Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class Main {
    public static boolean encodeLZW(String inText, int dictSize, int[] encodedData) {
        int[] returnData = { 0 };
        try {
            encodedData = new int[inText.length()];
            int outCount = 0;
            HashMap<Integer, String> dict = newDictLZW(inText);

            String teststring = "";
            for (int i = 0; i < inText.length() - 1; i++) {
                teststring = String.valueOf(inText.charAt(i));
                String prevstring = teststring;
                int j = 0;
                // System.out.println("teststring = " + teststring +
                // ";  prevstring= " + prevstring + ";  i= " + i);
                while (dict.containsValue(teststring) && i + j < inText.length() - 1) {
                    prevstring = teststring;
                    j++;
                    teststring = teststring.concat(String.valueOf(inText.charAt(i + j)));
                }
                // get key value for the string that matched
                Integer mapIndex = (getKeyByValue(dict, prevstring));

                // add this key to the encoded outText as string (ASCII 8 bit) outText =
                // outText.concat(String.valueOf(((char)Integer.parseInt(mapIndex))));

                encodedData[outCount] = mapIndex;

                outCount++;
                // add to dictionary the string that matched plus the next char in
                // sequence in inText
                // test that the new dictionary entry is not in the dictionary and
                // does not contain the new-line character
                if (!dict.containsValue(teststring) && teststring.charAt(teststring.length() - 1) != '\n'
                        && dict.size() < dictSize)
                    dict.put(dict.size(), teststring);

                // set index value i to point to that next char in sequence
                i = i + j - 1;
            }
            // TODO add switch to turn printing on and off
            System.out.println("\n-- Dictionary --");
            printDictionary(dict);

            returnData = new int[outCount]; // count entries and use here.
            for (int i = 0; i < outCount; i++) {
                returnData[i] = encodedData[i];
            }
            encodedData = returnData;
        } catch (Exception ex) {
            System.err.println(
                    "---------------------------------------------\nencodeLZW() method failed\nprobably tried to encode an incompatable file\n---------------------------------------------");
            return false;
        }
        return true;
    }

    public static HashMap<Integer, String> newDictLZW(String inMsg) {
        HashMap<Integer, String> dict = new HashMap<Integer, String>();
        int j = 0;

        for (int i = 0; i < inMsg.length(); i++) {
            if (dict.containsValue(Character.toString(inMsg.charAt(i))) == false && inMsg.charAt(i) != '\n') {
                dict.put((Integer) j, Character.toString(inMsg.charAt(i)));
                j++;
            }
        }
        return dict;
    }

    public static Integer getKeyByValue(Map<Integer, String> map, String value) {
        for (Entry<Integer, String> entry : map.entrySet()) {
            if (value.equals(entry.getValue())) {
                return entry.getKey();
            }
        }
        return null;
    }

    public static void printDictionary(HashMap<Integer, String> dict) {
        System.out.println("Index\t\tEntry\n---------------------");
        for (int i = 0; i < dict.size(); i++) {
            System.out.println(i + "\t\t" + dict.get(i));
        }
    }
}