Search and Replace

**AtoN** · 02-28-2012, 11:12 AM

Hi Everyone,

I'm writing here because I am new to java and I still not know very well all the framework.

I'm look for making a class method that allow me to "search&replace" text into a file.

Mainly I would like to give to this method 3 input:

- A string with the path to the file (es /home/user/file.txt)
- A string to find (es dog)
- A string to repliche (es cat)

And I would like that all the occurences of "dog"s in the file.txt will be replaced with "cat"s.

I have tryed with "pattern" & "macher" in the java.util.regex.* but I don't understand very well how it works.

Could someone help me please?!?! :(

**Tolls** · 02-28-2012, 11:24 AM

Since you've tried something then you might want to show us that code, and explain where it doesn't work.
That will give us an idea of how far forward you've got, saving us some time (potentially).

**AtoN** · 02-28-2012, 11:36 AM

Ok. I have tryed with this code but at the end I have a file with every string repeted 3 times and replaced "alternatively"

For example. I have to replace dog->cat , lion -> leopard and apple-> banana,

I have this:

cat, lion, apple
dog, leopard, apple
dog, lion, banana

:(

This is the method:

Java Code:

public static void readLineByLine(String destFolder,int processor) throws Exception {
	// First copy the file into the directory
	//BSPXCPAutoConfig.copyfile(CURRENT_DIRECTORY+"/XCP_Template_CProject", destFolder+"/cproject");
	// Read the file and replace text
    File f = new File(CURRENT_DIRECTORY+"/XCP_Template_CProject");
	FileWriter file = new FileWriter (destFolder+"/cproject");
	PrintWriter printer = new PrintWriter(file);
	//Matcher folerMatcher = n
    if (!f.exists() && f.length() < 0) {
            System.out.println("The specified file does not exist");
    } else {
            FileReader fr = new FileReader(f);
            BufferedReader reader = new BufferedReader(fr);
            String st = "";
            String replace;
            if (processor==0)
               replace = "host_if_mb";
            else
            	replace = "mb_"+processor;
            
            while ((st = reader.readLine()) != null) {
                    Pattern p = Pattern.compile("##PROCESSOR_NAME##");
                    Matcher m = p.matcher(st);
                    printer.println(m.replaceAll(replace));
                    // ----------
                    replace = "empty_cpp_bsp_"+processor;
                    p = Pattern.compile("##CPP_BSP_FOLDER##");
                    m = p.matcher(st);
                    printer.println(m.replaceAll(replace));
                    // ----------
                    replace = "BLA BLA";
                    p = Pattern.compile("##PROJECTFOLDER##");
                    // get a matcher object
                    m = p.matcher(st);
                    printer.println(m.replaceAll(replace));
            }
    }
}

**Tolls** · 02-28-2012, 12:08 PM

You are replacing and printing 3 times in your while loop.
You should create your string with everything replaced first, before printing it.

Java Code:

while(blah) {
   ... create first Matcher using 'st' ...
   String current = m.replaceAll(replace);
   .. new Matcher using  'current'...
   current = m.replaceAll(replace);
   ...etc etc...
   printer.println(current);
}