fileReader

[kelvin cheung]

i want to make a program that can count the :
[YEAR] and the [Celsius Degree] of that year.
it will have to find those information on a .txt file which look something like :
1871
3.1
1872
4.8
1873
4.7
1874
4.3
it will also have to find the MAX, Avarage and the MIN temp.
and also have to count how many it is registered.
------------------------------------------------------
i wonder how to write the program that knows that the first 1 is a YEAR,
And the second is a DEGREE? and then count them as one! ??

[Elouise Kivineva]

You read the file as a String, then tokenize it. Every odd token (the 1st, 3rd, 5th, ...) is a year and every even token (2nd, 4th, ...) is a temperature - until you run out of tokens.
You might want to read up on the String & StringTokenizer classes in the Java API.

[kelvin cheung]

hi Elouise,
how do i count odd and even tokens?

[Stan James]

I think with your year & date information on separate lines you can use readLine() instead of tokenizing. Take a look at the doc on BufferedReader and readLine().
Start sketching out the highest level logic of your program. Maybe:

open input
while more year & temperature pairs
   read a year line
   read a temperature line
   turn temp string into temp number of some kind
   see if this is a new min
   see if this is a new max
   count this year for average calculation
   add this temperature for average calculation
end while
close input
display max year & temp
display min year & temp
calculate & display average

Ooops, I hope I haven't done more of your homework than I should. Does that give you some ideas? For fun, maybe see if you can write a Java method with exactly those lines turned into code.

[Elouise Kivineva]

How do you count even and odd tokens?
It's not really counting, but for instance you could read using a loop that reads first the year, then the temperature. On the next round it reads first the year, then the temp. Etc., etc., as long as there are tokens (or token pairs) to read.

[kelvin cheung]

thanks for the replies.
but i got some problems with the fileReading :

 FileReader leseforbindelse = new FileReader(filnavn); // forbindelse
        BufferedReader fil = new BufferedReader(leseforbindelse); // format
        
        String enLinje = fil.readLine();
        while (enLinje != null)
        {
            StringTokenizer tekst = new StringTokenizer(enLinje);
            String tekst2 = tekst.nextToken();
            System.out.println(tekst2);
        }
        fil.close(); 

it only prints "1871" out, over and over again.... why ?

[Alex McCormick]

I'm taking a bit of a wild stab here as I haven't done file reading in a while, but don't you have to include your readLine() in the loop? Otherwise I think it doesn't know to read the next line, which is why it keeps printing 1871 over and over.

[kelvin cheung]

thank you alex ..it worked
like this

 String enLinje = fil.readLine();
        while (enLinje != null)
        {
            StringTokenizer tekst = new StringTokenizer(enLinje);
            String tekst2 = tekst.nextToken();
            System.out.println(tekst2);
            enLinje = fil.readLine();
        }
        fil.close(); 

[kelvin cheung]

ok...i have tried but,...
i still dont know how to distinguish the years and the temps,
and pair them as 1.
any ideas?

[Elouise Kivineva]

        // read a line
        String enLinje = fil.readLine();
        // 1st ia a year
        String year = enLinje ;
        // read a line
        enLinje = fil.readLine();
        // 2nd is a temp
        String temp = enLinje ;
        int howManySets = 1 ;
        int min = Integer.parseInt( temp ) ;
        int max = min ;
        int tempSum = min ; 
        
        // all other sets read in the loop
        // assumes there are always sets
        // you may want to add error checking
        int latestTemp = 0 ; 
        // read a line
        enLinje = fil.readLine();       
        while ( enLinje != null ) 
        {   
            // 1st ia a year
            year = enLinje ;
            System.out.println( "year: " + year );
            // read a line
            enLinje = fil.readLine(); 
            // 2nd is a temp          
            temp = enLinje ;  
            System.out.println( "temp: " + temp ); 
            
            latestTemp = Integer.parseInt( temp ) ;
            if ( latestTemp < min )
               // you figure it out
            if ( latestTemp > max )
               // you figure it out
            tempSum = // you figure it out ;
            howManySets = // you figure it out ;
            // read a line
            enLinje = fil.readLine(); 
        }        
        fil.close(); 

[kelvin cheung]

thank you Elouise Kivineva
for taking your time to tell me how to do.
i finally did it ..
my next thing to do is to make a GUI version of this.
i will try myself. if i find some difficulties, i will ask you guys.
take care