Mega Code Archive
This class is an implementation of the ROT-N algorithm
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/*
* Copyright WizTools.org
* Licensed under the Apache License, Version 2.0:
* http://www.apache.org/licenses/LICENSE-2.0
*/
//package org.wiztools.commons;
import java.util.HashMap;
import java.util.Map;
/**
* This class is an implementation of the ROT-N algorithm. The algorithm
* implemented in this class dynamically creates the lookup table.
* @author subhash
*/
public final class RotN {
private RotN() {}
private static final char[] lookup = "abcdefghijklmnopqrstuvwxyz".toCharArray();
private static interface Emitter {
void emit(char c1, char c2);
}
private static void map(final int n, final Emitter emitter) {
if(n < 1 || n > 25)
throw new IllegalArgumentException("Value of N should be between 1 and 26");
for(int i=0, j=n; i<lookup.length; i++,j++) {
if(j == lookup.length)
j = 0;
emitter.emit(lookup[i], lookup[j]);
}
}
private static Map<Character, Character> getCipherMap(final int n) {
final Map<Character, Character> out = new HashMap<Character, Character>();
Emitter emitter = new Emitter() {
@Override
public void emit(char c1, char c2) {
out.put(c1, c2);
}
};
map(n, emitter);
return out;
}
private static Map<Character, Character> getDeCipherMap(final int n) {
final Map<Character, Character> out = new HashMap<Character, Character>();
Emitter emitter = new Emitter() {
@Override
public void emit(char c1, char c2) {
out.put(c2, c1);
}
};
map(n, emitter);
return out;
}
private static String process(final String inString,
final Map<Character, Character> map) throws IllegalArgumentException {
char[] arr = inString.toCharArray();
StringBuilder sb = new StringBuilder(arr.length);
for(char c: arr) {
Character out = map.get(c);
if(out == null) {
sb.append(c);
}
else {
if(Character.isUpperCase(c))
sb.append(Character.toUpperCase(out));
else
sb.append(out);
}
}
return sb.toString();
}
/**
* To cipher a String using ROT-N algorithm.
* @param n The value of N in ROT-N.
* @param inString The input string.
* @return The ciphered value.
* @throws IllegalArgumentException When n is not within range.
*/
public static String cipher(final int n, final String inString) throws IllegalArgumentException {
return process(inString, getCipherMap(n));
}
/**
* To decipher a String using ROT-N algorithm.
* @param n The value of N in ROT-N.
* @param inString The input string.
* @return The deciphered value.
* @throws IllegalArgumentException When n is not within range.
*/
public static String deCipher(final int n, final String inString) throws IllegalArgumentException {
return process(inString, getDeCipherMap(n));
}
}
---------------
/*
* Copyright WizTools.org
* Licensed under the Apache License, Version 2.0:
* http://www.apache.org/licenses/LICENSE-2.0
*/
package org.wiztools.commons;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.junit.Assert.*;
/**
*
* @author subhash
*/
public class RotNTest {
public RotNTest() {
}
@BeforeClass
public static void setUpClass() throws Exception {
}
@AfterClass
public static void tearDownClass() throws Exception {
}
@Before
public void setUp() {
}
@After
public void tearDown() {
}
/**
* Test of cipher method, of class RotN.
*/
@Test
public void testCipher() {
System.out.println("cipher");
int n = 13;
String inString = "subhash-101-aarthi";
String expResult = Rot13.cipher(inString);
String result = RotN.cipher(n, inString);
assertEquals(expResult, result);
}
/**
* Test of deCipher method, of class RotN.
*/
@Test
public void testDeCipher() {
System.out.println("deCipher");
int n = 13;
String inString = Rot13.cipher("subhash-101-aarthi");
String expResult = "subhash-101-aarthi";
String result = RotN.deCipher(n, inString);
assertEquals(expResult, result);
}
}
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