How to Read data from text file and calculate the values?

[Eranga]

janeansley, it's better that you familiar with basis error message handling in Java. All what you get in the code are simple ones.

[janeansley]

Code:

import java.io.*;

public class Testing
{
   public static void main( String args[] )
   throws java.io.IOException
   {

	   final int PCOUNT = 5000;
	   int a[]= new int[PCOUNT];
	   int i = 0;
	   int j = 0;
	   double y[];

	   String filename, inLine;


	   //keyboard input stream
	   InputStreamReader isr = new InputStreamReader(System.in);
	   BufferedReader br = new BufferedReader(isr);

	   //get the input data
	   System.out.print( "Enter the txt file name(full path): " );
	   filename = br.readLine();

	   //file input stream
	   BufferedReader fi = new BufferedReader(new FileReader(filename));

	   //read existing data and calculate
           while((inLine = fi.readLine()) != null) {
               a[i] = Integer.parseInt(inLine);
               y[j] = ((4.2*a[i]/1010)-1.35);
               i++;
           }
          fi.close();

          try{
		  FileWriter fw = new FileWriter("C:\\output.txt");
		  BufferedWriter out = new BufferedWriter(fw);
		  String Temp = null;
		  	   for(j=0; j<= i; j++){
				   Temp += y[j] + "\n";}
		  out.write(Temp.substring(4));
		  out.close();
                        }catch (Exception A){}

   }

}

After corected and compiled, another errors come again.

Quote:

Testing.java:32: variable y might not have been initialized
y[j] = ((4.2*a[i]/1010)-1.35);
^
Testing.java:42: variable y might not have been initialized
Temp += y[j] + "\n";}
^
2 errors

Why it said variable y might not have been initialized? I might did something wrong there. I am not sure whether my array has been declared properly. Please correct me thanks.

[Fubarable]

It seems to me that your method of programming is:

1) find an error and post it here.
2) fix what is stated here, then go back to step one.

I think that somewhere in this loop you have to have:

3) try to debug it myself.

Don't you think?

[Eranga]

Even get advice 100 times why these guys don't listen that. Try yourself at least a simple error like this. Error says that 'y' is not initialized. Go through the code and see is it true? If yes initialized it is.

[Eku]

Yup you can figure that one. Try looking into the tutorials on declaration. Look for how to declare an array. ^_^

[janeansley]

Code:

import java.io.*;

public class Testing
{
   public static void main( String args[] )
   throws java.io.IOException
   {

	   final int PCOUNT = 5000;
	   int a[]= new int[PCOUNT];
	   int i = 0;
	   int j = 0;
	   final double y[]= new double[PCOUNT];


	   String filename, inLine;


	   //keyboard input stream
	   InputStreamReader isr = new InputStreamReader(System.in);
	   BufferedReader br = new BufferedReader(isr);

	   //get the input data
	   System.out.print( "Enter the txt file name(full path): " );
	   filename = br.readLine();

	   //file input stream
	   BufferedReader fi = new BufferedReader(new FileReader(filename));

	   //read existing data and calculate
           while((inLine = fi.readLine()) != null) {
               a[i] = Integer.parseInt(inLine);
               y[j] = ((4.2*a[i]/1010)-1.35);
               i++;
           }
          fi.close();

          try{
		  FileWriter fw = new FileWriter("C:\\output.txt");
		  BufferedWriter out = new BufferedWriter(fw);
		  String Temp = null;
		  	   for(j=0; j<= i; j++){
				   Temp += y[j] + "\n";}
		  out.write(Temp.substring(4));
		  out.close();
                        }catch (Exception A){}

   }

}

Hi, I have initialized for the array and now the program can run finally and save into the output.txt file.
But the there's only a value save in the output.txt file in a row?
Please guide my problems. Thanks.

Quote:

5.0830693069306940.00.00.00.00.00.00.00.00.00.00.0 0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

[Eranga]

You mean that, you want to write line by line, not in a same row? So write a new line in each case.

[janeansley]

Yes, how to make the answer of the calculated value in the output.txt like this?

Quote:

3.764851485148515
3.848019801980198
5.249405940594061
6.891980198019802
3.9062376237623764
6.347227722772278
2.8583168316831684
4.9957425742574255
5.257722772277228
5.199504950495049
3.8812871287128714
3.8812871287128714
3.7814851485148515
5.257722772277228
6.463663366336634
6.833762376237624
5.490594059405941
4.796138613861386
4.326237623762376
5.087227722772278
3.83970297029703
4.796138613861386
3.8771287128712877
5.2909900990099015
5.083069306930694

[Eranga]

Add the following line,

Code:

out.write(System.getProperty("line.separator"));

after the line,

Code:

out.write(Temp.substring(4));

in your code.

[janeansley]

Hi, Eranga. Still the same. I get this in the output.txt file after run.

Quote:

5.0830693069306940.00.00.00.00.00.00.00.00.00.00.0 0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

I wana make the calculated value to be save into the output.txt file,

Quote:

3.764851485148515
3.848019801980198
5.249405940594061
6.891980198019802
3.9062376237623764
6.347227722772278
2.8583168316831684
4.9957425742574255
5.257722772277228
5.199504950495049
3.8812871287128714
3.8812871287128714
3.7814851485148515
5.257722772277228
6.463663366336634
6.833762376237624
5.490594059405941
4.796138613861386
4.326237623762376
5.087227722772278
3.83970297029703
4.796138613861386
3.8771287128712877
5.2909900990099015
5.083069306930694

I have done some research on array, but cannot get it.
Please guide the problems. Thanks

[Eranga]

Show me your new code.

[janeansley]

Code:

import java.io.*;

public class Testing
{
   public static void main( String args[] )
   throws java.io.IOException
   {

	   final int PCOUNT = 5000;
	   int a[]= new int[PCOUNT];
	   int i = 0;
	   int j = 0;
	   final double y[]= new double[PCOUNT];


	   String filename, inLine;


	   //keyboard input stream
	   InputStreamReader isr = new InputStreamReader(System.in);
	   BufferedReader br = new BufferedReader(isr);

	   //get the input data
	   System.out.print( "Enter the txt file name(full path): " );
	   filename = br.readLine();

	   //file input stream
	   BufferedReader fi = new BufferedReader(new FileReader(filename));

	   //read existing data and calculate
           while((inLine = fi.readLine()) != null) {
               a[i] = Integer.parseInt(inLine);
               y[j] = ((4.2*a[i]/1010)-1.35);
               i++;
           }
          fi.close();

          try{
		  FileWriter fw = new FileWriter("C:\\output.txt");
		  BufferedWriter out = new BufferedWriter(fw);
		  String Temp = null;
		  	   for(j=0; j<= i; j++){
				   Temp += y[j] + "\n";}
		  out.write(Temp.substring(4));
		  out.write(System.getProperty("line.separator"));
		  out.close();
                        }catch (Exception A){}

   }

}

I have added the code after that, but still the same at my C:\output.txt
which I get tis answers is not correct:

Quote:

5.0830693069306940.00.00.00.00.00.00.00.00.00.00.0 0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

[Eranga]

First check that you logic is working fine or not. I can see in your code, only the first time do the calculation and after that nothing is changed. Actually the above output is not what you get, isn't it? You get a output stream with an annoying character like '[]', isn't it? Error is not with the new line print, it's an error with your application logic.

[Eku]

hehehe i got your problem. I used \n for next line. if you used notepad to open the file you would see a straigth line. try using Wordpad ^_^ Wordpad can interpret text formatting such as \n. ^_^

Now for the zero output. There is just one wrong variable in the logic. you just have to look for it. Its a simple error ^_^ Try finding it ^_^

HINT: It is inside the while loop

[Eranga]

Quote:

Originally Posted by Eku

HINT: It is inside the while loop

You got the point. Let see our friend can solve it out.

[janeansley]

Hi, thanks Eku and Eranga. I got the right answers now.

The code part changed,

Code:

	   //read existing data and calculate
           while((inLine = fi.readLine()) != null) {
               a[i] = Integer.parseInt(inLine);
               y[j] = ((4.2*a[i]/1010)-1.35);
               i++;
               j++;
           }

I have one more problem is tat the calculated value is not in row by row.

All the output is in one very long row only.

Quote:

3.764851485148515
3.8480198019801985.2494059405940616.89198019801980 23.90623762376237646.3472277227722782.858316831683 16844.99574257425742555.2577227722772285.199504950 4950493.88128712871287143.88128712871287143.781485 14851485155.2577227722772286.4636633663366346.8337 623762376245.4905940594059414.7961386138613864.326 2376237623765.0872277227722783.839702970297034.796 1386138613863.87712871287128775.29099009900990155. 083069306930694
0.0

Can you guide me how to make them in row by row like this?

Quote:

3.764851485148515
3.848019801980198
5.249405940594061
6.891980198019802
3.9062376237623764
6.347227722772278
2.8583168316831684
4.9957425742574255
5.257722772277228
5.199504950495049
3.8812871287128714
3.8812871287128714
3.7814851485148515
5.257722772277228
6.463663366336634
6.833762376237624
5.490594059405941
4.796138613861386
4.326237623762376
5.087227722772278
3.83970297029703
4.796138613861386
3.8771287128712877
5.2909900990099015
5.083069306930694

[Eranga]

Your data written part should be like this.

Code:

    try{
        FileWriter fw = new FileWriter("C:\\output.txt");
        BufferedWriter out = new BufferedWriter(fw);

        for(j=0; j<= i; j++) {
            double Temp = 0;
            Temp += y[j];
            String temp = Double.toString(Temp);
            out.write(temp);
            out.write(s);
            out.flush();
        }
        out.close();
        fw.close();
    }
    catch (Exception A) {
    }

[janeansley]

Hi Eranga, I get this error.

Quote:

Testing.java:48: cannot find symbol
symbol : variable s
location: class Testing
out.write(s);
^
1 error

Where should I declare the variable "s"?

[Eranga]

Ah, that's the new line character I used. Replace it with following.

Code:

out.write("\n");