Thread: how to replace a line in a text file

hi gud day everyone;

i want to replace a line in a text file ...and here is my code


import java.io.*;

public class exampletextfile
{
public static void main(String args[])throws IOException
{
BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
File file = new File("StudGrades.itp" );
BufferedReader reader = new BufferedReader(new FileReader(file));
String line="";

System.out.print("Find: " );
String del=input.readLine();

while((line = reader.readLine()) != null)
if(line.contains(del))
{
System.out.print(line );
}



System.out.print("\nReplace with:" );
String replacement=input.readLine();


if(line.contains(del))
{
line= replacement.replace(del,line);
}

FileWriter writer = new FileWriter("StudGrades.itp" );
writer.write(line);
reader.close();
writer.close();

}
}

im done with the displaying of the line my only problem is the replacement part
here's the info i have in the text file

1 090-2012-0032,98.0,90.0,95.0,96.0,95.0
2 090-2012-0033,98.0,90.0,95.0,96.0,95.0

i just want to replace a single line then i need to input the new grades from prelim to finals and compute for the subject grade.

here's my code for that:
(in what part of the program can i insert these codes.?)
System.out.println("Enter Student number:" );
String sn=input.readLine();
System.out.println("Enter prelim grade:" );
p=Integer.parseInt(input.readLine());
System.out.println("Enter midterm grade:" );
m=Integer.parseInt(input.readLine());
System.out.println("Enter prefinal grade:" );
pf=Integer.parseInt(input.readLine());
System.out.println("Enter final grade:" );
f=Integer.parseInt(input.readLine());


sg=(p*.2)+(m*.2)+(pf*.2)+(f*.4);

in my case all lines are being deleted whenever i input the infos.


i hope someone can help me with my program....thanks

Have you thought about reading in the contents of the file, adding the missing line, and then writing a new file?