please navigate to cs112 webpage and go to assignments -- Trees. Th.pdf

please navigate to cs112 webpage and go to assignments --> Trees. This will give you the
directions for the assignment. Please do the last 2 methods in huffman.java called encode() and
decode()
Code is provided below:
HuffmanCoding.java
package huffman;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.Collections;
/**
* This class contains methods which, when used together, perform the
* entire Huffman Coding encoding and decoding process
*
* @author Ishaan Ivaturi
* @author Prince Rawal
*/
public class HuffmanCoding {
private String fileName;
private ArrayList sortedCharFreqList;
private TreeNode huffmanRoot;
private String[] encodings;
/**
* Constructor used by the driver, sets filename
* DO NOT EDIT
* @param f The file we want to encode
*/
public HuffmanCoding(String f) {
fileName = f;
}
/**
* Reads from filename character by character, and sets sortedCharFreqList
* to a new ArrayList of CharFreq objects with frequency > 0, sorted by frequency
*/

public void makeSortedList() {
StdIn.setFile(fileName);
/* Your code goes here */
}
/**
* Uses sortedCharFreqList to build a huffman coding tree, and stores its root
* in huffmanRoot
*/
public void makeTree() {
}
/**
* Uses huffmanRoot to create a string array of size 128, where each
* index in the array contains that ASCII character's bitstring encoding. Characters not
* present in the huffman coding tree should have their spots in the array left null.
* Set encodings to this array.
*/
public void makeEncodings() {
}
/**
* Using encodings and filename, this method makes use of the writeBitString method
* to write the final encoding of 1's and 0's to the encoded file.
*
* @param encodedFile The file name into which the text file is to be encoded
*/
public void encode(String encodedFile) {
StdIn.setFile(fileName);
}
/**
* Writes a given string of 1's and 0's to the given file byte by byte
* and NOT as characters of 1 and 0 which take up 8 bits each
* DO NOT EDIT
*

* @param filename The file to write to (doesn't need to exist yet)
* @param bitString The string of 1's and 0's to write to the file in bits
*/
public static void writeBitString(String filename, String bitString) {
byte[] bytes = new byte[bitString.length() / 8 + 1];
int bytesIndex = 0, byteIndex = 0, currentByte = 0;
// Pad the string with initial zeroes and then a one in order to bring
// its length to a multiple of 8. When reading, the 1 signifies the
// end of padding.
int padding = 8 - (bitString.length() % 8);
String pad = "";
for (int i = 0; i < padding-1; i++) pad = pad + "0";
pad = pad + "1";
bitString = pad + bitString;
// For every bit, add it to the right spot in the corresponding byte,
// and store bytes in the array when finished
for (char c : bitString.toCharArray()) {
if (c != '1' && c != '0') {
System.out.println("Invalid characters in bitstring");
return;
}
if (c == '1') currentByte += 1 << (7-byteIndex);
byteIndex++;
if (byteIndex == 8) {
bytes[bytesIndex] = (byte) currentByte;
bytesIndex++;
currentByte = 0;
byteIndex = 0;
}
}
// Write the array of bytes to the provided file
try {
FileOutputStream out = new FileOutputStream(filename);
out.write(bytes);

out.close();
}
catch(Exception e) {
System.err.println("Error when writing to file!");
}
}
/**
* Using a given encoded file name, this method makes use of the readBitString method
* to convert the file into a bit string, then decodes the bit string using the
* tree, and writes it to a decoded file.
*
* @param encodedFile The file which has already been encoded by encode()
* @param decodedFile The name of the new file we want to decode into
*/
public void decode(String encodedFile, String decodedFile) {
StdOut.setFile(decodedFile);
}
/**
* Reads a given file byte by byte, and returns a string of 1's and 0's
* representing the bits in the file
* DO NOT EDIT
*
* @param filename The encoded file to read from
* @return String of 1's and 0's representing the bits in the file
*/
public static String readBitString(String filename) {
String bitString = "";
try {
FileInputStream in = new FileInputStream(filename);
File file = new File(filename);
byte bytes[] = new byte[(int) file.length()];
in.read(bytes);
in.close();

// For each byte read, convert it to a binary string of length 8 and add it
// to the bit string
for (byte b : bytes) {
bitString = bitString +
String.format("%8s", Integer.toBinaryString(b & 0xFF)).replace(' ', '0');
}
// Detect the first 1 signifying the end of padding, then remove the first few
// characters, including the 1
for (int i = 0; i < 8; i++) {
if (bitString.charAt(i) == '1') return bitString.substring(i+1);
}
return bitString.substring(8);
}
catch(Exception e) {
System.out.println("Error while reading file!");
return "";
}
}
/*
* Getters used by the driver.
* DO NOT EDIT or REMOVE
*/
public String getFileName() {
return fileName;
}
public ArrayList getSortedCharFreqList() {
return sortedCharFreqList;
}
public TreeNode getHuffmanRoot() {
return huffmanRoot;
}
public String[] getEncodings() {
return encodings;
}
}

TreeNode.java
package huffman;
/**
* This class represents a node of a huffman coding tree,
* and contains a CharFreq object as its data
*
*/
public class TreeNode {
private CharFreq data;
private TreeNode left;
private TreeNode right;
public TreeNode() {
data = null;
left = null;
right = null;
}
public TreeNode(CharFreq d, TreeNode l, TreeNode r) {
data = d;
left = l;
right = r;
}
public CharFreq getData () {
return data;
}
public void setData (CharFreq data) {
this.data = data;
}
public TreeNode getLeft() {

return left;
}
public void setLeft (TreeNode left) {
this.left = left;
}
public TreeNode getRight() {
return right;
}
public void setRight (TreeNode right) {
this.right = right;
}
}
Queue.java
package huffman;
/**
* This class contains a generic queue class which supports
* isEmpty, size, enqueue, dequeue, and peek. It is implemented
* using a circular linked list.
*
*/
public class Queue {
private Node back;
private int size;
private class Node {
T data;
Node next;
public Node(T d, Node n) {
data = d;

next = n;
}
}
public boolean isEmpty() { return size == 0; }
public int size() { return size; }
public void enqueue(T item) {
size++; // Enqueueing increases the size by 1
// If there were no elements before, make a node that points to itself
if (size == 1) {
back = new Node<>(item, null);
back.next = back;
return;
}
// Otherwise, add a node after back and update back
// Represents adding at the end
back.next = new Node<>(item, back.next);
back = back.next;
}
public T dequeue() {
T item = back.next.data;
size--; // Dequeueing decreases the size by 1
// If there are no elements left, just make back null
if (size == 0) {
back = null;
return item;
}
// Otherwise, remove the front of the list (back.next)
back.next = back.next.next;
return item;
}
public T peek() {
// Just return the data of the front of the queue

return back.next.data;
}
}
CharFreq.java
package huffman;
/**
* This class contains a character object, and a double representing
* its probability of occurrence
*
* @author Prince Rawal
*/
public class CharFreq implements Comparable {
private Character character;
private double probOcc;
// We can set both the Character and double at once
public CharFreq(Character c, double p) {
character = c;
probOcc = p;
}
// No arguments makes a null character and prob 0
public CharFreq() { this(null, 0); }
// Allows us to use Collections.sort() to sort by probOcc
public int compareTo(CharFreq cf) {
Double d1 = probOcc, d2 = cf.probOcc;
if (d1.compareTo(d2) != 0) return d1.compareTo(d2);
return character.compareTo(cf.character);
}
// Getters and setters
public Character getCharacter() { return character; }
public double getProbOcc() { return probOcc; }

public void setCharacter(Character c) { character = c; }
public void setProbOcc(double p) { probOcc = p; }
}
Implementation Notes
YOU MAY only update the methods makeSortedList(), makeTree(), makeEncodings(), encode()
and decode().
DO NOT add any instance variables to the HuffmanCoding class.
DO NOT add any public methods to the HuffmanCoding class.
DO NOT use System.exit() in your code.
DO NOT remove the package statement from HuffmanCoding.java
YOU MAY add private methods to the HuffmanCoding class.

please navigate to cs112 webpage and go to assignments -- Trees. Th.pdf

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please navigate to cs112 webpage and go to assignments -- Trees. Th.pdf