way to write a Student Object.)
        //None of the methods of the RandomAccessFile write class worked with this.
        //Student[] students = {a,b,c,d,e};
        details.write(file);
        //details.readAll(file);
        int choice;
        System.out.println("Welcome to the Company Database.");
        do 
        {
            choice = MenuMethods.getMenuChoice( "1.\tView" +
                                                "\n2.\tAdd"+ 
                                                "\n3.\tDelete" + 
                                                "\n4.\tDelete All " + 
                                                "\n5.\tEdit"+ 
                                                "\n6.\tSearch" + 
                                                "\n7.\tStore" + 
                                                "\n8.\tExit", 8,
                                                "Please enter your choice:", "Error [1,8] Only");
        // String temp = keyboard.nextLine(); This prevented entering the choice.
        //---------------------------------------------------------------------------------------
//          Name:        Switch Statement.
//          Description: This is used for a menu system.
        //---------------------------------------------------------------------------------------
                    switch (choice) 
                    {
        //---------------------------------------------------------------------------------------
//          Name:        Case 1: View All
//          Description: Choice 1 is to view all employee's in the store.
        //---------------------------------------------------------------------------------------
                    case 1:
                        System.out.println("View All");
                        details.readAll(file);
                        break;
        //---------------------------------------------------------------------------------------
//          Name:        Case 2: Add
//          Description: Choice 2 is to add an employee to the store.
        //---------------------------------------------------------------------------------------
                    case 2:
                        System.out.println("Add");
                        Student student = MenuMethods.userInput();
                        details.add(student);
                        break;
        //---------------------------------------------------------------------------------------
//          Name:        Case 3: Delete by Name.
//          Description: Choice 3 gives the user an option to delete an employee by name.
        //---------------------------------------------------------------------------------------
                    case 3:
                        System.out.println("Delete by Name.");
                        //Employee employeeDelete = MenuMethods.userInputByName();
                        //Store.searchByName(employeeDelete.getEmployeeName());
                        //Store.remove(employeeDelete.getEmployeeName());
                        break;
        //---------------------------------------------------------------------------------------
//                      Name:        Case 4: Delete All.
//                      Description: Choice 4 gives the user a choice to delete all employee's in the store.
        //---------------------------------------------------------------------------------------
                    case 4:
                        System.out.println("Delete All.");
                        //Store.clear();

                        break;
        //---------------------------------------------------------------------------------------
//                      Name:        Case 4: Edit.
//                      Description: Choice 4 gives the user an option to edit the employee's in the store.
//                                   This consists of changing the employee's name,id and e-mail address.
        //---------------------------------------------------------------------------------------
                    case 5:
                        System.out.println("Edit");

                        break;

        //---------------------------------------------------------------------------------------
//          Name:        Case 6: Search.
//          Description: Choice 6 gives the user 2 options: Search by name and Search by email.
//                       Search will run through the store and output the employee match the user inputs.
        //---------------------------------------------------------------------------------------
                    case 6:

                        break;
        //---------------------------------------------------------------------------------------
//          Name:        Case 7: Store.
//          Description: Choice 7 gives the user an option to copy and read a store
//                       using read and write class from Java.
        //---------------------------------------------------------------------------------------
                    case 7:


                        break;
        //---------------------------------------------------------------------------------------
//          Name:        Case 8: Exit.
//          Description: Choice 8 will exit the application.
        //---------------------------------------------------------------------------------------
                    case 8:
                        System.out.println("Exit");

                        break;
                    }

                } while (choice != 8);



        file.close();
    }


 }

StudentStore

//---------------------------------------------------------------------------
//Imports.
//---------------------------------------------------------------------------   
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.List;
//---------------------------------------------------------------------------   

public class StudentStore
{
//---------------------------------------------------------------------------
//ArrayList declaration.
//---------------------------------------------------------------------------
    List<Student> students = new ArrayList<Student>();
//---------------------------------------------------------------------------
//Name:          Add method.
//Description:   Adds a student to the ArrayList.
//---------------------------------------------------------------------------
    public void add(Student student) 
    {
        students.add(student);
    }
//---------------------------------------------------------------------------
//Name:          DeleteAll method.
//Description:   Delete's everything in the ArrayList.
    //---------------------------------------------------------------------------
     public void deleteAll()
     {
           students.clear();
     }
//---------------------------------------------------------------------------
//Name:          Print method.
//Description:   Prints out the contents of the ArrayList.
//---------------------------------------------------------------------------
    public void print() 
    {
        for (int i = 0; i < students.size(); i++) 
        {
          Student a = students.get(i);
            System.out.println(a.toString());
        }
    }
    public int size()
    {
        return (students == null) ? 0 : students.size();
    }
    public void write(RandomAccessFile file) throws IOException
    {
        for (Student s: students)
        {
            byte[] bytes = s.toString().getBytes();
            for(byte byteWrite : bytes)
            {
                file.writeByte(byteWrite);
            }
        }

    }

    public void readAll(RandomAccessFile file) throws IOException
    {
        final int Record_Length = 30;
        int recordNumber = 0;
        file.seek((recordNumber) * Record_Length);

        String code ="";
        for(int i = 0; i < 30; i++)
        {
        code += file.readLine() + "\n";
        }
        System.out.println(code);
    }

}

MenuMethods

//---------------------------------------------------------------------------------------
//  Name:           Imports. 
//  Description:    To allow the use of different Java classes.
//---------------------------------------------------------------------------------------
import java.util.Scanner;
//---------------------------------------------------------------------------------------

public class MenuMethods 
{
    private static Scanner keyboard = new Scanner(System.in);
//---------------------------------------------------------------------------------------
//  Methods for the Company Application menu.
//---------------------------------------------------------------------------------------

//---------------------------------------------------------------------------------------
//  Name:           getMenuChoice.
//  Description:    Method for validating the choice.
//---------------------------------------------------------------------------------------
    public static int getMenuChoice(String menuString, int limit,String prompt, String errorMessage) 
    {
        System.out.println(menuString);
        int choice = inputAndValidateInt(1, limit, prompt, errorMessage);
        return choice;
    }

//---------------------------------------------------------------------------------------
//  Name:        inputAndValidateInt.
//  Description: This method is used in the getMenuChoice method.
//---------------------------------------------------------------------------------------
    public static int inputAndValidateInt(int min, int max, String prompt,String errorMessage) 
    {
        int number;
        boolean valid;
        do 
        {
            System.out.print(prompt);
            number = keyboard.nextInt();
            valid = number <= max && number >= min;
            if (!valid) 
            {
                System.out.println(errorMessage);
            }
        } while (!valid);
        return number;
    }

//---------------------------------------------------------------------------------------
//  Name:        userInput
//  Description: This method is used in the MainApp to give the user capability to enter
//               the details when adding details of an employee into the store.
//---------------------------------------------------------------------------------------
    public static Student userInput() 
    {
        String temp = keyboard.nextLine();
        Student s = null;
        System.out.println("Please enter the Student Name:");
        String studentName = keyboard.nextLine();
        System.out.println("Please enter the Student ID:");
        String studentId = keyboard.nextLine();
        System.out.println("Please enter the Student E-mail address:");
        String studentEmail = keyboard.nextLine();
        System.out.println("Please enter the Student telephone number:");
        String studentTelephoneNumber = keyboard.nextLine();
        return s = new Student(studentName, studentId, studentEmail,studentTelephoneNumber);

    }

//---------------------------------------------------------------------------------------
//  Name:        userInputByName.
//  Description: This method is used in the MainApp to give the user capability to search by name.
//---------------------------------------------------------------------------------------
    public static Student userInputByName() 
    {
        // String temp is for some reason needed. If it is not included
        // The code will not execute properly.
        String temp = keyboard.nextLine();
        Student s = null;
        System.out.println("Please enter the Student Name:");
        String studentName = keyboard.nextLine();

        return s = new Student(studentName);

    }

//---------------------------------------------------------------------------------------
//  Name:        userInputByEmail
//  Description: This method is used in the MainApp to give the user capability to search by email.
//---------------------------------------------------------------------------------------
    public static String userInputByEmail() 
    {
        // String temp is for some reason needed. If it is not included
        // The code will not execute properly.
        String temp = keyboard.nextLine();
        Student s = null;
        System.out.println("Please enter the StudentEmail:");
        String studentEmail = keyboard.nextLine();
        // This can use the employeeName's constructor because java accepts the
        // parameters instead
        // of the name's.
        return studentEmail;

    }
//---------------------------------------------------------------------------------------
}

学生

import java.io.Serializable;

public class Student implements Serializable
{
//---------------------------------------------------------------------------
//  Class Variables.
//---------------------------------------------------------------------------   
    private String studentName;
    private String studentId;
    private String studentTelephoneNumber;
    private String studentEmail;
//---------------------------------------------------------------------------
//  Constructor.
//---------------------------------------------------------------------------   
    public Student(String studentName, String studentId,String studentTelephoneNumber, String studentEmail) 
    {
        this.studentName = studentName;
        this.studentId = studentId;
        this.studentTelephoneNumber = studentTelephoneNumber;
        this.studentEmail = studentEmail;
    }
//---------------------------------------------------------------------------------------
//  Overloading the constructor for the use with userInputByName method.
//---------------------------------------------------------------------------------------
    public Student(String studentName) 
    {
        this.studentName = studentName;
    }
//---------------------------------------------------------------------------
//  Getters.
//---------------------------------------------------------------------------
    public String getStudentName()
    {
        return studentName;
    }
    public String getStudentId() 
    {
        return studentId;
    }
    public String getStudentTelephoneNumber() 
    {
        return studentTelephoneNumber;
    }
    public String getStudentEmail() 
    {
        return studentEmail;
    }
//---------------------------------------------------------------------------
//  Setters.
//---------------------------------------------------------------------------
    public void setStudentName(String studentName) 
    {
        this.studentName = studentName;
    }
    public void setStudentId(String studentId) 
    {
        this.studentId = studentId;
    }
    public void setStudentTelephoneNumber(String studentTelephoneNumber) 
    {
        this.studentTelephoneNumber = studentTelephoneNumber;
    }
    public void setStudentEmail(String studentEmail) 
    {
        this.studentEmail = studentEmail;
    }
//---------------------------------------------------------------------------
//  toString.
//---------------------------------------------------------------------------
    public String toString() 
    {
        return "---------------------------Student--------------------------- " +
                "\nStudent Name:" + studentName + 
                "\nStudent Id:"+ studentId + 
                "\nStudent Telephone Number:"+ studentTelephoneNumber + 
                "\nStudent Email:" + studentEmail +"\n\n";
    }


}

1 个答案:

答案 0 :(得分:1)

请发送学生班级代码 是否覆盖Student类

中的toString()方法

我测试了你的代码,如果输入1,它将打印你在main方法中输入的所有学生信息。 但是如果我输入2,在输入学生信息之后,您只需将代码添加到内存中的Arraylist中,而不是将其输出到文件中。所以我输入1,它不会输出我之前输入的新学生信息。

我认为您可能需要输出新的学生信息才能存档。

修改

case 2:
                        System.out.println("Add");
                        Student student = MenuMethods.userInput();
                        details.add(student);
                        break;

case 2:
                        System.out.println("Add");
                        Student student = MenuMethods.userInput();
                        details.add(student);
file.write(student.toString().getBytes());
                    break;

以及更多你刚读完文件的前30行所有方法 变化

public void readAll(RandomAccessFile file) throws IOException
    {
        final int Record_Length = 30;
        int recordNumber = 0;
        file.seek((recordNumber) * Record_Length);

        String code ="";
        for(int i = 0; i < 30; i++)
        {
        code += file.readLine() + "\n";
        }
        System.out.println(code);
    }

public void readAll(RandomAccessFile file) throws IOException
    {
        file.seek(0);

        String code;
while((code=file.readLine())!=null)
        System.out.println(code);
    }