Sorting and Searching String (Please help me)

Question

Hi, Could somn please be of any help here. I am trying to sort this string in alphabetical order and then search for data available but I am not makingprogress with the code. Does anyone have any advise or better still the code to solve this problem... This is hat I have at the moment
import java.util.*;
import java.io.PrintStream;
import java.io.File;
import java.io.FileNotFoundException;
public class coursework2
     public static final int MAX_RECORDS = 20;
     public static String lastName[] = new String[MAX_RECORDS];
     public static String firstName[] = new String[MAX_RECORDS];
     public static String telNumber[] = new String[MAX_RECORDS];
     public static String emailAddress[] = new String[MAX_RECORDS];
     public static int read_in_file(String file_name)
          Scanner read_in;
          Scanner line;
          int record_count = 0;
          String record;
          try
               read_in = new Scanner(new File(file_name));
               // read in one line at a time
               read_in.useDelimiter(System.getProperty("line.separator"));
               while (read_in.hasNext())
                    // Test to see if there are too many records in the file
                    if (record_count == MAX_RECORDS)
                         System.out.printf("Only %d records allowed in file", MAX_RECORDS);
                         System.exit(0);
                    // read in record
                    record = new String(read_in.next());
                    // Split the record up into its fields and store in
                    // appropriate arrays
                    line = new Scanner(record);
                    line.useDelimiter("\\s*,,\\s*");
                    lastName[record_count] = line.next();
                    firstName[record_count] = line.next();
                    telNumber[record_count] = line.next();
                    emailAddress[record_count] = line.next();
                    // Increment record count
                    record_count++;
          catch (FileNotFoundException e)
               e.printStackTrace();
          return record_count;
     public static void write_out_file(int no_of_records, String filename)
          PrintStream write_out;
          int counter;
          try
               // Create new file
               write_out = new PrintStream(new File(filename));
               // Output all reacords
               for(counter = 0; counter < no_of_records; counter++)
                    // Output a record
                    write_out.print(lastName[counter]);
                    write_out.print(",,");
                    write_out.print(firstName[counter]);
                    write_out.print(",,");
                    write_out.print(telNumber[counter]);
                    write_out.print(",,");
                    write_out.println(emailAddress[counter]);
               // Close file
               write_out.close();
          catch (FileNotFoundException e)
               e.printStackTrace();
     // Your 'functions' go here
     //This code sorts out the record after loaded into alphabetical order using
     //the selection sort method
     public static void sort()
     // Your 'main' code goes here
     //The code below uses a binary search method to search for record because
     //record have been sorted and this would make search faster and more efficient
     public static boolean linearSearch(String strFirstName, String strLastName)
          //Set-up data_input and declare variables
          //This linear search searches for record in the contact application.
          //Search for a record using surname only
               int i = 0;
               boolean found = false;
               while (!found && i < lastName.length)
                    if(strFirstName.equals("") && strLastName.equals(""))
                         return true;
                    if(lastName.equalsIgnoreCase(strLastName)){
               //List records from surname only
               System.out.println("Enter your search criteria (last name only):");
                    System.out.print(lastName[i] +     "\t" + firstName[i] + "\t" + telNumber[i] +"\t" + emailAddress[i]);
                    System.out.println("");
                    if (lastName[i].compareTo(strLastName) == 0)
                         //Compare the last name values and type to make sure they are same.
                         found = true;
                              i++;
                              System.out.print(lastName[i] +     "\t" + firstName[i] + "\t" + telNumber[i] +"\t" + emailAddress[i]);
                                   System.out.println("");
                         return found;
          //Search for a record using first name only
     public static void main(String[] args)
          // Set-up data input
          Scanner data_input = new Scanner(System.in);
          // Declare Variables
          int number_of_records;
          String filename;
          int counter;
          // Get filename and read in file
          System.out.print("Enter the masterfile file name: ");
          filename = data_input.next();
          number_of_records = read_in_file("data2.dat");
          //Get new filename and write out the file
          System.out.print("Enter new masterfile file name: ");
          filename = data_input.next();
          //System.out.println("Enter your search criteria (first or last name):");
          linearSearch("*", "");
Am very sorry this is long, the file should be sorted after it is loaded and I have that, You can make up some data with last ane, first name, tel and email to show me an example. Thanks alot
Joseph

Answer 1

Hi Monica, Thanks for you patience with me.
I have tried writing a selection sort method but am having some errors. Could you kindly have a lookand correct me please.
This is the code i wrote
public static void selectionSort(Comparable [] data)
          String strFirstName;
          String strLastName;
          Comparable temp;
          for(int i = 0; i < lastName.length; i++)
               lastName = index;
               for (int j = i; j < lastName.length; j++)
                    if (lastName[j].compareTo(lastName) < 0)
                         lastName[j] = lastName[i];
               //Swap the string values
               temp = lastName[j];
               lastName[j] = lastName[i];
               lastName[i] = temp;
As you requested, below are 4 error messages I had
E:\coursework2.java:101: cannot find symbol
symbol : variable index
location: class coursework2
               lastName = index;
^
E:\coursework2.java:107: cannot find symbol
symbol : variable j
location: class coursework2
               temp = lastName[j];
^
E:\coursework2.java:108: cannot find symbol
symbol : variable j
location: class coursework2
               lastName[j] = lastName[i];
^
E:\coursework2.java:109: incompatible types
found : java.lang.Comparable
required: java.lang.String
               lastName[i] = temp;
^
4 errors
JCompiler done.
JCompiler ready.
Joseph