BufferedReader - Help!!!

[brendanmcdonagh]

Hi all,

I'm struggling with a challenge on new learnings about reading and writing from a txt file.

Now I have just learnt about the Scanner class and i can usedelimiter (",") to create tokens. But what if the txt file has a heading before each token on the first line, how do you check that what you want it to say and what it does say are true and therefore go on to next line which are where the tokens are. I do admit this is homework but i have spent a full day (which i haven't got) on one question. please somebody help me.

 /**
    * Prompts the user for the name of the text file that 
    * contains the results of the teams in this pool. The
    * method uses this file to set the results of the teams.
    */
   public void loadTeams()
   {
       OUDialog.alert("Please Select a file containing results for : " + this.getPoolName());
       String pathName = OUFileChooser.getFilename();
       File aFile = new File(pathName);
       BufferedReader bufferedFileReader = null;
       try
       {
           Scanner lineScanner;
           bufferedFileReader = new BufferedReader(new FileReader(aFile);
           String currentLine = bufferedFileReader.readLine()
           if (currentLine.equals(this.getPoolName());
           {
               currentLine = bufferedFileReader.newLine()
   }  
 
 

This is what i have managed so far but i know im wrong, my first confusion is how to get on to another line after the header is true.
The second confusion is how to end program safely if false.
This is all being done in a try catch finally statement .

the txt file reads like this

Pool A
England,3,0,1,2,0
Samoa,1,0,3,0,1
South Africa,4,0,0,3,0
Tonga,2,0,2,0,1
USA,0,0,4,0,1

Any ideas??

Brendan

[JosAH]

BufferedReaders read more behind the scenes that you can know. Why not just
read lines (using that BufferedReader)? The first line is the pool name and the
other lines are the score of the countries. A line simply is a String and it has a
nice split() method available.

Split the other lines around the comma; that method returns an array of Strings.
The first element in that array is the name of the country. The other entries
represent the scores that can be converted from a String to an int using a method
from the Integer class (check out the API for the Integer class).

You don't need a Scanner for this, most certainly not when combined with a
BufferedReader object.

kind regards,

Jos

[brendanmcdonagh]

Thanks for your advice - i was worried i would be advised to use other ways but i have to show that i have learnt what i was taught! But the textbooks are not too good at teaching!!

here's my updated code, i am a little more confident with this but I am getting a ) expected compiler error.

anyone see anything please??

Any suggestions where to put the else statement and also what to put in it to end program safely if if statement is false?

 /**
    * Prompts the user for the name of the text file that 
    * contains the results of the teams in this pool. The
    * method uses this file to set the results of the teams.
    */
   public void loadTeams()
   {
       OUDialog.alert("Please Select a file containing results for : " + this.getPoolName());
       String pathName = OUFileChooser.getFilename();
       File aFile = new File(pathName);
       BufferedReader bufferedFileReader = null;
       try
       {
           Scanner lineScanner;
           bufferedFileReader = new BufferedReader(new FileReader(aFile));
           String whichPool = bufferedFileReader.readLine();
           if(whichPool.equals(this.getPoolName())
           {
               String currentLine = bufferedFileReader.readLine();
               while(currentLine != null)
               {
 
            lineScanner = new Scanner(currentLine);
            lineScanner.useDelimiter(",");
            Team aTeam =  new Team(lineScanner.next());
            aTeam.setWon(lineScanner.next());
            aTeam.setDrawn(lineScanner.next());
            aTeam.setLost(lineScanner.next());
            aTeam.setFourOrMoreTries(lineScanner.next());
            aTeam.setSevenPointsOrLess(lineScanner.next());
            aTeam.setTotalPoints(aTeam.calculateTotalPoints());
            currentLine = bufferedFileReader.readLine();
        }
    }
}
catch(Exception anException)
{
System.out.println("Error: " + anException);
}
finally
{
try
{
bufferedFileReader.close();
}
 
catch(Exception anException)
{
System.out.println("Error: " + anException);
}           
 }          
 
   }  
 

[JosAH]

here's my updated code, i am a little more confident with this but I am getting a ) expected compiler error.

anyone see anything please??

I'm sure your compiler said some more: the line where it detected the syntax
error and a bit more descriptive message than you've told us. Please don't make
us guess but copy the error diagnostic message verbatim so that we can see
what you saw.

kind regards,

Jos

[brendanmcdonagh]

Sorry Jos

Point def taken for future.

I am using open university own compiler program.

The { under the if statement is being highlighted and ) expected is all i'm beiing told.

if
{

^ that bracket

[JosAH]

Sorry Jos

Point def taken for future.

I am using open university own compiler program.

The { under the if statement is being highlighted and ) expected is all i'm beiing told.

if
{

^ that bracket

That must've been this line then:

           if(whichPool.equals(this.getPoolName())
 

Count your left and right parentheses. The compiler saw a { where it expected
a last ), that's why it started to whine.

kind regards,

Jos

[brendanmcdonagh]

And thats why this site is the best!

[brendanmcdonagh]

Does anyone know why im getting a NULLPOINTEREXCEPTION line 3 pool A statistics at runtime with the follow code

 
/**
 * Class Pool - represents a pool in the Rugby World Cup
 * 
 * @author (M255 Course Team) 
 * @version (Version 1.0)
 */
 
import ou.*;
import java.io.*;
import java.util.*;
 
public class Pool
{
   /* instance variables */
   private String poolName; // the name of the pool
   private Team[] teams;    // the teams in the pool
   private final static int NOOFTEAMS = 5; // number of teams in each pool
 
   /**
    * Constructor for objects of class Pool
    */
   public Pool(String aName)
   {
      super();
      this.poolName = aName;
      this.teams = new Team[NOOFTEAMS];
   }
 
 
   /**
    * Returns the name of the receiver
    */
   public String getPoolName()
   {
      return this.poolName;
   }
 
 
   /**
    * Prompts the user for the name of the text file that 
    * contains the results of the teams in this pool. The
    * method uses this file to set the results of the teams.
    */
   public void loadTeams()
   {
       OUDialog.alert("Please Select a file containing results for : " + this.getPoolName());
       String pathName = OUFileChooser.getFilename();
       File aFile = new File(pathName);
       BufferedReader bufferedFileReader = null;
       try
       {
           Scanner lineScanner;
           bufferedFileReader = new BufferedReader(new FileReader(aFile));
           String whichPool = bufferedFileReader.readLine();
           if(whichPool.equals(this.getPoolName()))
           {
               String currentLine = bufferedFileReader.readLine();
               while(currentLine != null)
               {
 
            lineScanner = new Scanner(currentLine);
            lineScanner.useDelimiter(",");
            Team aTeam =  new Team(lineScanner.next());
            aTeam.setWon(lineScanner.nextInt());
            aTeam.setDrawn(lineScanner.nextInt());
            aTeam.setLost(lineScanner.nextInt());
            aTeam.setFourOrMoreTries(lineScanner.nextInt());
            aTeam.setSevenPointsOrLess(lineScanner.nextInt());
            aTeam.setTotalPoints(aTeam.calculateTotalPoints());
            currentLine = bufferedFileReader.readLine();
            System.out.println("This is a test" + aTeam.calculateTotalPoints());
        }
    }
}
catch(Exception anException)
{
System.out.println("Error: " + anException);
}
finally
{
try
{
bufferedFileReader.close();
}
 
catch(Exception anException)
{
System.out.println("Error: " + anException);
}           
 }
 
}
 
   /**
    * Returns an array containing the names of the teams in
    * this pool which will go on to the quarter-finals.
    */
   public String[] teamsToProgress()
   {
      /* to be completed by students */
      return new String[2]; //Replace in solution
   }
 
 
   /** 
    * Prints the full results for each team in this pool 
    * to the standard output.
    */
   public void displayPoolStats()
   {
      System.out.println("Statistics for "+ this.poolName);
      for(int i = 0; i < NOOFTEAMS; i++)
      {
         System.out.println(teams[i].getName() + " " 
                     + teams[i].getWon() + " "
                     + teams[i].getDrawn() + " "
                     + teams[i].getLost() + " "
                     + teams[i].getFourOrMoreTries() + " "
                     + teams[i].getSevenPointsOrLess() + " "
                     + teams[i].getTotalPoints());
     }                   
 
   }
}
 
 

I am sending the following message

Pool p = new Pool("Pool A");
p.loadTeams();
p.displayPoolStats();


I have put a system.out.println at end of while loop and everything seems fine

[blazedaces]

Every time you catch anException, also write anException.printStackTrace()

That will print out where the error is coming from. It will help to determine what exactly is the problem, because I'm sure it's not just line 3...

-blazed

[brendanmcdonagh]

Every time you catch anException, also write anException.printStackTrace()

That will print out where the error is coming from. It will help to determine what exactly is the problem, because I'm sure it's not just line 3...

-blazed

Done that blazed,

Well kind of in stead of + anExcepton i just typed something so it wasn't an exception i had written.

I think it's got something to do with the last display method, I think i ve got to put all the data into an array. might get some sleep(when it's done!!)

[blazedaces]

Done that blazed,

Well kind of in stead of + anExcepton i just typed something so it wasn't an exception i had written.

I think it's got something to do with the last display method, I think i ve got to put all the data into an array. might get some sleep(when it's done!!)

No, I mean instead of

catch(Exception anException)
{
     System.out.println("Error: " + anException);
}
 

You should write

catch(Exception anException)
{
     anException.printStackTrace();
}
 

Help us to help you.

-blazed

[JosAH]

Done that blazed,

Well kind of in stead of + anExcepton i just typed something so it wasn't an exception i had written.

I think it's got something to do with the last display method, I think i ve got to put all the data into an array. might get some sleep(when it's done!!)

Yep; in that while loop you create a Team all the time (aTeam) but you don't
do anything with it; somewhere else in your code you have a nice array of
Teams but you don't assign anything to its elements.

kind regards,

Jos