Java Programming: Modify the classes below to do so Evaluator Class public class

ID: 3720721 • Letter: J

Question

Java Programming:

Modify the classes below to do so

Evaluator Class

public class EvaluateExpression {

private static Dictionary variables;
public static double solveExpression(String expression) {
char[] tokens = expression.toCharArray(); // make sure you delete all the white spaces
//Number Stack
Stack<Double> valueStack = new Stack<>();
//Operator Stack
Stack<Character> opsStack = new Stack<>();

for (int i = 0; i < tokens.length; i++) {
if(tokens[i] == ' ') continue; // if current character is a space, ignore it

if ( Character.isDigit(tokens[i])) { // if current character is a digit, then
StringBuilder sbuf = new StringBuilder(); // string builder is more faster than StringBuffer
while (i < tokens.length && (Character.isDigit(tokens[i]) || (tokens[i] == '.'))) {
sbuf.append(tokens[i++]);
}
valueStack.push(Double.parseDouble(sbuf.toString()));
} else if (tokens[i] == '(') {
opsStack.push(tokens[i]);
} else if (tokens[i] == ')') {
while (opsStack.peek() != '(') {
valueStack.push(performOperation(opsStack.pop(), valueStack.pop(), valueStack.pop()));
}
opsStack.pop();
} else if (isOperator(tokens[i])) { // if current character is an operator, then
while (!opsStack.empty() && isPrecedence(tokens[i], opsStack.peek())) {
valueStack.push(performOperation(opsStack.pop(), valueStack.pop(), valueStack.pop()));
}
opsStack.push(tokens[i]);
} else { // if it is neither a digit nor a operator, it might be a variable
try {
StringBuilder sbuf = new StringBuilder(); // string builder is more faster than StringBuffer
while (i < tokens.length && (Character.isAlphabetic(tokens[i]))) { // read all the characters of variable
sbuf.append(tokens[i++]); // read the characters of the variable
}
String varialbe = sbuf.toString(); // get the name of the variable
double val = variables.lookup(varialbe); // get the value of the expression

valueStack.push(val);
} catch (HashException | NullPointerException ex) {
// we get exception when the dictionary doesnt have the variable we wanted
// then it is an invalid expression
System.out.println("Invalid Expression : "+tokens[i]);
}
}
}
while (!opsStack.empty()) {
valueStack.push(performOperation(opsStack.pop(), valueStack.pop(), valueStack.pop()));
}
return valueStack.pop();
}

public static boolean isPrecedence(char op1, char op2) {
if (op2 == '(' || op2 == ')') {
return false;
}
return !((op1 == '/' || op1 == '*') && (op2 == '-' || op2 == '+'));
}
public static double performOperation(char op, double a, double b) {
switch (op) {
case '+':
return b + a;
case '-':
return b - a;
case '*':
return b * a;
case '/':
if (a == 0) {
throw new UnsupportedOperationException("Cannot divide by zero");
}
return b / a;
}
return 0.0;
}

private static boolean isOperator(char c) { // return true if c is an operator
return c == '+' || c == '-' || c == '*' || c == '/';
}

public static void main(String[] args) throws HashException {
// System.out.println("10.0 + 3 * 45.0 = " + EvaluateExpression.solveExpression("10.0 + 3 * 45.0"));
// System.out.println("100 * ( 2 + 12 ) = " + EvaluateExpression.solveExpression("100 * ( 2 + 12 )"));
// System.out.println("100 * ( 2 + 12 ) / 14 = " + EvaluateExpression.solveExpression("100 * ( 2 + 12 ) / 14"));

// Create a dictionary of variables a, b, c, and d
variables = new Dictionary(5);
variables.insert("anu", 10);
variables.insert("b", 17);
variables.insert("c", 20);
variables.insert("d", 13);

String expression = "anu * b + ( c / anu ) - d";
System.out.println(expression+" = "+EvaluateExpression.solveExpression(expression));

expression = "10 * 17 + ( 20 / 10 ) - 13";
System.out.println(expression+" = "+EvaluateExpression.solveExpression(expression));
}
}

Dictionary Class

public class Dictionary {
private final HashClass theDict[];
private final int size;
private int used;

public Dictionary(int maxSize) {
this.theDict = new HashClass[maxSize];
this.size = maxSize;
this.used = 0;
}
private int hash(String s) {
int retval = 0;
for(int i = 0; i < s.length(); i++)
{
retval += (int)s.charAt(i);
}
return retval % size;
}

public boolean isFull() {
return used >= size-1;
}

private int findWhere(String s) {// finds s or where it should be

int where = this.hash(s);
while (theDict[where] != null && !theDict[where].getKey().equals(s)) {
//System.out.println("Ouch");
where = (where + 1) % size;
}
return where;
}

public void delete(String s) throws HashException {
int where = findWhere(s);
if(theDict[where] != null) {
theDict[where] = null;
used--;
}
else {
throw new HashException("Missing Key" + s);
}
}

public double lookup(String s) throws HashException {
int where = findWhere(s);
if(theDict[where] != null)
return theDict[where].getValue();
else
throw new HashException("Missing Key" + s);
}

public void insert(String s, double val) throws HashException {
if(this.isFull()) {
throw new HashException("Hash table overflow");
}
int where = findWhere(s);
if (theDict[where] == null)
{
theDict[where] = new HashClass(s, val);
used++;
}
else
theDict[where].setValue(val);
}

@Override
public String toString() {
String retval = "";
for(int i = 0; i < size; i++)
{
if (theDict[i] != null)
retval += i + " " + theDict[i] + " ";
}
return retval;
}

public static void main(String args[]) throws Exception {
String words[] = {"cow", "aardvark", "axolotl", "hardware", "software", "tick", "waterbug", "tiger", "caribou", "dog", "clavicle", "patella", "appendix", "liver", "gizzard"};
Dictionary dict = new Dictionary(10);
for(int i = 0; i < words.length; i++)
{
dict.insert(words[i], i*2.5);
}
System.out.println(dict);
}
}

Hash Class:

public class HashClass {
private String key;
private double value;

public HashClass(String key, double value) {
this.key = key;
this.value = value;
}

public String getKey() {
return key;
}

public void setKey(String key) {
this.key = key;
}

public double getValue() {
return value;
}

public void setValue(double value) {
this.value = value;
}

}

Hash Exception class:

public class HashException extends Exception {
HashException(String string) {
super(string);
}
}

Editor Class:

import java.util.Scanner;
import java.util.StringTokenizer;
import java.io.*;
public class Editor {
private LLComp theText;
private String prompt;

static BufferedWriter bw = null;
static BufferedReader br = null;

private enum Keywords {
READ, SAVE, LIST, RESEQUENCE, QUIT, EXIT, UNDEFINED;
};

private Scanner console;

public Editor() {
this.theText = new LLComp();
this.prompt = ">";
this.console = new Scanner(System.in);
}

public String getPrompt() {

return "";
}

public void setPrompt(String p) {
}

private static boolean isInt(String s) // see if a string represents
{ // an integer.
boolean retval = false;
try {
Integer.parseInt(s);
retval = true;
} catch (NumberFormatException e) {
retval = false;
}
return retval;
}

public void process() {
boolean done = false;
String line;
while (!done) {
System.out.print(this.prompt);
line = console.nextLine().toUpperCase(); // Work only with upper case
String splitString[] = line.split(" ", 2);
// at this point, the line that was read in has been split into two
// arrays. splitString[0] contains the first token, splitString[1]
// contains all the rest of the line.

// At this point, you need to decide whether this is a command or
// a line of text to be entered.
if (this.isInt(splitString[0])) {
// Here we have a line of text to be entered. Write the code to
// insert it into the LLComp named theText.
theText.insertInOrder(line);
} else // otherwise, it is a command, so call doCommand to perform it.
done = this.doCommand(splitString[0]);
}
}

private boolean doCommand(String com) {
boolean retval = false;
Keywords command;
// This first bit takes the string in the first word of the line
// and turns it into one of the manifest constants of the
// enumerated data type. This makes it fairly easy to add new
// commands later.
try {
command = Keywords.valueOf(com);// command is a Keywords and can
} // can be used as the target of a switch.
catch (IllegalArgumentException e) {
command = Keywords.UNDEFINED; // An undefined Keywords will cause
} // an exception.
switch (command) {
case READ:
this.read();
break;
case SAVE:
this.save();
break;
case LIST:
this.list();
break;
case RESEQUENCE:
this.resequence();
break;
case QUIT:
System.exit(0);
break;
case EXIT:
retval = true;
break;
case UNDEFINED:
System.out.println("Undefined command:" + com);
}
return retval;
}

// You need to implement the following routines.

private void read() {

String textLine;
try {
while((textLine = br.readLine())!=null)
System.out.println(textLine);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

private void save() {
try {
bw.write(theText.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

private void list() {
System.out.println(theText);
}

private void resequence() {

String text = theText.toString();
String[] textL = text.split(" ");
System.out.println("Number of Lines" + textL.length);
if(textL.length < 10)
System.out.println("There is not more than 10 records");
else
{

for(int i = 9;i<textL.length;i++)
{
String[] stringText = textL[i].split(" " );
int number = Integer.parseInt(stringText[0]) + 10;
System.out.println(number +" " + stringText[1]);
}
}
}

public static void main(String args[]) {
Editor e = new Editor();
try {
bw = new BufferedWriter(new FileWriter("ProgramOutput.txt"));
br = new BufferedReader(new FileReader("ProgramOutput.txt"));
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
e.process();
}
}

LL (for editor):

public class LL<T>
{
private ListElement<T> head;
private ListElement<T> tail;

public LL()
{
this.head = new ListElement<T>();
this.tail = this.head;
}

public void insertHead(T val)
{
this.head.link = new ListElement<T>(val, this.head.link);
}

public void insertTail(T val)
{
this.tail.link = new ListElement<T>(val);
this.tail = this.tail.link;
}

public boolean isEmpty()
{
return this.head.link == null;
}

public T deleteHead() throws LLException
{
T retval = null;
if (this.isEmpty() )
throw new LLException("Attempt to delete from an empty list.");
else
{
retval = (T)this.head.link.value;
this.head.link = this.head.link.link;
if (this.isEmpty())
this.tail = this.head;
}
return retval;
}

public String toString()
{
String retval = "";
ListElement where = this.head;

while (where.link != null)
{
retval += where.link.value;
where = where.link;
}
return retval;
}

public static void main(String args[]) throws LLException
{
LL<Integer> myLL = new LL<Integer>();
}
}

class ListElement<R>
{
R value;
ListElement<R> link;

public ListElement(R v, ListElement<R> le)
{
this.value = v;
this.link = le;
}

public ListElement(R v)
{
this(v, null);
}

public ListElement()
{
this(null, null);
}
}

LL Comp (for Editor):

public class LLComp<T extends Comparable<? super T>>
{
private CListElement<T> head;
private CListElement<T> tail;

public LLComp()
{
this.head = new CListElement<T>();
this.tail = this.head;
}

public void insertInOrder(T val)
{
recInsInOrder(head, val);
}

private void recInsInOrder(CListElement<T> head, T val)
{
if (head.link == null)
{
head.link = new CListElement<T>(val);
}
else
{
if (head.link.value.compareTo(val) > 0)
{
head.link = new CListElement<T>(val, head.link);
}
else
{
recInsInOrder(head.link, val);
}
}
}

public void insertHead(T val)
{
this.head.link = new CListElement<T>(val, this.head.link);
}

public void insertTail(T val)
{
this.tail.link = new CListElement<T>(val);
this.tail = this.tail.link;
}

public boolean isEmpty()
{
return this.head.link == null;
}

while (where.link != null)
{
retval += where.link.value + " ";
where = where.link;
}
return retval;
}

public static void main(String args[])
{
LLComp<String> myLL = new LLComp<String>();

myLL.insertInOrder("xyzzy");
myLL.insertInOrder("lmnop");
myLL.insertInOrder("nope");
myLL.insertInOrder("zzzzz");

System.out.println(myLL);
}

}

class CListElement<R>
{
R value;
CListElement<R> link;

public CListElement(R v, CListElement<R> le)
{
this.value = v;
this.link = le;
}

public CListElement(R v)
{
this(v, null);
}

public CListElement()
{
this(null, null);
}
}

LL Exception:

public class LLException extends Exception
{
public LLException(String s)
{
super(s);
}
}

Explanation / Answer

import java.util.*;

public class EvaluateExpression {

for (int i = 0; i < tokens.length; i++) {
if(tokens[i] == ' ') continue; // if current character is a space, ignore it

if ( Character.isDigit(tokens[i])) { // if current character is a digit, then
StringBuilder sbuf = new StringBuilder(); // string builder is more faster than StringBuffer
while (i < tokens.length && (Character.isDigit(tokens[i]) || (tokens[i] == '.'))) {
sbuf.append(tokens[i++]);
}
valueStack.push(Double.parseDouble(sbuf.toString()));
} else if (tokens[i] == '(') {
opsStack.push(tokens[i]);
} else if (tokens[i] == ')') {
while (opsStack.peek() != '(') {
valueStack.push(performOperation(opsStack.pop(), valueStack.pop(), valueStack.pop()));
}
opsStack.pop();
} else if (isOperator(tokens[i])) { // if current character is an operator, then
while (!opsStack.empty() && isPrecedence(tokens[i], opsStack.peek())) {
valueStack.push(performOperation(opsStack.pop(), valueStack.pop(), valueStack.pop()));
}
opsStack.push(tokens[i]);
} else { // if it is neither a digit nor a operator, it might be a variable
try {
StringBuilder sbuf = new StringBuilder(); // string builder is more faster than StringBuffer
while (i < tokens.length && (Character.isAlphabetic(tokens[i]))) { // read all the characters of variable
sbuf.append(tokens[i++]); // read the characters of the variable
}
String varialbe = sbuf.toString(); // get the name of the variable
double val = variables.lookup(varialbe); // get the value of the expression

private static boolean isOperator(char c) { // return true if c is an operator
return c == '+' || c == '-' || c == '*' || c == '/';
}

public static void main(String[] args) throws HashException {
System.out.println("10.0 + 3 * 45.0 = " + EvaluateExpression.solveExpression("10.0 + 3 * 45.0"));
System.out.println("100 * ( 2 + 12 ) = " + EvaluateExpression.solveExpression("100 * ( 2 + 12 )"));
System.out.println("100 * ( 2 + 12 ) / 14 = " + EvaluateExpression.solveExpression("100 * ( 2 + 12 ) / 14"));

// Create a dictionary of variables a, b, c, and d
variables = new Dictionary(5);
variables.insert("anu", 10);
variables.insert("b", 17);
variables.insert("c", 20);
variables.insert("d", 13);

String expression = "anu * b + ( c / anu ) - d";
System.out.println(expression+" = "+EvaluateExpression.solveExpression(expression));

expression = "10 * 17 + ( 20 / 10 ) - 13";
System.out.println(expression+" = "+EvaluateExpression.solveExpression(expression));
}
}

Dictionary Class

public class Dictionary {
private final HashClass theDict[];
private final int size;
private int used;

public boolean isFull() {
return used >= size-1;
}

private int findWhere(String s) {// finds s or where it should be

int where = this.hash(s);
while (theDict[where] != null && !theDict[where].getKey().equals(s)) {
//System.out.println("Ouch");
where = (where + 1) % size;
}
return where;
}

public void delete(String s) throws HashException {
int where = findWhere(s);
if(theDict[where] != null) {
theDict[where] = null;
used--;
}
else {
throw new HashException("Missing Key" + s);
}
}

public double lookup(String s) throws HashException {
int where = findWhere(s);
if(theDict[where] != null)
return theDict[where].getValue();
else
throw new HashException("Missing Key" + s);
}

@Override
public String toString() {
String retval = "";
for(int i = 0; i < size; i++)
{
if (theDict[i] != null)
retval += i + " " + theDict[i] + " ";
}
return retval;
}

Hash Class:

public class HashClass {
private String key;
private double value;

public HashClass(String key, double value) {
this.key = key;
this.value = value;
}

public String getKey() {
return key;
}

public void setKey(String key) {
this.key = key;
}

public double getValue() {
return value;
}

public void setValue(double value) {
this.value = value;
}

}

Hash Exception class:

public class HashException extends Exception {
HashException(String string) {
super(string);
}
}
------------------------------------------------------------------
Editor Class:

import java.util.Scanner;
import java.util.StringTokenizer;
import java.io.*;
public class Editor {
private LLComp theText;
private String prompt;

static BufferedWriter bw = null;
static BufferedReader br = null;

private enum Keywords {
READ, SAVE, LIST, RESEQUENCE, QUIT, EXIT, UNDEFINED;
};

private Scanner console;

public Editor() {
this.theText = new LLComp();
this.prompt = ">";
this.console = new Scanner(System.in);
}

public String getPrompt() {

return "";
}

public void setPrompt(String p) {
}

if (this.isInt(splitString[0])) {
theText.insertInOrder(line);
} else // otherwise, it is a command, so call doCommand to perform it.
done = this.doCommand(splitString[0]);
}
}

private boolean doCommand(String com) {
boolean retval = false;
Keywords command;

try {
command = Keywords.valueOf(com);// command is a Keywords and can
} // can be used as the target of a switch.
catch (IllegalArgumentException e) {
command = Keywords.UNDEFINED; // An undefined Keywords will cause
} // an exception.
switch (command) {
case READ:
this.read();
break;
case SAVE:
this.save();
break;
case LIST:
this.list();
break;
case RESEQUENCE:
this.resequence();
break;
case QUIT:
System.exit(0);
break;
case EXIT:
retval = true;
break;
case UNDEFINED:
System.out.println("Undefined command:" + com);
}
return retval;
}

// You need to implement the following routines.

private void read() {

String textLine;
try {
while((textLine = br.readLine())!=null)
System.out.println(textLine);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

private void list() {
System.out.println(theText);
}

private void resequence() {

String text = theText.toString();
String[] textL = text.split(" ");
System.out.println("Number of Lines" + textL.length);
if(textL.length < 10)
System.out.println("There is not more than 10 records");
else
{

for(int i = 9;i {
String[] stringText = textL[i].split(" " );
int number = Integer.parseInt(stringText[0]) + 10;
System.out.println(number +" " + stringText[1]);
}
}
}

LL Comp (for Editor):

public class LLComp>
{
private CListElement head;
private CListElement tail;

public LLComp()
{
this.head = new CListElement();
this.tail = this.head;
}

public void insertInOrder(T val)
{
recInsInOrder(head, val);
}

private void recInsInOrder(CListElement head, T val)
{
if (head.link == null)
{
head.link = new CListElement(val);
}
else
{
if (head.link.value.compareTo(val) > 0)
{
head.link = new CListElement(val, head.link);
}
else
{
recInsInOrder(head.link, val);
}
}
}

public void insertHead(T val)
{
this.head.link = new CListElement(val, this.head.link);
}

public void insertTail(T val)
{
this.tail.link = new CListElement(val);
this.tail = this.tail.link;
}

public boolean isEmpty()
{
return this.head.link == null;
}

while (where.link != null)
{
retval += where.link.value + " ";
where = where.link;
}
return retval;
}

public static void main(String args[])
{
LLComp myLL = new LLComp();

myLL.insertInOrder("xyzzy");
myLL.insertInOrder("lmnop");
myLL.insertInOrder("nope");
myLL.insertInOrder("zzzzz");

System.out.println(myLL);
}

}

class CListElement
{
R value;
CListElement link;

public CListElement(R v, CListElement le)
{
this.value = v;
this.link = le;
}

public CListElement(R v)
{
this(v, null);
}

public CListElement()
{
this(null, null);
}
}
------------------------------------------------------------------
LL Exception:

public class LLException extends Exception
{
public LLException(String s)
{
super(s);
}
}

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