search method help

[djtosh]

hi there hoping someone can help me out with this.

im designing a code that is a basic database holding peoples details and i need to implement a method that searches by txt for a record by their last name.

import java.util.*;
import java.io.PrintStream;
import java.io.File;
import java.io.FileNotFoundException;
 
public class coursework4
{
    private static final int MAX_RECORDS = 20;
    private static String lastName[] = new String[MAX_RECORDS];
    private static String firstName[] = new String[MAX_RECORDS];
    private static String telNumber[] = new String[MAX_RECORDS];
    private static String emailAddress[] = new String[MAX_RECORDS];
    private static Scanner data_input = new Scanner(System.in);
 
    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();
        }
    }

this is the code i have for reading the data in. i dont know how i can go about coding a search method. hopefully someone can help me thanks.

[JosAH]

hi there hoping someone can help me out with this.

im designing a code that is a basic database holding peoples details and i need to implement a method that searches by txt for a record by their last name.

import java.util.*;
    private static String lastName[] = new String[MAX_RECORDS];
    private static String firstName[] = new String[MAX_RECORDS];
    private static String telNumber[] = new String[MAX_RECORDS];
    private static String emailAddress[] = new String[MAX_RECORDS];
 

This is the Fortran way of doing things because in that language you can't do
any better than that. Think objects:

public class Contact {
   private String lastName;
   private String firstName;
   private String telNumber;
   private String emailAddress;
   //
   // ctor:
   public Contact(String lastName, String firstName, 
                  String telNumber, String emailAddress) {
      this.lastName= lastName;
      this.firstName= firstName;
      this.telNumber= telNumber;
      this.emailAddress= emailAddress;
   }
   // getters and setters here ...
}

and then use a List<Contact> for your in-core database.

kind regards,

Jos
}

[djtosh]

hi there thanks for replying but i cant see how that helps me, i need to know how to code a search method that will start with getting text from the user and then look in to the lastName array and see which records have the text in it.

static int find(int[] A, int N) {
// Searches the array A for the integer N.

for (int index = 0; index < A.length; index++)
{
if ( A[index] == N )
return index; // N has been found at this index!
}

something similar to these i think but applying to my code, i cnt work out what goes where

[r035198x]

hi there thanks for replying but i cant see how that helps me, i need to know how to code a search method that will start with getting text from the user and then look in to the lastName array and see which records have the text in it.



something similar to these i think but applying to my code, i cnt work out what goes where

Just use a loop and compare each element in the array with the entered text.
BTW Why are you using Java if you're not willing to think objects in your program?

[djtosh]

Just use a loop and compare each element in the array with the entered text.

can you explain this in code please

[r035198x]

can you explain this in code please

Why don't you write the code first and we'll see if you need more help on it.

BTW:You should really consider using objects.

[djtosh]

if i knew how to write the code i wouldnt be asking for it

public static void textsearch(Stri ng[] args)
{
Scanner data_input = new Scanner(System. in);
// Get user's name
System.out.prin t("Please enter search parameters: ");
String t = data_input.next ();

static int find(int[] lastName, int t)
{


for (int index = 0; index < lastName.length ; index++)
if ( lastName[index] == t )
return index;
}


}

this is what i tried before i came on here and it doesnt work

[r035198x]

if i knew how to write the code i wouldnt be asking for it



this is what i tried before i came on here and it doesnt work

Do not use == to compare two Strings. Use the .equals method.

[djtosh]

changed it from == t to .equals(t) but it still doesnt output the record

[r035198x]

changed it from == t to .equals(t) but it still doesnt output the record

Wait a minute. There's something going on here.
You have an int[] not a String[]? So you couldn't have out the .equals method correctly in there. Are you comparing strings only or a string to an int.

BTW:Again I have to point out the need to write object oriented code if you have decided to use Java.