Seachring word from text file

Question

Hi...There..
I h'va wrirtten Search application which search words from Simple text files.
My file contains list of words separated by "\n"(new line).
i am using java.io.BufferedReader for reading file.
i'want to search word from file within few milliseconds, but when my file containo more then some 2lake words(200000) my process of readind comsumes more then 5 sec. time to search.
pl. suggest me effective method to search word from file so i can make it rapid search.
Actually i 've to provide search on "TEXT VALUE CHANGED EVENT" so even if my process takes more then one seconds it is not physible for me.
Thanks in Advance.
Timir Patel.

Answer 1

Try this:
import java.io.*;
import java.util.*;
public class searcher
          private static long [] indexes;
     private static class temp_data
          public final String text;
          public final long starts_at;
          public temp_data(String t, long l)
               text = t;
               starts_at = l;
     private static class temp_cmp implements Comparator
          public int compare(Object o1,Object o2)
               return ((temp_data)o1).text.compareTo(
                         ((temp_data)o2).text);
     /** creats index table. You should do it once, and rather store index
     table in file then. This method has high peak memory usage but it is
       easy to optimize it.*/
     private static void buildIndex(RandomAccessFile file)throws Exception
          List temp = new LinkedList();
          String st;
          long p = file.getFilePointer();
          while((st = file.readLine())!=null)
               temp.add(
                    new temp_data(st,p)
               p = file.getFilePointer();
          Collections.sort(temp,new temp_cmp());
          indexes = new long[temp.size()];
          int i=0;
          for(Iterator I=temp.iterator();I.hasNext();i++)
          temp_data tt = ((temp_data)I.next());
           System.out.println("indexing :"+tt.text+" ["+tt.starts_at+"]");
               indexes=tt.starts_at;
     /** returns position at which text starts or -1 if not found */
     public static long find(String text,RandomAccessFile file)throws Exception
          int ncp = indexes.length/2;
          int n = 2;
          int cp;
          do{
          cp = ncp;
               file.seek(indexes[cp]);
               String tt = file.readLine();
          System.out.println("comparing with "+tt);
               int cmpr = text.compareTo(tt);
               if (cmpr==0)
                    return indexes[cp];
               else
               if (cmpr>0)
                    ncp = cp+(indexes.length / (1<<n));
               else
                    ncp = cp-(indexes.length / (1<<n));
               n++;
          }while(ncp!=cp);
          return -1;
     public static void main(String args [] )throws Exception
          RandomAccessFile f = new RandomAccessFile(args[0],"r");
          buildIndex(f);
          for(int i=1;i<args.length;i++)
          System.out.println("searching for \""+args[i]+"\"");
          System.out.println("found at:"+find(args[i],f));
          f.close();
It should work, however I gave it less than five minutes testing.