Question

In Java. Please use the provided code

Required Items: 1. Create a new class and name it HwO6Source, and it contains the main method. In Hw06Source class, define an array of string and initialize it with following strings. "add 1.0" // Error: incorrect number of values add xx 25.0" // Error: non-numeric data "addx 0.0 0.0" // Error: invalid command "divide 100.0 50.0" "add 25.0 92.0" "subtract 225.0 17.0" "multiply 11.0 3.0" Create a new class, name it InvalidStatementException, and inherit it from Exception class. Implement two constructor for it as bellows: 1. Implement constructor with two string arguments, and name them reason and statement. Pass the argument to super class by concatenating the string values as reason + ": "+statement 2. Implement constructor with three arguments, and two of them are strings which their name shall be reason and statement, and the third argument type is Throwable which its name is cause. Pass the argument to super class by concatenating the string values as reason + ": "+statement. Throwable argument as the second argument to the super class.

Homework 5 Code:

public class Hw05Source {
public static void main(String[] args)
{
String[] equations ={"Divide 100.0 50.0",
"Add 25.0 92.0", "Subtract 225.0 17.0",
"Multiply 11.0 3.0"};
CalculateHelper helper= new CalculateHelper();
for (int i = 0;i {
helper.process(equations[i]);
helper.calculate();
System.out.println(helper);
}
}
}

//==========================================

public class MathEquation {
double leftValue;
double rightValue;
double result;
char opCode='a';

private MathEquation(){
}

public MathEquation(char opCode) {
this();
this.opCode = opCode;
}
public MathEquation(char opCode,double leftVal,double rightValue){
this(opCode);
this.leftValue=leftVal;
this.rightValue=rightValue;
}

public double getResult() {
return result;
}

void execute(int leftValue,int rightValue){
this.leftValue=leftValue;
this.rightValue=rightValue;
execute();
result=(int)result;
}
void execute(double leftValue,double rightValue){
this.leftValue=leftValue;
this.rightValue=rightValue;
execute();
}
void execute(){
switch (opCode){
case 'a':
result=leftValue+rightValue;
break;
case 's':
result=leftValue-rightValue;
break;
case 'm':
result=leftValue*rightValue;
break;
case 'd':
if(rightValue==0){
System.out.println("Error: right Value for division can be not zero!!!");
result = 0.0d;
break;
}
result=leftValue/rightValue;
break;
default:
System.out.println("Error: Invalid Operation Code");
result = 0.0d;
break;
}
}
}

//============================================

public abstract class CalculateBase {
private double leftValue;
private double rightValue;
private double result;

public double getLeftValue() {
return leftValue;
}

public void setLeftValue(double leftValue) {
this.leftValue = leftValue;
}

public double getRightValue() {
return rightValue;
}

public void setRightValue(double rightValue) {
this.rightValue = rightValue;
}

public double getResult() {
return result;
}

public void setResult(double result) {
this.result = result;
}

public CalculateBase() {
}

public CalculateBase(double leftValue, double rightValue) {
this();
this.leftValue = leftValue;
this.rightValue = rightValue;
}

public abstract void calculate();
}

//====================================

public class Adder extends CalculateBase{
public Adder() {
}

public Adder(double leftValue, double rightValue) {
super(leftValue, rightValue);
}

@Override
public void calculate() {
double value=getLeftValue()+getRightValue();
setResult(value);
}
}

//=====================================

public class Multiplier extends CalculateBase{
public Multiplier() {
}

public Multiplier(double leftValue, double rightValue) {
super(leftValue, rightValue);
}

@Override
public void calculate() {
double value=getLeftValue()*getRightValue();
setResult(value);
}
}

//===========================================

public class Subtractor extends CalculateBase {

public Subtractor() {
}
public Subtractor(double leftValue, double rightValue) {
super(leftValue, rightValue);
}
@Override
public void calculate() {
double value=getLeftValue()-getRightValue();
setResult(value);
}
}

//==============================

public class Divider extends CalculateBase {
public Divider() {
}

public Divider(double leftValue, double rightValue) {
super(leftValue, rightValue);
}

@Override
public void calculate() {
if(getRightValue()==0){
setResult(0);
return;
}
double value=getLeftValue()/getRightValue();
setResult(value);
}
}

//===========================================

public enum MathCommand {
Add, Subtract, Multiply, Divide;
}

//==========================================

public class CalculateHelper extends CalculateBase{
private double leftValue;
private double rightValue;
private double result;
MathCommand command;
public CalculateHelper()
{
leftValue =0;
rightValue=0;
result =0;
command = null;
}
public void process(String equation)
{
String[] tokens = equation.split(" ");
leftValue = Double.parseDouble(tokens[1]);
rightValue = Double.parseDouble(tokens[2]);
command = MathCommand.valueOf(tokens[0]);

}

@Override
public String toString() {
String result1 ="";
if(command==MathCommand.Add)
result1 = leftValue+" + "+rightValue+" = "+result;
if(command==MathCommand.Subtract)
result1 = leftValue+" - "+rightValue+" = "+result;
if(command==MathCommand.Multiply)
result1 = leftValue+" * "+rightValue+" = "+result;
if(command==MathCommand.Divide)
result1 = leftValue+" / "+rightValue+" = "+result;
return result1;
}

@Override
public void calculate() {

switch (command)
{
case Add:
Adder add = new Adder(leftValue,rightValue);
add.calculate();
result = add.getResult();
break;
case Subtract:
Subtractor subtractor = new Subtractor(leftValue,rightValue);
subtractor.calculate();
result = subtractor.getResult();
break;
case Multiply:
Multiplier multiplier = new Multiplier(leftValue,rightValue);
multiplier.calculate();
result = multiplier.getResult();
break;
case Divide:
Divider divider = new Divider(leftValue,rightValue);
divider.calculate();
result = divider.getResult();
break;
}
}
}

Answer 1

1.I have changed Hw05Source.java file completly

2.create new exception class InvalidStatementException.java

3.i have changed process method of CalculateHelper.java

Incorrect number of fields: Add 1.0 Non-numeric data: Add xx 25.0 Original exception: For input string: xx Invalid command: Addx 0.0 0.0 100.0 / 50.0 = 2.0 25.0 + 92.0 = 117.0 225.0 - 17.0 = 208.0 11.0 * 3.0 = 33.0

//Hw05Source.java
public class Hw05Source {
public static void main(String[] args) {
String[] equations = {
   "Add 1.0",
   "Add xx 25.0",
   "Addx 0.0 0.0",
"Divide 100.0 50.0",
"Add 25.0 92.0",
"Subtract 225.0 17.0",
"Multiply 11.0 3.0"
};
CalculateHelper helper = new CalculateHelper();
for (int i = 0; i < equations.length; i++){
       try{
helper.process(equations[i]);
helper.calculate();
System.out.println(helper);
       }catch(InvalidStatementException e){
           System.out.println(e.getMessage());
           if(e.getCause()!=null){
               System.out.println("\tOriginal exception: "+e.getCause().getMessage());
           }
       }
}
}
}

//process method of CalculateHelper.java

public void process(String equation) throws InvalidStatementException {
String[] tokens = equation.split(" ");
if(tokens.length!=3)
       throw new InvalidStatementException("Incorrect number of fields",equation);
if(!tokens[1].matches("-?\\d+(.\\d+)?")){
   throw new InvalidStatementException("Non-numeric data",equation,new Throwable("For input string: "+tokens[1]));
}
if(!tokens[2].matches("-?\\d+(.\\d+)?")){
   throw new InvalidStatementException("Non-numeric data",equation,new Throwable("For input string: "+tokens[2]));
}
if(!(tokens[0].equals("Add") || tokens[0].equals("Subtract") ||
   tokens[0].equals("Multiply") || tokens[0].equals("Divide"))){
   throw new InvalidStatementException("Invalid command",equation);
}
leftValue = Double.parseDouble(tokens[1]);
rightValue = Double.parseDouble(tokens[2]);
command = MathCommand.valueOf(tokens[0]);
}

InvalidStatementException.java

class InvalidStatementException extends Exception
{
public InvalidStatementException(String reason,String statement)
{
super(reason+": "+statement);
}
public InvalidStatementException(String reason,String statement,Throwable cause)
{
super(reason+": "+statement,cause);
}
}

////////////////////////////////////

Adder.java
CalculateBase.java
CalculateHelper.java
Divider.java
Hw05Source.java
InvalidStatementException.java
MathCommand.java
MathEquation.java
Multiplier.java
Subtractor.java

Explanation:

i have created user defined exception class InvlidStatementException.java which has 2 parametrized constructor which has both reason & statement another constructor with one more paramter throwable paramter

this below statement is to throw an exception when user forgot to enter two values for operations like Add 1.0

if(tokens.length!=3)
       throw new InvalidStatementException("Incorrect number of fields",equation);

this below statement is to throw an exception when user enter non numberic field for calculatoin operation

if(!tokens[1].matches("-?\\d+(.\\d+)?")){
   throw new InvalidStatementException("Non-numeric data",equation,new Throwable("For input string: "+tokens[1]));
}
if(!tokens[2].matches("-?\\d+(.\\d+)?")){
   throw new InvalidStatementException("Non-numeric data",equation,new Throwable("For input string: "+tokens[2]));
}

this below statement is to throw an exceptioon if the user enter invalid code for operation

if(!(tokens[0].equals("Add") || tokens[0].equals("Subtract") ||
   tokens[0].equals("Multiply") || tokens[0].equals("Divide"))){
   throw new InvalidStatementException("Invalid command",equation);
}