Searching a text file using Java

Raskolnikov

I need to scan through a text file checking for the first number on each line and comparing it to a number that the user has already inputted. The text file has the format . . .

1 Blah Blah Blah
2 Blah Blah Blah
3 . . ... . . . . . .. . . . . . etc

I've got no problem getting the user input, it's just scanning each line, to check if the number the user entered is equal to the one at the begining of each line.

Can anyone help?

scojones

Show your code, buddy

Raskolnikov

[PHP] private void buyCd()
{
try {
FileInputStream fis = new FileInputStream("cds.txt");
int n;
while ((n = fis.available()) > 0) {
byte[] b = new byte[n];
int result = fis.read(b);
if (result == -1) break;
String s = new String(b);
System.out.print(s);
} // End while
} // End try
catch (IOException e) {System.err.println(e);}
System.out.println();

readValue();

RandomAccessFile raf = new RandomAccessFile("cds.txt","rw");
StringBuffer beforeDelete = new StringBuffer();
boolean found = false;
while(raf.getFilePointer() != raf.length())
{
String compareAgainst = raf.readLine();

if(compareAgainst.equals(instr))
{
found = true;
toDelete = compareAgainst.length() + 1;
}
else
{
beforeDelete.append(compareAgainst + "\n");
}
}
}[/PHP]

Raskolnikov

You can ignore the whole random access file bit after readValue(); that was just my attempt at finding the value, hasn't worked for me and there is probably an easier way.

scojones

Originally posted by Raskolnikov
I need to scan through a text file checking for the first number on each line and comparing it to a number that the user has already inputted. The text file has the format . . .

1 Blah Blah Blah
2 Blah Blah Blah
3 . . ... . . . . . .. . . . . . etc

I've got no problem getting the user input, it's just scanning each line, to check if the number the user entered is equal to the one at the begining of each line.

Can anyone help?

Before i go on... let me get this straight, all you want to do is get the content of the line, who's line number == user input? Or do you just want to check that a line with that number exists? (i.e 1,2,3...(n)).

Raskolnikov

Originally posted by sjones
Before i go on... let me get this straight, all you want to do is get the content of the line, who's line number == user input? Or do you just want to check that a line with that number exists? (i.e 1,2,3...(n)).

I just want to check the number at the start of each line, if the number matches the user input, I want the line in the text file returned, else return an error.

1 Boyzone Love Me For a Reason ISland Records 10 Pop 19.99
2 NWA Straight Outta Compton Nigaa Records 20 Rap 10.99
3 King Crimson ThrakAttack Island Records 2 Rock 0.99
4 Roger Taylor I'm A Git Self-Released 1000 PapRock 10.99

That's what gets printed out to the user, they select the number of the cd they want, I need to then search the cds.txt to match them.

Enygma

2nd year UCC by any chance?

Here's the pseudocode:

foreach line in the file
   if line startsWith userInput
      return line

Use a StringTokenizer then to split up the line into it's own parts

Raskolnikov

Yep.

Found a solution, thanks anyway.

Draupnir

Doesnt anyone use BufferedReader these days?