Reading from a text file

[keko4201]

whats up guys, got some more questions. we are starting to learn how to write and read strings to/from txt files. wel thats pretty easy, but how would i retrieve only the first 2 lines of the txt file, for example, if i wanted the first 2 lines, not any other, how would i do it:
12 <--i only need this one and
90 <--this one
12
6
-9

how would i go baout doin this.
thnks

-keko-

[ray326]

BufferedReader has a readLine() method that would be handy for that.

[keko4201]

umm, where would i find this method, cause i know sun has a page with all the methods availible to java. so maybe u can elaberate on what u said above or if u have a link to sun's java source page, cause i cant find it. thnks
\
-wes-

[ray326]

http://java.sun.com/j2se/1.5.0/docs/...redReader.html

[keko4201]

ok got the readline to kinda work. im reading from a txt file that contains 10 integers on 10 different lines. i need to read the first 2 lines, and get there some, thenm i need to read the next 2 lines. and add them up and etc..

i got it to read from the file, but its not wokring right, it doesnt read the first line when i tell it to print and it only prints 5 lines? why is htis,
/////////////////////////////////////////////////////////////////////
this is the contenst of the file

5
5
-10
4
0
5
6
0
8
-4



/////////////////////////////////////////////////////////////////////

import java.io.*;
import javax.swing.JOptionPane;


public class wes{


public static void main(String[] args)throws Exception{



FileReader inStream = new FileReader("C:\\myText.txt");

BufferedReader buffer = new BufferedReader(inStream);

int numLines=Integer.parseInt(buffer.readLine()); //got thsi from an example, but it only reads the first line. which in the end messes upthe loop below? should i loop this to get a count?


for(int lCount=0;lCount<numLines;lCount++){


String data = buffer.readLine();
System.out.println("de"+ data);
}

System.out.println("number of lines " + numLines );


buffer.close();
System.exit(0);




}


}

[keko4201]

ok, so dont pay no attention to the above reply. i believe thsi is the way to get everything done, everyhtign is the same as the print out my teacher gave us. the only thing is, how do i line everything up evenly. if u run this in JCreator or whatever u using, u will see how unaligned everything is, can someone help meo ut on how to align everyhting perfectly


also, is this a correct way of writing thios program?
-thnks-
-wes-

import java.io.*;
import javax.swing.JOptionPane;


public class wes{


public static void main(String[] args)throws Exception{



FileReader inStream = new FileReader("C:\\myText.txt");
BufferedReader buffer = new BufferedReader(inStream);




String data;
data = buffer.readLine();
int add = 0;
int diff = 0;
int prod = 0;

System.out.println("Operand #1 " + " " + "Operand #2" + " " + " Sum " + " Difference" + " Product ");
while(data!=null){


int d1 = Integer.parseInt(data);


data = buffer.readLine();

int d2 = Integer.parseInt(data);
add = d1 + d2;
diff = d1 - d2;
prod = d1 * d2;

System.out.println(" " + d1 + " " + d2 + " " + add + " " + diff + " " + prod);

data = buffer.readLine();

}

buffer.close();
System.exit(0);

}


}

[buntine]

The reason its only printing the first five lines is because your storing the value of the first line in the numlines variable, which is 5.

You could use a while loop instead.

String data = buffer.readLine();
while (data != null)
{
   ...
   data = buffer.readLine();
}

Regards.

[keko4201]

yea i did that. as soon as i postedthat i was having trouble, i went back and figured ito ut, thats hwy i wrote dont pay no attention to that reply, i did have a question again with new code if u wanna look at, scrool up, should be right above ur last post,

thnks for the help

-keko-

[Jesdisciple]

JCreator has a feature which indents each line of a block of text if you highlight multiple lines and press Tab (Shift+Tab does the opposite).

I did have a related question, but the program suddenly worked as I was typing this reply. For future reference, do you prefer a new thread for a similar problem?

[agent_x91]

If it's an unrelated problem, you may wish to make your own thread: you're likely to get more attention if you have asked your own separate queston. Good luck.