CODEWITHSUNDEEP
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Jevison7x
Jevison7x

Reputation: 737

How to search for a word in a file using java

I am writing a java program to search for a word in a text file containing a list of words in the dictionary. As you may now, this file contains about 300,000 words. I was able to come up with a program that can iterate through the words comparing each word with the input word (the word I am searching for). The problem is that this process takes a lot of time to find a word especially if the word starts with the last alphabets like x, y, or z. I want something more efficient that can find a word almost instantly. Here is my code:

import java.io.IOException;
import java.io.InputStreamReader;

public class ReadFile
{
public static void main(String[] args) throws IOException
{
    ReadFile rf = new ReadFile();
    rf.searchWord(args[0]);
}

private void searchWord(String token) throws IOException
{
    InputStreamReader reader = new InputStreamReader(
            getClass().getResourceAsStream("sowpods.txt"));
    String line = null;
    // Read a single line from the file. null represents the EOF.
    while((line = readLine(reader)) != null && !line.equals(token))
    {
        System.out.println(line);
    }

    if(line != null && line.equals(token))
    {
        System.out.println(token + " WAS FOUND.");
    }
    else if(line != null && !line.equals(token))
    {
        System.out.println(token + " WAS NOT FOUND.");
    }
    else
    {
        System.out.println(token + " WAS NOT FOUND.");
    }
    reader.close();
}

private String readLine(InputStreamReader reader) throws IOException
{
    // Test whether the end of file has been reached. If so, return null.
    int readChar = reader.read();
    if(readChar == -1)
    {
        return null;
    }
    StringBuffer string = new StringBuffer("");
    // Read until end of file or new line
    while(readChar != -1 && readChar != '\n')
    {
        // Append the read character to the string. Some operating systems
        // such as Microsoft Windows prepend newline character ('\n') with
        // carriage return ('\r'). This is part of the newline character
        // and therefore an exception that should not be appended to the
        // string.
        if(readChar != '\r')
        {
            string.append((char) readChar);
        }
        // Read the next character
        readChar = reader.read();
    }
    return string.toString();
}

}

Please also note that I would like to use this program in a Java ME environment. Any help would be highly appreciated thanks - Jevison7x.

Upvotes: 1

Views: 11917

Answers (1)

nhahtdh
nhahtdh

Reputation: 56809

You can use fgrep (fgrep is activated by -F to grep) (Linux man page of fgrep):

grep -F -f dictionary.txt inputfile.txt

The dictionary file should contain the words one on each line.

Not sure if it is still accurate, but Wikipedia article on grep mentions the use of Aho-Corasick algorithm in fgrep, which is an algorithm that builds an automata based on a fixed dictionary for quick string matching.

Anyway, you can have a look at the list of string searching algorithms on a finite set of patterns on Wikipedia. These are the more efficient ones to work with when searching for words in dictionary.

Upvotes: 1

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