public class SimpleCalculatorViewController implements ISimpleCalculatorViewController {
// ... constants
private static final String MINUS = "-";
private static final String ZERO = BigDecimal.ZERO.toString();
// ... configuration properties
final Locale locale = Locale.US;
final DecimalFormatSymbols symbols = new DecimalFormatSymbols(locale);
final String decimalSeparator = "" + symbols.getDecimalSeparator();
final String groupSeparator = "" + symbols.getGroupingSeparator();
// ... controller state properties
BigDecimal arg1;
String currentArgumentInput;
boolean currentArgumentInputFinished;
EMathOperation selectedOperation;
// ... constructor
public SimpleCalculatorViewController() {
init();
}
public void init() {
resetCurrentArgumentInput();
selectedOperation = null;
}
public SimpleCalculatorFacade getSimpleCalculatorFacade() {
final SimpleCalculatorFacade simpleCalculatorFacade = new SimpleCalculatorFacade();
return simpleCalculatorFacade;
}
// ... view data access
@Override
public String getDisplayValue() {
return currentArgumentInput;
}
@Override
public String getDecimalSeparator() {
return decimalSeparator;
}
// ... business methods
@Override
public void calculate() {
if (selectedOperation == null) {
// ... nothing to do: insufficient data for calculation.
} else {
final BigDecimal result;
final BigDecimal arg2 = BigDecimalUtils.stringToBigDecimal(currentArgumentInput, locale);
if (selectedOperation.isUnary()) {
result = getSimpleCalculatorFacade().calculate(arg2, selectedOperation);
} else {
result = getSimpleCalculatorFacade().calculate(arg1, arg2, selectedOperation);
}
selectedOperation = null;
currentArgumentInput = BigDecimalUtils.bigDecimalToString(result, locale);
currentArgumentInputFinished = true;
}
}
@Override
public void cancelInput() {
resetCurrentArgumentInput();
}
@Override
public void deleteLastInputSign() {
resetCurrentArgumentInput_If_It_Was_Finished();
final int currentArgumentLength = currentArgumentInput.length();
if (currentArgumentLength == 1) {
currentArgumentInput = ZERO;
}
if (currentArgumentLength == 2 && currentArgumentInput.startsWith(MINUS)) {
currentArgumentInput = ZERO;
}
if (currentArgumentLength > 1) {
currentArgumentInput = currentArgumentInput.substring(0, currentArgumentLength - 1);
}
}
@Override
public void putInCommaSign() {
resetCurrentArgumentInput_If_It_Was_Finished();
if (currentArgumentInput.contains(decimalSeparator)) {
// ... nothing to do: there is already a comma.
} else {
currentArgumentInput += decimalSeparator;
}
}
@Override
public void putInDigitSign(final byte number) {
resetCurrentArgumentInput_If_It_Was_Finished();
if (currentArgumentInput.equals(ZERO)) {
currentArgumentInput = "" + number;
} else {
currentArgumentInput += number;
}
}
private void resetCurrentArgumentInput() {
currentArgumentInput = ZERO;
currentArgumentInputFinished = false;
}
private void resetCurrentArgumentInput_If_It_Was_Finished() {
if (currentArgumentInputFinished) {
resetCurrentArgumentInput();
}
}
@Override
public void selectMathOperation(final EMathOperation mathOperation) {
selectedOperation = mathOperation;
arg1 = BigDecimalUtils.stringToBigDecimal(currentArgumentInput, locale);
currentArgumentInputFinished = true;
if (mathOperation.isUnary()) {
calculate();
}
}
}
