Making a program for parents..need help.

[GUImaster]

Im making a program for my parents...and i got stuck. a part of what i need to do is
**Using Netbeans 6.8**

*Needs Button*
*Needs TextField*
---------------------------------------------------------------------------------
Check To see if "input.txt" is empty

if "input.txt" is empty then
write "This is Header"
write "----------------"
write (Text in TextField)

if "input.txt" isnt empty then

append at end of file (Text in TextField)
--------------------------------------------------------------------------------


i had a basic idea of what i needed to do but it didnt work out for me

Thanks in Advance

[Zren]

Here's some code snippets to point you in a general direction of File Input/Output. Buttons are rather easy in netbeans so that shouldn't be the problem. If ya need more details just ask.

To find if the file exist (Copy n Paste, this forum doesn't like the brackets at the end. Or just look for exists yourself): http://download.oracle.com/docs/cd/E17476_01/javase/1.4.2/docs/api/java/io/File.html#exists()

File Size:

Java:

File f = new File("blarg.txt"); long file_size = f.length();

For writing to files: [Source]

Java:

import java.io.*; class FileWrite {    public static void main(String args[]) {       try {         // Create file         FileWriter fstream = new FileWriter("out.txt");         BufferedWriter out = new BufferedWriter(fstream);         //Trick: BufferedWriter out = new BufferedWriter( new FileWriter("out.txt") );         out.write("Hello Java");         //Close the output stream         out.close();     } catch (Exception e) { //Catch exception if any         System.err.println("Error: " + e.getMessage());     }   } }

Don't forget to close or flush the bufferedwriter or nothing will write to file.

[GUImaster]

i have import.java.io.*;
and this code happens when the button is pressed

code:

try {             fis = new FileInputStream("input.txt");                         in = new DataInputStream(fis);             temp = in.readLine();             in.close();                         fwriter5 = new FileWriter("input.txt", true);             bfwriter2 = new BufferedWriter(fwriter5);             if (temp.compareTo(" ")==0) {                 bfwriter2.write("Hello");                 bfwriter2.write("------------------");                 bfwriter2.write(jTextField1.getText());                             } else  {                                  // bfwriter2.write(jTextField1.getText());             }                   } catch (IOException ex) {             Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);         }

thats what i have after using netbeans gui bulder... but it doesnt work for me

[Zren]

Did you clooooo~se the buffered writer?

[GUImaster]

i dont exactly know where to close it....the try catch things always throw me off

[Update] I closed it in the if statement and i got the same error}

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

[GUImaster]

I got it working now...Thanks for the help

i changed the if (Temp.compareTo(" ")==0) to if (temp == null)