I was doing a simple exercise to calculate the amount based on an expression.
For example:
(((2*2)+(3*5/5)+(2*5))) outputs 17
((2*2)(3*5/5)(2*5)) output 120 etc
I have written the code, but I am not satisfied with what I've done. Could you please help me to review the code and suggest the best approach for that?
import java.util.ArrayList;
public class Calculator {
private static ArrayList<String> data;
private static Element element = new Element();
int startIndex = 0;
int endIndex = 0;
public int length = 0;
boolean startFlag = false;
public double calculatedValue = 0;
public Calculator() {
// TODO Auto-generated constructor stub
}
public static void main(String[] args) {
// String testExpression = "(((2*2)+(3*5/5)+(2*5)))";//17
String testExpression = "((2*2)(3*5/5)(2*5))"; // 120--
new Calculator().parsedExpression(testExpression);
}
public void parsedExpression(String testExpression) {
System.out.println(testExpression + " Before formatting");
testExpression = testExpression.replaceAll("\\)\\(", ")*("); // To
// change
// (a+b)(b+c)
// to
// (a+b)*(b+c)
System.out.println(testExpression + " After first formatting");
data = CalculatorUtil.parseExpression(testExpression);
System.out.println("Total Sum====" + process());
}
public double process() {
System.out.println("Array:ist" + data);
startIndex = 0;
endIndex = 0;
length = data.size();
System.out.println("===" + data.indexOf("("));
if (data.indexOf("(") >= 0) {
getCalIndex();
System.out.println("startIndex=" + startIndex + "==" + endIndex);
}
if (startIndex < endIndex) {
double value = calculate(startIndex, endIndex);
calculatedValue = value;
System.out.println("CalculatedValue=" + value);
// Reset arrayList
if (startIndex >= 0 || endIndex <= length) {
// Resize the list
ArrayList<String> tempList = new ArrayList<>();
int j = 0;
for (int i = 0; i < startIndex - 1; i++) {
tempList.add(data.get(i));
}
tempList.add(value + "");
for (int i = endIndex; i < length; i++) {
tempList.add(data.get(i));
}
data = tempList;
process();
}
}
return calculatedValue;
}
private void getCalIndex() {
endIndex = 0;
startIndex = 0;
for (String element : data) {
endIndex++;
startIndex++;
if (element.equals(")")) {
for (int i = endIndex - 1; i >= 0; i--) {
if (data.get(i).equals("(")) {
return;
}
startIndex--;
}
}
}
}
public double calculate(int startIndex, int endIndex) {
int j = 0;
element = new Element();
for (int i = startIndex; i < endIndex; i++) {
switch (data.get(i)) {
case "*" :
addOrManipulateEntitySecond('*', i, j);
break;
case "/" :
addOrManipulateEntitySecond('/', i, j);
break;
case "-" :
addOrManipulateEntityFirst('-', i, j);
break;
case "+" :
addOrManipulateEntityFirst('+', i, j);
break;
default :
break;
}
}
/** Printing the Elements **/
double operateCalculate = operate(element.getFirst(),
element.getOperator(), element.getSecond());
System.out.println("OperateCacluate=" + startIndex + "=" + endIndex
+ "=" + operateCalculate);
return operateCalculate;
}
private static void addOrManipulateEntityFirst(char o, int i, int j) {
if (element.getOperator() == '\u0000') {
element = new Element(Double.valueOf(data.get(i - 1)),
Double.valueOf(data.get(i + 1)), o);
} else {
element.setFirst(element.operate());
element.setSecond(Double.valueOf(data.get(i + 1)));
element.setOperator(o);
}
}
private void addOrManipulateEntitySecond(char o, int i, int j) {
if (element.getOperator() == '\u0000') {
element = new Element(Double.valueOf(data.get(i - 1)),
Double.valueOf(data.get(i + 1)), o);
} else {
element.setSecond(operate(element.getSecond(), o,
Double.valueOf(data.get(i + 1))));
// elements[j].setFirst(Double.valueOf(data.get(i+1)));
// elements[j].setOperator(o);
}
}
private double operate(double first, char o, double second) {
double result = 0;
switch (o) {
case '*' :
result = first * second;
break;
case '/' :
result = first / second;
break;
case '+' :
result = first + second;
break;
case '-' :
result = first - second;
break;
default :
break;
}
if (result == 0) {
result = calculatedValue;
}
return result;
}
}
public class Element {
private double first;
private double second;
private char operator;
private double result;
public Element() {
}
public Element(double first, double second, char operator) {
this.first = first;
this.second = second;
this.operator = operator;
System.out.println(this);
}
public double operate() {
switch (operator) {
case '*' :
result = first * second;
break;
case '/' :
result = first / second;
break;
case '+' :
result = first + second;
break;
default :
break;
}
return result;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "[ " + first + " " + operator + " " + second + " ]";
}
public double getFirst() {
return first;
}
public void setFirst(double first) {
System.out.println("First : " + first);
this.first = first;
}
public double getSecond() {
return second;
}
public void setSecond(double second) {
this.second = second;
}
public char getOperator() {
return operator;
}
public void setOperator(char operator) {
this.operator = operator;
}
public double getResult() {
return result;
}
public void setResult(double result) {
this.result = result;
}
}
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class CalculatorUtil {
public static final String INTEGER_FROM_STRING = "\\d+";
public static final String FLOAT_FROM_STRING = "(\\d+[.]\\d+)";
public static final String OPERATORS_FROM_STRING = "(\\/)|(\\-)|(\\+)|(\\*)|(\\%)|(\\()|(\\))|(\\^)";
public static final String NUMBERS_FROM_STRING = FLOAT_FROM_STRING+"|"+INTEGER_FROM_STRING;
public static final String NUMBERS_AND_OPERATORS_FROM_STRING = NUMBERS_FROM_STRING+"|"+OPERATORS_FROM_STRING;
public static final String MULTIPLICATION_COMMON = "\\)\\(";
public static final String MULTIPLICATION_VALID = ")*(";
private static Pattern pattern;
private static Matcher matcher;
public CalculatorUtil() {
// TODO Auto-generated constructor stub
}
/**
*
* @param input
* @return The data as ArrayList<String>
*/
public static ArrayList<String> parseExpression(String input)
{
pattern = Pattern.compile(NUMBERS_AND_OPERATORS_FROM_STRING);
matcher = pattern.matcher(input);
ArrayList<String> data = new ArrayList<String>();
while(matcher.find()) data.add(matcher.group());
return data;
}
}
