Java/SWT JFace Eclipse/Calculator
Calculator by Michael Schmidt
<source lang="java">
/**
* Instances of this object class open a dialog with a simple calculator. * The calculator includes a memory register, Tooltips for the keys, and error * checking. It performs double precision calculations and includes square * root and inverse functions. Other computations can be added easily. * The code contains extensive comments. * This class can be called via an Action from the menu or toolbar. * Feel free to use this in your application! * * @author Michael Schmidt, 2006. */
//package mschmidt.komo; import org.eclipse.jface.dialogs.Dialog; import org.eclipse.jface.dialogs.IDialogConstants; import org.eclipse.swt.SWT; import org.eclipse.swt.events.SelectionAdapter; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.ruposite; import org.eclipse.swt.widgets.Control; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Label; import org.eclipse.swt.widgets.Shell; import org.eclipse.swt.widgets.Text; public class CalculatorMichaelSchmidt extends Dialog {
/*
* Initialize variables needed for this class.
*/
private Text displayText;
// The three calculator registers.
private String displayString = "0.";
private String memoryString = new String();
private String operatorString = new String();
// A variable to store the pending calculation
private char calcChar = " ";
// Error strings
private final String ERROR_STRING = "Error: ";
private final String NAN_STRING = "Not a Number";
private final String LONG_STRING = "Number too long";
private final String INFINITY_STRING = "Infinity";
// A flag to check if display should be cleared on the next keystroke
private boolean clearDisplay = true;
// An ID constant for the copy to clipboard key
private static final int CLIPBOARD_ID = IDialogConstants.NO_TO_ALL_ID + 1;
public static void main(String[] a){
new CalculatorMichaelSchmidt(new Shell(new Display()));
}
/*
* Standard constructor to create the dialog.
* @param parentShell the Dialog shell
*/
public CalculatorMichaelSchmidt(final Shell parentShell) {
super(parentShell);
}
/*
* Create contents of the dialog, a display at the top and the various
* buttons. The Tooltip for each button explains its function.
* @param parent the composite
* @return Control the controls
*/
@Override
protected Control createDialogArea(final Composite parent) {
Composite container = (Composite) super.createDialogArea(parent);
final GridLayout calculatorGridLayout = new GridLayout();
calculatorGridLayout.marginRight = 5;
calculatorGridLayout.marginLeft = 5;
calculatorGridLayout.marginBottom = 5;
calculatorGridLayout.marginTop = 5;
calculatorGridLayout.marginWidth = 10;
calculatorGridLayout.marginHeight = 2;
calculatorGridLayout.numColumns = 4;
calculatorGridLayout.verticalSpacing = 2;
calculatorGridLayout.makeColumnsEqualWidth = true;
calculatorGridLayout.horizontalSpacing = 2;
container.setLayout(calculatorGridLayout);
// The display. Note that it has a limit of 30 characters,
// much greater than the length of a double-precision number.
displayText = new Text(container, SWT.RIGHT | SWT.BORDER);
displayText.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));
displayText.setEditable(false);
displayText.setDoubleClickEnabled(false);
displayText.setTextLimit(30);
displayText.setText(displayString);
displayText.setLayoutData(new GridData(SWT.FILL, SWT.TOP, true, false, 4, 1));
final Button msButton = new Button(container, SWT.NONE);
msButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateMemory("S");
}
});
msButton.setToolTipText("Save value to Memory");
msButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
msButton.setText("MS");
final Button mcButton = new Button(container, SWT.NONE);
mcButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("D");
}
});
mcButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
mcButton.setToolTipText("Clear Memory");
mcButton.setText("MC");
final Button clearButton = new Button(container, SWT.NONE);
clearButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("C");
}
});
clearButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
clearButton.setToolTipText("Clear all Calculator Registers");
clearButton.setText("C");
final Button ceButton = new Button(container, SWT.NONE);
ceButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("E");
}
});
ceButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
ceButton.setToolTipText("Clear Entry");
ceButton.setText("CE");
final Button memAddButton = new Button(container, SWT.NONE);
memAddButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateMemory("+");
}
});
memAddButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
memAddButton.setToolTipText("Add value to Memory");
memAddButton.setText("M+");
final Button mrButton = new Button(container, SWT.NONE);
mrButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("R");
}
});
mrButton.setToolTipText("Recall value in Memory");
mrButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
mrButton.setText("MR");
final Button backButton = new Button(container, SWT.NONE);
backButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("B");
}
});
backButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
backButton.setToolTipText("Backspace");
backButton.setText("BACK");
final Button divideButton = new Button(container, SWT.NONE);
divideButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateCalc("/");
}
});
divideButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
divideButton.setToolTipText("Divide");
divideButton.setText("/");
final Button memSubtractButton = new Button(container, SWT.NONE);
memSubtractButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateMemory("-");
}
});
memSubtractButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
memSubtractButton.setToolTipText("Subtract value from Memory");
memSubtractButton.setText("M-");
final Button inverseButton = new Button(container, SWT.NONE);
inverseButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("I");
}
});
inverseButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
inverseButton.setToolTipText("Inverse of value");
inverseButton.setText("1/X");
final Button sqrtButton = new Button(container, SWT.NONE);
sqrtButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("Q");
}
});
sqrtButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
sqrtButton.setToolTipText("Square Root of value");
sqrtButton.setText("SQRT");
final Button multiplyButton = new Button(container, SWT.NONE);
multiplyButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateCalc("*");
}
});
multiplyButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
multiplyButton.setToolTipText("Multiply");
multiplyButton.setText("*");
final Button num7Button = new Button(container, SWT.NONE);
num7Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("7");
}
});
num7Button.setToolTipText("Numeric Pad");
num7Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num7Button.setText("7");
final Button num8Button = new Button(container, SWT.NONE);
num8Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("8");
}
});
num8Button.setToolTipText("Numeric Pad");
num8Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num8Button.setText("8");
final Button num9Button = new Button(container, SWT.NONE);
num9Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("9");
}
});
num9Button.setToolTipText("Numeric Pad");
num9Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num9Button.setText("9");
final Button SubtractButton = new Button(container, SWT.NONE);
SubtractButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateCalc("-");
}
});
SubtractButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
SubtractButton.setToolTipText("Subtract");
SubtractButton.setText("-");
final Button num4Button = new Button(container, SWT.NONE);
num4Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("4");
}
});
num4Button.setToolTipText("Numeric Pad");
num4Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num4Button.setText("4");
final Button num5Button = new Button(container, SWT.NONE);
num5Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("5");
}
});
num5Button.setToolTipText("Numeric Pad");
num5Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num5Button.setText("5");
final Button num6Button = new Button(container, SWT.NONE);
num6Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("6");
}
});
num6Button.setToolTipText("Numeric Pad");
num6Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num6Button.setText("6");
final Button AdditionButton = new Button(container, SWT.NONE);
AdditionButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateCalc("+");
}
});
AdditionButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
AdditionButton.setToolTipText("Add");
AdditionButton.setText("+");
final Button num1Button = new Button(container, SWT.NONE);
num1Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("1");
}
});
num1Button.setCapture(true);
num1Button.setToolTipText("Numeric Pad");
num1Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num1Button.setText("1");
final Button num2Button = new Button(container, SWT.NONE);
num2Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("2");
}
});
num2Button.setToolTipText("Numeric Pad");
num2Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num2Button.setText("2");
final Button num3Button = new Button(container, SWT.NONE);
num3Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("3");
}
});
num3Button.setToolTipText("Numeric Pad");
num3Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num3Button.setText("3");
final Button equalsButton = new Button(container, SWT.NONE);
equalsButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateCalc("=");
}
});
equalsButton.setToolTipText("Equals (get result)");
equalsButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false, 1, 2));
equalsButton.setText("=");
final Button num0Button = new Button(container, SWT.NONE);
num0Button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("0");
}
});
num0Button.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
num0Button.setToolTipText("Numeric Pad");
num0Button.setText("0");
final Button decimalButton = new Button(container, SWT.NONE);
decimalButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay(".");
}
});
decimalButton.setToolTipText("Numeric Pad");
decimalButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
decimalButton.setText(".");
final Button signButton = new Button(container, SWT.NONE);
signButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(final SelectionEvent e) {
updateDisplay("-");
}
});
signButton.setToolTipText("Change sign of value");
signButton.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, false));
signButton.setText("+/-");
new Label(container, SWT.NONE);
//
return container;
}
/*
* Create contents of the button bar, including a button to copy the
* display to the system clipboard and a close button.
* @param parent
*/
@Override
protected void createButtonsForButtonBar(final Composite parent) {
createButton(parent, CLIPBOARD_ID, "Copy to Clipboard", false);
createButton(parent, IDialogConstants.CANCEL_ID,
IDialogConstants.CLOSE_LABEL, true);
}
/*
* Set the initial size of the dialog.
*/
@Override
protected Point getInitialSize() {
return new Point(260, 350);
}
/*
* Standard method to configure the shell.
*/
protected void configureShell(final Shell newShell) {
super.configureShell(newShell);
newShell.setText("Calculator");
// Include code here to set the window icon. The line here is a sample using the
// Eclipse plugin getImageDescriptor convenience method.
// newShell.setImage(KomoPlugin.getImageDescriptor(ApplicationImages.CALCULATOR_ICON).createImage());
}
/*
* (non-Javadoc)
* Method that copies contents of the display window to the clipboard when
* the Copy to Clipboard button is clicked.
* @see org.eclipse.jface.dialogs.Dialog#buttonPressed(int)
*/
@Override
protected void buttonPressed(final int buttonID) {
if (buttonID == CLIPBOARD_ID) {
displayText.selectAll();
displayText.copy();
displayText.clearSelection();
} else {
super.buttonPressed(buttonID);
}
}
/*
* This method updates the display text based on user input.
*/
private void updateDisplay(final char keyPressed) {
char keyVal = keyPressed;
String tempString = new String();
boolean doClear = false;
if (!clearDisplay) {
tempString = displayString;
}
switch (keyVal) {
case "B": // Backspace
if (tempString.length() < 2) {
tempString = "";
} else {
tempString = tempString.substring(0, tempString.length() - 1);
}
break;
case "C": // Clear
tempString = "0.";
operatorString = "";
calcChar = " ";
doClear = true;
break;
case "D": // Clear Memory
memoryString = "";
break;
case "E": // Clear Entry
tempString = "0.";
doClear = true;
break;
case "I": // Inverse
tempString = doCalc(displayString, "", keyVal);
doClear = true;
break;
case "Q": // Square Root
tempString = doCalc(displayString, "", keyVal);
doClear = true;
break;
case "R": // Recall Memory to Display
tempString = memoryString;
doClear = true;
break;
case "-": // Change Sign
if (tempString.startsWith("-")) {
tempString = tempString.substring(1, tempString.length());
} else {
tempString = keyVal + tempString;
}
break;
case ".": // Can"t have two decimal points.
if (tempString.indexOf(".") == -1 && tempString.length() < 29) {
tempString = tempString + keyVal;
}
break;
case "0": // Don"t want 00 to be entered.
if (!tempString.equals("0") && tempString.length() < 29) {
tempString = tempString + keyVal;
}
break;
default: // Default case is for the digits 1 through 9.
if (tempString.length() < 29) {
tempString = tempString + keyVal;
}
break;
}
clearDisplay = doClear;
if (!displayString.equals(tempString)) {
displayString = tempString;
displayText.setText(displayString);
}
}
/*
* This method updates the value stored in memory.
* The value is cleared in the updateDisplay method.
*/
private void updateMemory(final char keyPressed) {
char keyVal = keyPressed;
String tempString = new String();
switch (keyVal) {
case "S": // Save to Memory
tempString = trimString(displayString);
break;
case "+": // Add to Memory
if (memoryString.length() == 0) {
tempString = trimString(displayString);
} else {
tempString = doCalc(memoryString, displayString, "+");
}
break;
case "-": // Subtract from Memory
if (memoryString.length() == 0) {
if (displayString.startsWith("-")) {
tempString = displayString.substring(1, displayString.length());
tempString = trimString(tempString);
} else if (displayString.equals("0.0")
|| displayString.equals("0")
|| displayString.equals("0.")
|| displayString.equals("-0.0")) {
tempString = "0";
} else {
tempString = keyVal + displayString;
tempString = trimString(displayString);
}
} else {
tempString = doCalc(memoryString, displayString, "-");
}
break;
default: // Do nothing - this should never happen.
break;
}
// Do not save invalid entries to memory.
if (tempString.startsWith(ERROR_STRING)) {
if (!displayString.equals(tempString)) {
displayString = tempString;
displayText.setText(displayString);
}
} else {
memoryString = tempString;
}
clearDisplay = true;
}
/*
* This method converts the operator and display strings to double values
* and performs the calculation.
*/
private String doCalc(final String valAString, final String valBString,
final char opChar) {
String resultString = ERROR_STRING + NAN_STRING;
Double valA = 0.0;
Double valB = 0.0;
Double valAnswer = 0.0;
// Make sure register strings are numbers
if (valAString.length() > 0) {
try {
valA = Double.parseDouble(valAString);
} catch (NumberFormatException e) {
return resultString;
}
} else {
return resultString;
}
if (opChar != "Q" && opChar != "I") {
if (valBString.length() > 0) {
try {
valB = Double.parseDouble(valBString);
} catch (NumberFormatException e) {
return resultString;
}
} else {
return resultString;
}
}
switch (opChar) {
case "Q": // Square Root
valAnswer = Math.sqrt(valA);
break;
case "I": // Inverse
valB = 1.0;
valAnswer = valB/valA;
break;
case "+": // Addition
valAnswer = valA + valB;
break;
case "-": // Subtraction
valAnswer = valA - valB;
break;
case "/": // Division
valAnswer = valA/valB;
break;
case "*": // Multiplication
valAnswer = valA*valB;
break;
default: // Do nothing - this should never happen
break;
}
// Convert answer to string and format it before return.
resultString = valAnswer.toString();
resultString = trimString(resultString);
return resultString;
}
/*
* This method updates the operator and display strings, and the
* pending calculation flag.
*/
private void updateCalc(char keyPressed) {
char keyVal = keyPressed;
String tempString = displayString;
/*
* If there is no display value, the keystroke is deemed invalid and
* nothing is done.
*/
if (tempString.length() == 0) {
return;
}
/*
* If there is no operator value, only calculation key presses are
* considered valid. Check that the display value is valid and
* if so, move the display value to the operator. No calculation is done.
*/
if (operatorString.length() == 0) {
if (keyVal != "=") {
tempString = trimString(tempString);
if (tempString.startsWith(ERROR_STRING)) {
clearDisplay = true;
operatorString = "";
calcChar = " ";
} else {
operatorString = tempString;
calcChar = keyVal;
clearDisplay = true;
}
}
return;
}
// There is an operator and a display value, so do the calculation.
displayString = doCalc(operatorString, tempString, calcChar);
/*
* If "=" was pressed or result was invalid, reset pending calculation
* flag and operator value. Otherwise, set new calculation flag so
* calculations can be chained.
*/
if (keyVal == "=" || displayString.startsWith(ERROR_STRING)) {
calcChar = " ";
operatorString = "";
} else {
calcChar = keyVal;
operatorString = displayString;
}
// Set the clear display flag and show the result.
clearDisplay = true;
displayText.setText(displayString);
}
/*
* This method formats a string.
*/
private String trimString(final String newString) {
String tempString = newString;
// Value is not a number
if (tempString.equals("NaN")) {
tempString = ERROR_STRING + NAN_STRING;
return tempString;
}
// Value is infinity
if (tempString.equals("Infinity") || tempString.equals("-Infinity")) {
tempString = ERROR_STRING + INFINITY_STRING;
return tempString;
}
// Value is -0
if (tempString.equals(-0.0)) {
tempString = "0";
return tempString;
}
// Trim unnecessary trailing .0
if (tempString.endsWith(".0")) {
tempString = tempString.substring(0, tempString.length() - 2);
}
// String is too long to display
if (tempString.length() > 28) {
tempString = ERROR_STRING + LONG_STRING;
}
return tempString;
}
}
</source>
Engine for Calculator by Michael Schmidt
<source lang="java">
/**
The following code is from Michael Schmidt(MichaelMSchmidt (at) msn.ru). The code is published under BSD license. Thanks for the input from Michael Schmidt.
- /
package us.mschmidt.komo; /**
* This is a generic calculator engine that includes a memory register, some * numeric conversions (square root, inverse), and the ability to chain * calculations. To use it, create a GUI shell with a display and some means * of entering keystrokes (Buttons work well). Invoke this engine from the GUI * shell using the constructor method, which requires that the display size * (String length) be set. Obtain the initial display, if desired, with the * getDisplayString() method. Subsequently, the display string is returned by * the setInput() method when an operation (character) is passed to the engine.*
* The constructor requires a display size to be set. The minimum is three * characters, with at least 22 characters recommended and recommended size * being 30 characters. * * @author Michael Schmidt * @version 1.1 */ class CalcEngine { // Instantiatee constants private final String calcChars; private final String convChars; private final String dispChars; private final String memChars; private final String errChars; // Instantiate variables // The error messages private String nanErr = new String(); private String tooLongErr = new String(); private String infinityErr = new String(); private int displaySize; // The calculator "registers" private String displayString = new String(); private String memoryString = new String(); private String operatorString = new String(); // A boolean to indicate if display will be cleared on the next key entry private boolean clearDisplay; // A character to store the pending calculation private char calcChar; /** * Constructor to create the calculator engine object. * * @param displaySizeVal The GUI display size, minimum of 3 and * recommended size of 30 */ CalcEngine(final int displaySizeVal) { final int minSize = 3; // Initialize operation characters calcChars = "+-/*="; convChars = "IQ"; dispChars = "BCERS.0123456789"; memChars = "DLMP"; errChars = "EINO*"; // Set initial display and internal variables displayString = "0."; clearDisplay = true; calcChar = " "; // Set the display size displaySize = minSize; if (displaySizeVal > minSize) { displaySize = displaySizeVal; } // Customize the error strings based on the display size setErrorStrings(); } /** * Customizes the error messages based on the display size. */ private void setErrorStrings() { // Initialize constants for display size thresholds final int infLength = 8; final int nanLength = 12; final int tooLongLength = 15; final int fullLength = 22; // Set default strings for optimal display size nanErr = "Not a Number"; tooLongErr = "Number too long"; infinityErr = "Infinity"; if (displaySize < infLength) { nanErr = "NaN"; tooLongErr = "***"; infinityErr = "Inf"; } else if (displaySize < nanLength) { nanErr = "NaN"; tooLongErr = "Overflow"; } else if (displaySize < tooLongLength) { tooLongErr = "Overflow"; } else if (displaySize >= fullLength) { nanErr = "ERROR: " + nanErr; tooLongErr = "ERROR: " + tooLongErr; infinityErr = "ERROR: " + infinityErr; } } /** * Provides the display string to the calling class. Used after the * engine is instantiated. Subsequently, the display string is returned by * the setInput() method. * * @return the display String */ public String getDisplayString() { return displayString; } /** * Allows entry of keystrokes from the calling class. * * @param keyVal A designation of the key pressed by the user using the * code. * Display codes: B backspace, C clear, E clear entry, * R recall memory to display, S change sign, . decimal, * 0-9 numeric entries. * Memory codes: D clear memory, M subtract from memory, * L store in memory, P add to memory. * Calculate codes: I inverse, Q square root, S subtract. * @return boolean true if the display has changed, false if not */ public String setInput(final char keyVal) { final char keyChar = keyVal; if (dispChars.indexOf(keyChar) != -1) { doDisplayOp(keyChar); } else if (convChars.indexOf(keyChar) != -1) { doConvertOp(keyChar); } else if (memChars.indexOf(keyChar) != -1) { doMemoryOp(keyChar); } else if (calcChars.indexOf(keyChar) != -1) { doCalcOp(keyChar); } return displayString; } /** * Clears the display when 1) the clearDisplay flag had previously been set * to "true" and 2) a new character or calculation operation is entered. */ private void doDisplayClear() { if (clearDisplay) { displayString = ""; clearDisplay = false; } } /** * Performs number conversion operations: inverse (1/X) and square root. * * @param keyVal a designation of the key pressed by the user */ private void doConvertOp(final char keyVal) { final char opChar = keyVal; String tempString = doConvert(displayString, opChar); clearDisplay = true; if (tempString.length() > 0) { displayString = tempString; } } /** * Performs display operations. Simple assignment operations are performed * in this method while more complex operations are performed in sub-methods. * * @param keyVal a designation of which key was pressed by the user */ private void doDisplayOp(final char keyVal) { final char opChar = keyVal; switch (opChar) { case "B": // Backspace doBackspace(); break; case "C": // Clear. Note use of dropthrough operatorString = ""; calcChar = " "; case "E": // Clear Entry displayString = "0."; clearDisplay = true; break; case "R": // Recall Memory to Display displayString = memoryString; break; case "S": // Change Sign doChangeSign(); break; case ".": // Can"t have two decimal points. doDecimal(opChar); break; case "0": // Don"t want 00 to be entered. doZero(opChar); break; default: // Default case is for the digits 1 through 9. doAddChar(opChar); break; } } /** * Performs backspace operation. */ private void doBackspace() { if (isError(displayString)) { return; } if (displayString.length() > 0) { displayString = displayString.substring( 0, displayString.length() - 1); } } /** * Performs operation to add a character to the display. * * @param c the character to add */ private void doAddChar(final char c) { if (isError(displayString)) { return; } if (displayString.length() < displaySize) { doDisplayClear(); displayString += c; } } /** * Performs sign change operation. */ private void doChangeSign() { if (isError(displayString)) { return; } if ("-" == displayString.charAt(0)) { displayString = displayString.substring( 1, displayString.length()); } else if (displayString.length() < displaySize) { displayString = "-" + displayString; } } /** * Performs operation when decimal is pressed. * * @param c the decimal character */ private void doDecimal(final char c) { if (isError(displayString)) { return; } if (displayString.indexOf(".") == -1 && displayString.length() < displaySize) { doDisplayClear(); displayString += c; } } /** * Performs operation when "0" is pressed. * * @param c the zero operation character */ private void doZero(final char c) { if (isError(displayString)) { return; } if (!displayString.equals("0") && displayString.length() < displaySize) { doDisplayClear(); displayString += c; } } /** * Updates the value stored in the memory register. Simple assignment * operations are performed here while more complex operations are performed * in sub-methods. * * @param keyVal a designation of which key was pressed by the user */ private void doMemoryOp(final char keyVal) { final char opChar = keyVal; switch (opChar) { case "D": // Clear Memory memoryString = ""; break; case "L": // Save to Memory assignMemoryString(trimString(displayString)); break; case "M": // Subtract from Memory subtractFromMemory(); break; case "P": // Add to Memory addToMemory(); break; default: // Do nothing - this should never happen. break; } clearDisplay = true; } /** * Performs the operation to add a display entry to the number in the * memory register. */ private void addToMemory() { String tempString = new String(); if (0 == memoryString.length()) { tempString = trimString(displayString); } else { tempString = doComputation(memoryString, displayString, "+"); } assignMemoryString(tempString); } /** * Performs the operation to subtract a display entry from the number in the * memory register. */ private void subtractFromMemory() { String tempString = new String(); if (0 == memoryString.length()) { tempString = doComputation("0", displayString, "-"); } else { tempString = doComputation(memoryString, displayString, "-"); } assignMemoryString(tempString); } /** * Checks if String is valid and, if so, assigns it to the memory register. * * @param s the String to assign */ private void assignMemoryString(final String s) { if (isError(s)) { displayString = s; } else { memoryString = s; } } /** * Guides 2-number calculations. Updates the operator string, display * string, and the pending calculation flag. Performs calculation if * possible. * * @param keyVal a designation of which key was pressed byt he user */ private void doCalcOp(final char keyVal) { final char opChar = keyVal; // If there is no display value, the keystroke is deemed invalid and // nothing is done. if (0 == displayString.length()) { return; } // If there is no operator value, "=" key presses are considered // invalid. If a calculation key is pressed, check that the display // value is valid and if so, copy the display value to the operator. // No calculation is done. if (0 == operatorString.length()) { if ("=" != opChar) { if (isError(displayString)) { calcChar = " "; } else { operatorString = displayString; calcChar = opChar; } clearDisplay = true; } return; } // There are operator and display values, so do the pending calculation. displayString = doComputation(operatorString, displayString, calcChar); // If "=" was pressed or result was invalid, reset pending calculation // flag and operator value. Otherwise, set new calculation flag so // calculations can be chained. if (("=" == opChar) || isError(displayString)) { calcChar = " "; operatorString = ""; } else { calcChar = opChar; operatorString = displayString; } // Set the clear display flag clearDisplay = true; } /** * Performs the computations. * * @param numStringA the displayed value * @param numStringB the stored value * @param opVal the operation to be performed * @return the solution as a string variable */ private String doComputation(final String numStringA, final String numStringB, final char opVal) { String valStringA = numStringA; String valStringB = numStringB; char opChar = opVal; Double valA = 0.0; Double valB = 0.0; Double valAnswer = 0.0; // Make sure register strings are numbers if (valStringA.length() > 0 && valStringB.length() > 0) { try { valA = Double.parseDouble(numStringA); valB = Double.parseDouble(numStringB); } catch (final NumberFormatException e) { return nanErr; } } else { return ""; } switch (opChar) { case "+": // Addition valAnswer = valA + valB; break; case "-": // Subtraction valAnswer = valA - valB; break; case "/": // Division valAnswer = valA / valB; break; case "*": // Multiplication valAnswer = valA * valB; break; default: // Do nothing - this should never happen break; } // Convert answer to properly formatted string. return trimString(valAnswer.toString()); } /** * Performs number conversion computations. * * @param numString the number to be converted * @param opVal designation of the operation to be performed * @return the converted value */ private String doConvert(final String numString, final char opVal) { char opChar = opVal; String valString = numString; Double valA = 0.0; Double valAnswer = 0.0; // Make sure String is a number. If it is zero-length, assume the // keystroke was inadvertent and return "". if (valString.length() > 0) { try { valA = Double.parseDouble(valString); } catch (final NumberFormatException e) { return nanErr; } } else { return ""; } switch (opChar) { case "Q": // Square Root valAnswer = Math.sqrt(valA); break; case "I": // Inverse valAnswer = 1.0 / valA; break; default: // Do nothing - this should never happen break; } // Return properly formatted result String. return trimString(valAnswer.toString()); } /** * Formats String to be displayed. * * @param stringVal a new string to be displayed * @return the properly formatted and trimmed string */ private String trimString(final String stringVal) { String returnString = stringVal; // Check if value is Not a Number if (returnString.equals("NaN")) { return nanErr; } // Check if value is infinity if (returnString.endsWith("Infinity")) { return infinityErr; } // Check if value is -0 if (returnString.equals("-0.0")) { return "0"; } // Trim unnecessary trailing .0 if (returnString.endsWith(".0")) { returnString = returnString.substring(0, returnString.length() - 2); } // Check if string is too long to display if (returnString.length() > displaySize) { return tooLongErr; } return returnString; } /** * Tests if the String is an error message. * * @param s the String to be tested * @return boolean true if this is an error message, false if not */ private boolean isError(final String s) { String testString = s; if (0 == testString.length()) { return false; } char c = testString.charAt(0); return ((errChars.indexOf(c) == -1)) ? false : true; } /** * Override to provide useful information when the class toString method is * called. * * @return the information String * @see java.lang.Object#toString() */ @Override public final String toString() { return "komo.CalcEngine is the engine portion of the calculator utility"; } } </source>
