java 正则表达式进行剔除字符

package com.regular;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class testRegular {

private static Pattern pattern = Pattern.compile("^\\d{1,3}\\.");
private static Matcher matcher = null;
public static StringBuffer removeOtherCharacter(File file){
   try {
    BufferedReader reader = new BufferedReader(new FileReader(file));
    StringBuffer buffer = new StringBuffer();
    String line = new String();
    line = reader.readLine();
    while(line != null){
     buffer.append(remove(line));
     buffer.append("\n\r");
     line = reader.readLine();
    }
    return buffer;
   } catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   return null;
}
private static String remove(String source){
   matcher = pattern.matcher(source);
  
   return matcher.replaceAll("");
}

public static void writeSourceFile(StringBuffer buffer){
   File file = new File("src/com/regular/file_new.txt");
   if(!file.exists()){
    try {
     file.createNewFile();
    } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
  
   try {
    BufferedWriter writer = new BufferedWriter(new FileWriter(file));
    writer.write(buffer.toString());
    writer.flush();
    writer.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
}
public static void main(String[] args) {
   File file = new File("src/com/regular/file.txt");
   StringBuffer buffer = removeOtherCharacter(file);
  
   writeSourceFile(buffer);
}
}