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Need Help to read .txt file and store its contents

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Join Date: Apr 2007

Posts: 5

Reputation: libran is an unknown quantity at this point

Solved Threads: 0

libran

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Newbie Poster

Need Help to read .txt file and store its contents

Oct 6th, 2007

The code on which I am working, suppose to read the contents of a file "applicants.txt" linewise and store it in a string array. Each element of array should hold one line and so on. I also want to automate the code so that when end of file is reached it should stop reading file.

Find below my code and the structure of "applicants.txt" file. Current code displays only last two lines from str array and a series of 'null' strings thereafter. I am using BlueJ environment to develop and run this code.

Kindly guide me in correct direction.

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
<span class="ad_notxt"><code class="inlinecode">
import java.util.*;
import java.io.*;
public class FranchiseManagementSystem
{
    private BufferedReader br;
    private String[] str;
 
    public FranchiseManagementSystem() throws Exception
    {
        br = new BufferedReader(new FileReader("applicants.txt"));
        str = new String[50];
        readApplicantDetails();
    }
 
    private void readApplicantDetails() throws Exception
    {
        String thisLine = "";
        int i = 0;
        while ((thisLine = br.readLine()) != null)
        {
            str[i] = thisLine;
            i++;
        }
 
        if (str.length < 5)
        {
            System.out.println("Applicant entries are less than the minimum required number.");
        }
        else
        {
            for (i=0; i<str.length; i++)
                System.out.println(str[i]);
        }
    }  
 
}
</code></span>
<span class="ad_notxt"><code class="inlinecode">
import java.util.*;
import java.io.*;
public class FranchiseManagementSystem
{
    private BufferedReader br;
    private String[] str;
    
    public FranchiseManagementSystem() throws Exception
    {
        br = new BufferedReader(new FileReader("applicants.txt"));
        str = new String[50];
        readApplicantDetails();
    }
    
    private void readApplicantDetails() throws Exception
    {
        String thisLine = "";
        int i = 0;
        while ((thisLine = br.readLine()) != null)
        {
            str[i] = thisLine;
            i++;
        }
        
        if (str.length < 5)
        {
            System.out.println("Applicant entries are less than the minimum required number.");
        }
        else
        {
            for (i=0; i<str.length; i++)
                System.out.println(str[i]);
        }
    }  
    
}
</code></span>

Structure of "applicants.txt" file

Cynthia Powell 99031911 F 17 18000 Y
Peter Best 99051234 M 32 70000 N
Andrew White 99042367 M 25 20000 Y
Jane Asher 99075235 F 29 5000 Y
Malcom Evans 98763476 M 18 15000 Y

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Join Date: Dec 2006

Posts: 192

Reputation: nschessnerd is an unknown quantity at this point

Solved Threads: 8

nschessnerd nschessnerd is offline

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Junior Poster

Re: Need Help to read .txt file and store its contents

Oct 7th, 2007

So... you've got a few problems with your code... one really really bad thing is that you make each method throw an exception. that means you will never see if there are any errors. You were getting a bunch of nulls because you were storing values in an array of 50 and printing out each spot...
here is the fixed code. I left it as close to normal as possible

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
import java.util.*;
import java.io.*;
public class FranchiseManagementSystem
{
    private BufferedReader br;
    private String[] str;
 
    public FranchiseManagementSystem() throws Exception
    {
        br = new BufferedReader(new FileReader("applicants.txt"));
                str = new String[50];
        readApplicantDetails();
    }
 
    private void readApplicantDetails() throws Exception
    {     
            String thisLine = br.readLine();
        int i = 0;
              while (thisLine != null)
        {           
               str[i] = thisLine;
              thisLine = br.readLine();
            i++;
        }
        if (i < 5)
        {
            System.out.println("Applicant entries are less than the minimum required number.");
        }
        else
        {
          for (int a=0; a<i; a++)
              System.out.println(str[a]);
                  }
    }  
 
}
import java.util.*;
import java.io.*;
public class FranchiseManagementSystem
{
    private BufferedReader br;
    private String[] str;
    
    public FranchiseManagementSystem() throws Exception
    {
        br = new BufferedReader(new FileReader("applicants.txt"));
                str = new String[50];
        readApplicantDetails();
    }
    
    private void readApplicantDetails() throws Exception
    {     
            String thisLine = br.readLine();
        int i = 0;
              while (thisLine != null)
        {           
               str[i] = thisLine;
              thisLine = br.readLine();
            i++;
        }
        if (i < 5)
        {
            System.out.println("Applicant entries are less than the minimum required number.");
        }
        else
        {
          for (int a=0; a<i; a++)
              System.out.println(str[a]);
                  }
    }  
    
}

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Join Date: Aug 2007

Posts: 771

Reputation: darkagn has a spectacular aura about

Solved Threads: 104

darkagn

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Master Poster

Re: Need Help to read .txt file and store its contents

Oct 7th, 2007

Hi Libran,

To help debug your code, try adding some println statements to gain a better understanding of what is going on. Please see my comments below.

Help with Code Tags

(Toggle Plain Text)


import java.util.*;
import java.io.*;
public class FranchiseManagementSystem
{
    private BufferedReader br;
    private String[] str;
    
    public FranchiseManagementSystem() throws Exception
    {
        br = new BufferedReader(new FileReader("applicants.txt"));
        str = new String[50];
        readApplicantDetails();
    }
    
    private void readApplicantDetails() throws Exception
    {
        String thisLine = "";
        int i = 0;
        while ((thisLine = br.readLine()) != null)
        {
            System.out.println(thisLine);
            System.out.println(i);
            str[i] = thisLine;
            System.out.println(str[i]);
            i++;
        }

        if (str.length < 5)
        {
            System.out.println("str.length < 5");
            // str.length must be at least 5 since the following println statement fails to execute
            System.out.println("Applicant entries are less than the minimum required number.");
        }
        else
        {
            for (i=0; i<str.length; i++)
                System.out.println(str[i]);
        }
    }  
    
}

Hopefully these println statements will help you debug your program. Don't forget to comment them all out for your final program!