Regular Expressions on the Contents of a File

[samualres]

Hello, I am learning java programming and while learning it, I am not able to understand the Regular Expressions on the Contents of a File. I have use different sources for it, but all of them are useless. So, if you are having any solution to achieve it, then please help me to achieve it. If you know how to apply Regular Expressions on the Contents of a File then provide source code for that.

[MindSpace]

Hello, if you want to apply the regular expressions on the content of the file then you must need to make use of the following methods and classes:
Methods:

• FileInputStream(filename).getChannel()
• Charset.newDecoder()
• Charset.decode()

Classes:

• FileChannel
• CharBuffer
• Charset

[Modifier]

Hello, for Applying Regular Expressions on the Contents of a File you need to use the code below. Just create a class and then add all of the code in that and get your problem solved.

try 
{ 
Pattern P = Pattern.compile("P");
Matcher M = P.M(fromFile("FileName.txt")); 
while (M.find()) 
{ 
String str = M.group(); 
} 
} 
catch (IOException e) 
{ 
}

[opaper]

For getting better solution on this you can simply make use of the books below and solve your problem:

• The Java developers almanac 1.4: examples and quick reference
• Automating InDesign with Regular Expressions‎
• Java regular expressions: taming the java.util.regex engine‎
• Thinking in Java‎
• Mastering regular expressions‎

[Praetor]

For getting the regular expressions on the content of a file you must need to use the code provided below:

import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main 
{
  public static CharSequence fromFile(String filename) throws IOException 
{
    FileInputStream fileinputstream = new FileInputStream(filename);
    FileChannel filechannel = fileinputstream.getChannel();
    ByteBuffer bytebuffer = filechannel.map(FileChannel.MapMode.READ_ONLY, 0, (int) filechannel.size());
    CharBuffer charbuffer = Charset.forName("8859_1").newDecoder().decode(bytebuffer);
    return charbuffer;
  }
  public static void main(String[] argv) throws Exception 
{
    Pattern patt = Pattern.compile("patt");
    Matcher match = patt.match(fromFile("infile.txt"));
    while (match.find()) 
{
      String string = match.group();
    }
  }
}