Rot13.java Source code

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Here is the source code for Rot13.java

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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.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * An implementation of the ROT-13 algorithm. The lookup table is defined as a
 * constant in the code: making this implementation pretty fast.
 * @author subhash
 */
public final class Rot13 {

    private static final Map<Character, Character> map;
    static {
        final char[] lookup1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();
        final char[] lookup2 = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm".toCharArray();

        Map<Character, Character> m = new HashMap<Character, Character>();
        for (int i = 0; i < lookup1.length; i++) {
            m.put(lookup1[i], lookup2[i]);
        }
        map = Collections.unmodifiableMap(m);
    }

    private Rot13() {
    }

    /**
     * Converts the input string ROT-13 algorithm.
     * @param inStr The input string.
     * @return The ROT-13ed version of the input string.
     */
    public static String cipher(final String inStr) {
        char[] arr = inStr.toCharArray();
        StringBuilder sb = new StringBuilder(arr.length);

        for (char c : arr) {
            Character out = map.get(c);
            if (out == null) {
                sb.append(c);
            } else {
                sb.append(out);
            }
        }

        return sb.toString();
    }
}