Question

I’m studying for finals and I’m trying to do the following:

Open the file nFile, and print the string that corresponds to line number start to line number finish, in the file nameFile.

Must handle error message when the line number start or finish do not exist, should print the string “Line not found” if an IOException occurs, the method should print “IO Error”.

I’m using a text file with the following:

11 
1c20 
203 
G2 

If 2,4 is entered, “1c20 203 G2”. will be printed

I have researched a lot and I’m stuck on printing the strings when a line number is entered.

import java.io.*;

public class files { 
public void dR(String nFile, int start, int finish)     
{
        try{                
               FileInputStream fstream = new FileInputStream("C://rest//dat.txt");

               // Get the object of DataInputStream
               DataInputStream in = new DataInputStream(fstream);
               BufferedReader br = new BufferedReader(new InputStreamReader(in));

               nameFile=null;
               start=0;
               finish=0;
                // if start  is greater or = to 1 and finish less than 4
                while((nFile=br.readLine())!=null && start>= 1 && finish <= 4)
                {
                     for(int i=0; i<=start; i++)
                     {
                         System.out.println(nFile);
                         br.close();
                     }
                     System.out.println("that doesnt exsist"); 
                  }            
      } 
            catch(IOException e)
            {
                 System.out.println("there is an IO error");                
            }
        }
    }

Answer 1

you are throwing away all input you get from the parameter

int linenb=1;//this will hold the current line number
while((nFile=br.readLine())!=null){
    if(linenb>=start&&linenb<=finish)  
        System.out.println(nfile); 
    linenb++;
}
if(linenb<=finish)
    System.out.println("Line not found"); 

also add a finally block that will do the close