Add method not adding Student in RandomAccessFile
https://stackoverflow.com/questions/11903004
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25-06-2021 - |
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Hey my randomAccessFile application is not adding the student to the file. I have set up a student store using an arrayList and the added student is being added to the store but it is not being displayed in the file "ContactDetails.txt". Can anyone see what is wrong?
Here is my code: 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;
}
//---------------------------------------------------------------------------------------
}
Student
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";
}
}
Solution
please post Student class code whether you override the toString() method in Student class
I have test you code, if I input 1, it will print all student information which you have input in you main method. But if I input 2, after input the Student information, you code just add the information in Arraylist in memory, not output it to the file. So then I input 1, it will not output the new Student information which I have input before.
I think you may need output new Student information to file.
edit
case 2:
System.out.println("Add");
Student student = MenuMethods.userInput();
details.add(student);
break;
to
case 2:
System.out.println("Add");
Student student = MenuMethods.userInput();
details.add(student);
file.write(student.toString().getBytes());
break;
and more you have just read first 30 line of the file in you read All method change
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);
}
to
public void readAll(RandomAccessFile file) throws IOException
{
file.seek(0);
String code;
while((code=file.readLine())!=null)
System.out.println(code);
}
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