joeF

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since Dec 15, 2002

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Recent posts by joeF

keyword search question

Thanks.

21 years ago

Java in General

keyword search question

Hi:
I am working on a problem that requires that I find a keyword within a text file. I have tokenized the input and I can easily locate the keyword as an exact token match but if the keyword appears within a token then it is missed.
example:
keyword = mary
File contains "mary had a little lamb". Keyword is found.
File contains "littlemary had a lamb". Keyword is not found.
Can someone please help me solve the problem?
Thanks.

21 years ago

Java in General

Text to tokens?

Thanks.

21 years ago

Java in General

Text to tokens?

Hi:
I know that I can break a string into tokens by using StringTokenizer
but how do I accomplish this task if I am using FileReader to read the file as characters?
(if possible please provide sample code)
Thanks.

21 years ago

Java in General

BufferedReader Problem

It works after a second try.
???
Thanks.

21 years ago

Java in General

BufferedReader Problem

Hi:
I trying to display on the screen text from multiple files. I am only able to display the first file. Can somone look at my code and tell me the reason and a possible solution?
Thanks.

[ December 18, 2002: Message edited by: Cindy Glass ]

21 years ago

Java in General

Ecryption program question

Hi:
I changed my name in the profile.
Regards,
Joe

21 years ago

Java in General

Ecryption program question

Hi:
I written an monoalphabet substitution encryption program. Can anyone point out mistakes or areas in which the code could be improved?
Thanks.

import java.io.FileReader;
import java.io.FileWriter;
import java.io.BufferedReader;
/**
A command line encryption program.
@version 1.0
*/
public class Monoalphabet
{
public static void main(String args[])
{
int positionOfA = 'a';
int positionzOfz = 'z';
char [] cypher = null;
boolean decrypt = false;
FileWriter out = null;
FileReader in = null;
try
{
if (args.length < 3 || args.length > 5) usage();
for (int i = 0; i < args.length; i++)
{
if (args[i].substring(0, 1).equals("-"))
{ String option = args[i].substring(1, 2);
if (option.equals("d"))
{ String keyword = args[i + 1];
if (keyword.length() <= 2) missingKeyword();
System.out.println(keyword.length());
String keyTest = args[i + 1].substring(2, keyword.length());
for (int j = 0; j < keyTest.length(); j++)
{
char test = keyTest.charAt(j);
int k = (int) test;
System.out.println(k);
if (k < positionOfA || k > positionzOfz)
{
missingKeyword();
}
else
{
String key = keyTest;
cypher = makeCypher(removeDups(key));
decrypt = true;
}
}
}
else if (option.equals("k"))
{
String keyword = args[i];
if (keyword.length() <= 2) missingKeyword();
{ String keyTest = args[i].substring(2, keyword.length());
for (int j = 0; j < keyTest.length(); j++)
{
char test = keyTest.charAt(j);
int k = (int) test;
System.out.println(k);
if (k < positionOfA || k > positionzOfz)
{ missingKeyword();
}
}
}
String key = args[i].substring(2, keyword.length());
cypher = makeCypher(removeDups(key));
}
}
else
{ if (in == null)
{
in = new FileReader(args[i]);
}
else if (out == null)
{
out = new FileWriter(args[i]);
}
}
}
}
catch (Exception e)
{ e.printStackTrace();
System.out.println("Exception: " + e);
}
if (in == null || out == null) usage();
try
{ if (decrypt)
{ decrypt(in, out, cypher);
in.close();
out.close();
}
else
{ encrypt(in, out, cypher);
in.close();
out.close();
}
}
catch (Exception e)
{ System.out.println("Exception: " + e);
System.exit(0);
}
}
/**
Prints a message regarding a missing keyword.
*/
public static void missingKeyword()
{
System.out.println("Missing Keyword");
System.exit(1);
}
/**
Prints a message describing proper usage and then exits.
*/
public static void usage()
{ System.out.println
("Usage: java Monoalphabet [-d] [-kkeyword] infile outfile");
System.exit(1);
}
/**
A decryption method.
@param in The input file.
@param out The output file.
@param cypher A character array.
*/
public static void decrypt(FileReader in, FileWriter out, char [] cypher)
{ int positionOfA = 'a';
int alphabet = 26;
char [] alpha = new char[alphabet];
for (int i = 0; i < alpha.length; i++)
{ alpha[i] = (char)(i + positionOfA);
}
BufferedReader infile = new BufferedReader(in);
try
{
while (true)
{
{ int next = in.read();
if (next == -1) return;
char whatever = (char) next;
if (Character.isLetter(whatever))
{ for (int i = 0; i < cypher.length; i++)
{ if (cypher[i] == whatever)
{
int position = i;
char ch = alpha[i];
out.write(ch);
}
}
}
else
{
char ch = whatever;
out.write(ch);
}
}
}
}
catch (Exception e)
{
System.out.println("Exception: " + e);
}
}
/**
An encryption method.
@param in The input file.
@param out The output file.
@param cypher A character array.
*/
public static void encrypt(FileReader in, FileWriter out, char[] cypher)
{ int positionOfA = 'a';
BufferedReader infile = new BufferedReader(in);
try
{
while (true)
{
{ int next = in.read();
if (next == -1) return;
char whatever = Character.toLowerCase((char)next);
if (Character.isLetter(whatever))
{
char ch = cypher[(int)whatever - positionOfA];
out.write(ch);
}
else
{
char ch = whatever;
out.write(ch);
}
}
}
}
catch (Exception e)
{
System.out.println("Exception: " + e);
}
}
/**
A method for removing duplicate letters from a string.
@param key A keyword used for encryption.
@return keep A string with a keyword plus reverse alphabet
with duplicate letters removed.
*/
public static String removeDups(String key)
{
String keep = "";
key = key + "zyxwvutsrqponmlkjihgfedcba";
System.out.println("The key is " + key);
for (int i = key.length() - 1; i > -1 ; i--)
if (i == key.indexOf(key.charAt(i)))
{
keep = key.charAt(i) + keep;
}
return keep;
}
/**
A method for copying a string to a character array.
@param keep A string containing a keyword and reverse alphabet.
@return keepArray Character array containing a keyword plus
reverse alphabet.
*/
public static char[] makeCypher(String keep)
{
char keepArray [];
keepArray = keep.toCharArray();
return keepArray;
}
}

(edited by Cindy to change backslash to slash so that code tags would work)
[ December 16, 2002: Message edited by: Cindy Glass ]
[ December 16, 2002: Message edited by: joeF ]

21 years ago

Java in General