java regexes problem finding a String in a file
Hi,
My problem is that I am trying to identify one line in a configuration file using Java regexes. That line begins with "upload_target ". My config below (please note it has # comments embedded inside of the file and I want to ignore this):
# Loading a config
upload_target=http://testonetwothree.com
My current code is:
Pattern lineBeginning = Pattern.compile("^upload_target*");
try{
while ((line = writerFileContents.readLine()) !=null){
Matcher m = lineBeginning.matcher(line);
if (m.matches()){
// code that currently never runs to read the line
}
The line I'm looking for is not the first line in the file; I have tried compiling the pattern with the multiline option.
Any help you can offer would be much appreciated.
Thanks
[1122 byte] By [
cup_joea] at [2007-11-27 11:18:30]
I would do it this way:
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class FileRead {
/**
* temp.txt contents
*
* abc jimmy
* def samantha
* ghi tony
* jkl rachel
*
*/
public static void main(String[] args) throws IOException {
Scanner reader = new Scanner(new FileReader("C:\\temp.txt"));
String pattern = "def";
while(reader.hasNext()) {
String currLine = reader.nextLine();
if(currLine.startsWith(pattern)) {
System.out.println(currLine); // prints def samantha
break;
}
}
reader.close();
}
You can also use indexOf on a per line basis if the pattern is not at the start of the line.
Ummm?
What are you trying to accomplish with this:
>> Pattern.compile("^upload_target*");
That pattern is looking for something that DOESNT start with a "u"
and ends in a single "anything" character.
Also, m.matches() checks if the ENTIRE input equals the pattern.
You should probably be using m.find() or change the pattern to this:
Pattern.compile(".*upload_target.*);
You might want to make use of capture groups.
here's a sample.
notice that sample group(0) is always the entire pattern match.
import java.util.regex.*;
public class RegexTester{
public static void main(String[] args){
String text = "blah blah upload_target: some value ; blah blah";
System.out.println("Text: " + text);
String regex = ".*?(upload_target):\\s*(.*?)\\s*;";
System.out.println("Regex: " + regex);
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(text);
while(matcher.find()){
for(int i = 0; i <= matcher.groupCount(); i++){
System.out.println("Match " + (i+1) + ": '" + matcher.group(i) + "'");
}
}
System.out.println("Done");
}
}
> Ummm?
> What are you trying to accomplish with this:
> >> Pattern.compile("^upload_target*");
>
> That pattern is looking for something that DOESNT
> start with a "u"
> and ends in a single "anything" character.
I disagree. It was just missing the period before the asterix.
This works:
Pattern.compile("^upload_target.*");
An example bit of code:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Fubar
{
File inFile = new File(".\\petes\\brief\\inFile.txt");
private Scanner sc = null;
public Fubar()
{
try
{
sc = new Scanner(inFile);
} catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void scanForMatch()
{
Pattern p = Pattern.compile("^upload_target.*");
while (sc.hasNext())
{
String line = sc.nextLine();
System.out.println(line);
Matcher m = p.matcher(line);
if (m.matches())
{
System.out.println("matches: " + line);
}
}
}
public static void main(String[] args)
{
Fubar f = new Fubar();
f.scanForMatch();
}
}
>> I disagree.
Sorry, i wasnt paying attention.
[^u] is 'not u' whereas ^ is the beginning of the line.
and the * means 'any number of'' which my brain swapped with .
The rest of my advice holds.
Using find() will work.
> The rest of my advice holds.
> Using find() will work.
Yep, I don't disagree with that part.
im glad i have your approval, lol.
