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Search for pattern in file

Sathya75
Sathya75 asked
on
Hello,
I have a file with the content...
#!/bin/sh
sagemc_loader.exe 100 10 32768 131072 "SAGE Application" dotproduct.ppc_le -d 2 3

I wanted to check for the pattern dotproduct.ppc_le....if that exist return true else false.

How do I acheive this in java???
I know to read a file I can use....FileReader...but how do i match with the pattern????

Please help....
Thanks,
Sathya



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Commented:
Read each line of the file as a String. Check for the index of the pattern using String.indexOf() method. If it returns anything other than -1, it means that the pattern is found.

This method will search for a pattern in a file, and returns true if the pattern is found. Otherwise, it returns false.

public boolean find(String fileName, String pattern) throws IOException {
      FileInputStream fis = new FileInputStream(fileName);
      InputStreamReader isr = new InputStreamReader(fis);
      BufferedReader reader = new BufferedReader(isr);
      String line = null;
      while ( (line = reader.readLine()) != null) {
         if (line.indexOf(pattern) != -1) {
            return true; // pattern found
         }
      }
      return false; // pattern not found
}
hi Sathya ,
 the solution to your problem is in jdk1.4 beta release.
it offers lot flexibility of such type of searching patterns , in a file.
The new packages you have to use

import java.util.regex.*;
import java.nio.*;
import java.nio.charset.*;
import java.nio.channels.*;

i am attaching the sample code for help and implementation.

File Searching

/*
 * Prints out the comments found in a .java file.
 */
import java.util.regex.*;
import java.io.*;
import java.nio.*;
import java.nio.charset.*;
import java.nio.channels.*;

public class CharBufferExample {
    public static void main(String[] args) throws Exception {
        // Create a pattern to match comments
        Pattern p =
            Pattern.compile("//.*$", Pattern.MULTILINE);
       
        // Get a Channel for the source file
        File f = new File("test.java");
        FileInputStream fis = new FileInputStream(f);
        FileChannel fc = fis.getChannel();
       
        // Get a CharBuffer from the source file
        ByteBuffer bb =
            fc.map(FileChannel.MAP_RO, 0, (int)fc.size());
        Charset cs = Charset.forName("8859_1");
        CharsetDecoder cd = cs.newDecoder();
        CharBuffer cb = cd.decode(bb);
       
        // Run some matches
        Matcher m = p.matcher(cb);
        while (m.find())
            System.out.println("Found comment: "+m.group());
    }
}


here you replace the search by your pattern dotproduct.ppc_le in the line pattern.compile.

this i think will solve the problem of searching varied patterns in a file.

Commented:
bhuvneshsharma, please read the guideline below on proposing answers. As your program can only run on JDK1.4, what makes you say that it is the best solution?
Jim CakalicSenior Engineer

Commented:
If you are searching for a simple substring, yongsing's answer is definitely sufficient. (Don't make the solution any more complex or elegant than is demanded by the problem.)

On the other hand, if you want to search for more complex expressions, and you don't want to wait for JDK 1.4 or can't use JDK 1.4, you might consider one of these regex packages:
    http://www.alphaworks.ibm.com/tech/regex4j
    http://jakarta.apache.org/regexp/index.html
    http://jakarta.apache.org/oro/index.html
    http://www.cacas.org/~wes/java/

Best regards,
Jim Cakalic

Commented:
25 questions asked, only 6 graded. The last question graded was 2 years ago.
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Commented:
Moondancer, I noticed that you guys are awarding the points automatically to the proposed answer, even though the proposed answer may not be "a specific solution to a problem". It is unfair to the others who had given comments, which could be better answers than the proposed answer.
Jim CakalicSenior Engineer

Commented:
Did you notice these line from Moondancer's previous posts?

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------------>  EXPERTS:  Please leave any comments regarding your closing recommendations

Jim
Thanks to you both.  yongsing.... it is CRITICAL that the experts in their respective areas of expertise answer our requests.  We are only a handful of Moderators and are handling @ 176 TAs.  We can't know all subjects as the experts.  

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Moondancer - EE Moderator
Proposed Answer rejected.

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Commented:
For this question, I suggest you split the points to the three persons who responded.
Jim CakalicSenior Engineer

Commented:
yongsing responded first with what would appear to be a workable solution. My comment was only intended to direct attention to alternatives, not really a proposed solution to the problem. My recommendation is that yongsing be given the points.

Thanks, Moondancer.
:-)
Thanks to you both...
Points for jim_cakalic -> http://www.experts-exchange.com/jsp/qManageQuestion.jsp?qid=20283076
Split finalized.
Moondancer - EE Moderator

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