линейное хеширование или зондирование ошибок с кодом

Question

Я застрял с этим кодом, я получаю много ошибок, какое-то время пытался их исправить, я думаю, что это незначительные ошибки, но я все еще не могу их понять. Количество записей, которые я ' м используется 50 студентов, и номера студентов будут ключевыми записями. Структура записи: целое число. Строка имени. Адресная строка. Код: Спасибо.

 // first create a container class to hold structure of Student record
public class StudentRecord {
    int StudentNumber;
    String StudentName;
    String StudentAddress;
    // initializer or constructor
    public StudentRecord(id, name, address) {
        StudentNumber = id;
        StudentName = name;
        StudentAddress = address;
    }
}
/* now a class that holds file manipulation methods to add,search,delete records with a file using hashing technique */
import java.util.*;
import java.io.*;
public class SimpleSerializedIO {
    /* method to add record to file()->creates hash table->load a student record to hash table
      ->opens/creates file object->inserts/Save record->closes file stream */
    private static void SaveRecord() {
        System.out.println("|nsert,Save Method |");
        e
        System.out.println();
        Hashtable < String, Object > h = new Hashtable < String, Object > ();
        // create student record with roll no,name and address
        // roll number of Student is assumed unique key here which is hashed on put() call o insert
        h.put("38", new StudentRecord(38, "StudentName1", "StudentAddress1"));
        try {
            System.out.println("Creating File/Object output stream...");
            FileOutputStream fileOut = new FileOutputStream("StudentRecords.txt"); // provide actual full path
            ObjectOutputStream out = new ObjectOutputStream(fileOut);
            System.out.println("Inserting/Saving Hashtable Object...");
            out.writeObject(h);
            System.out.println("Closing all output streams after nsert/Save operation...\n");
            out.close();
            fileOut.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /* read records and search method()->open Student record file->load all records into an empty hash table
     ->close file->query hash table by key input and print search data */
    private static void ReadAllRecordsAndSearch(String studentNumber) {
        System.out.println("| Search Method |");
        System.out.println();
        Hashtable h = null;
        try {
            System.out.println("Creating File/Object input stream...");
            FileInputStream fileIn = new FileInputStream("StudentRecords.txt"); // provide actual full path
            ObjectInputStream in = new ObjectInputStream(fileIn);
            System.out.println("Loading Hashtable Object...");
            h = (Hashtable) in .readObject();
            System.out.println("Closing all input streams...\n"); in .close();
            fileIn.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("Printing out Searched element...");
        // this loop is just for illustration.You can avoid it and directly query or search the hash table when key is passed.
        for (Enumeration e = h.keys(); e.hasMoreElements();) {
            Object obj = e.nextElement();
            // check if key in context reached?here key is StudentNumber
            if (h.get(studentNumber).StudentNumber.toString() == studentNumber) {
                System.out.println(" - Element(" + obj + ") = " + h.get(obj));
            }
        }
        System.out.println();
    }
    /* delete a record after loading all from file into hash table */
    public void DeleteRecord(String studentNumber) {
        // /////////////////////
        System.out.println("| Delete Method |");
        System.out.println();
        Hashtable h = null;
        try {
            System.out.println("Creating File/Object input stream...");
            FileInputStream fileIn = new FileInputStream("StudentRecords.txt"); // provide actual full path
            ObjectInputStream in = new ObjectInputStream(fileIn);
            System.out.println("Loading Hashtable Object...");
            h = (Hashtable) in .readObject();
            System.out.println("Closing all input streams...\n"); in .close();
            fileIn.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("Printing out deleted element...");
        // this loop is just for illustration.You can avoid it and directly query to delete from hash table when key is passed.
        for (Enumeration e = h.keys(); e.hasMoreElements();) {
            Object obj = e.nextElement();
            // check if key in context reached?here key is StudentNumber
            if (h.get(studentNumber).StudentNumber.toString() == studentNumber) {
                System.out.println(" - Deleting Element(" + obj + ") = " + h.get(obj));
                h.remove(studentNumber);
            }
        }
        System.out.println();
        // ////////////////////
    }
    // driver code to test and demo
    public static void main(String[] args) {
        SaveRecord();
        ReadAllRecordsAndSearch("38");
        DeleteRecord("38");
    }
}