Creating new file?

[Aziz]

How would I go about creating a new file (like a .dat file for my highscorelist class)?

I've tried writing to it (thought it would create a new file if the file it was trying to write to didnt exist) so its either that it doesnt work, or it's giving me a NullPointerException for some reason. Here's the code I'm concerned with:

code:

//Creates the highscore file, settings names to "---" and scores to 0         protected void createFile() throws IOException         {                //New PrintWriter to output to highscore file [line 149]  PrintWriter output = new PrintWriter(new FileWriter(fileName));                                //Write as many blank entries as needed                for (int i = 0; i < scores.length - 1; i++)                {                       output.println("---" + "#" + 0 + "$");                }                                //Close stream                output.close();         }

This is the program I'm using to test:

code:

import java.io.*; public class TopList {         public static void main(String[] args) throws IOException         {                 String choice;                                 BufferedReader input = new BufferedReader(new InputStreamReader(System.in));                 HighScoreList myScoresList= new HighScoreList(10, "toplist.txt");                                 do                 {                         System.out.print("Do you want to see the Top List? [Yes/No]");                                         choice = input.readLine();                 } while (choice.toUpperCase() != "YES" && choice.toUpperCase() != "NO");                                                input.close();         } }

and it gives me these run-time errors:

code:

Exception in thread "main" java.lang.NullPointerException       at java.io.FileOutputStream.<init><FileOutputStream.java:172>       at java.io.FileOutputStream.<init><FileOutputStream.java:70>       at java.io.FileWriter.<init><FileWriter.java:46>       at HighScoreList.createFile<HighScoreList.java:149>       at HighScoreList.<init><HighScoreList.java:92> [thats the constructor i call in TopList.java]       at TopList.main<TopList.java:10>

check here for my HighScoreList.class code.

[rizzix]

scores has not been initialised?

[1of42]

Last I checked, the PrintWriter (or maybe it's the FileWriter) will create a new output file if the one you specify doesn't exist yet. Otherwise, you could use the File class to create one, I believe.

[Aziz]

rizzix you're a genius! I believe I didn't do this in my constructors:

code:

scores = new int[size+1];

Which means it didn't have a size. Sweet. I love you man

EDIT: Except it's still giving me the same error. Something with the output stream...

EDIT2: In my createFile() method, I set the line:

code:

PrintWriter output = new PrintWriter(new FileWriter(fileName));

to

code:

PrintWriter output = new PrintWriter(new FileWriter("test.dat"));

and it worked fine. I have no clue what the problem is there [/code]

LAST EDIT:
I got it to work. I think their was errors in the fact that it didn't have a fileName. I think I used the "this" keyword wrong...I better stay away from it