Java – Developing calculator without using any control statement?

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Hi Everybody!

I need to develop a basic calculator with only the basic functionalities i.e +,-,*,/ in java for my University assignment.

The restriction is that the calculator must be programmed without using any control statement e.g if, else, or any loop or switch statement.

Is there a possibility for taking input in the form of strings and then separating operand and operators in java?

I will be highly obliged in entertained.

Majida

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Answered By 0 points N/A #97432

Java – Developing calculator without using any control statement?

qa-featured

To develop a calculator without using any control statement

Type :

1. All JLabel components start with jlb*
2. All JPanel components start with jpl* 

3. All JMenu components start with jmenu* 
4. All JMenuItem components start with jmenuItem* 
5. All JDialog components start with jdlg* 
6. All JButton components start with jbn* */ import java.awt.BorderLayout; import java.awt.Color; import java.awt.Container; import java.awt.FlowLayout; import java.awt.Font; import java.awt.GridLayout; import java.awt.Window; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JButton; import javax.swing.JDialog; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.KeyStroke; public class Calculator extends JFrame implements ActionListener { 	// Variables 	final int MAX_INPUT_LENGTH = 20; 	final int INPUT_MODE = 0; 	final int RESULT_MODE = 1; 	final int ERROR_MODE = 2; 	int displayMode; 	boolean clearOnNextDigit, percent; 	double lastNumber; 	String lastOperator; 	private JMenu jmenuFile, jmenuHelp; 	private JMenuItem jmenuitemExit, jmenuitemAbout; 	private JLabel jlbOutput; 	private JButton jbnButtons[]; 	private JPanel jplMaster, jplBackSpace, jplControl; 	/* 	 * Font(String name, int style, int size) 	 Creates a new Font from the specified name, style and point size. 	 */ 	Font f12 = new Font("Times New Roman", 0, 12); 	Font f121 = new Font("Times New Roman", 1, 12); 	// Constructor 	public Calculator() { 		/* Set Up the JMenuBar. 		 * Have Provided All JMenu's with Mnemonics 		 * Have Provided some JMenuItem components with Keyboard Accelerators 		 */ 		jmenuFile = new JMenu("File"); 		jmenuFile.setFont(f121); 		jmenuFile.setMnemonic(KeyEvent.VK_F); 		jmenuitemExit = new JMenuItem("Exit"); 		jmenuitemExit.setFont(f12); 		jmenuitemExit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, 				ActionEvent.CTRL_MASK)); 		jmenuFile.add(jmenuitemExit); 		jmenuHelp = new JMenu("Help"); 		jmenuHelp.setFont(f121); 		jmenuHelp.setMnemonic(KeyEvent.VK_H); 		jmenuitemAbout = new JMenuItem("About Calculator"); 		jmenuitemAbout.setFont(f12); 		jmenuHelp.add(jmenuitemAbout); 		JMenuBar mb = new JMenuBar(); 		mb.add(jmenuFile); 		mb.add(jmenuHelp); 		setJMenuBar(mb); 		//Set frame layout manager 		setBackground(Color.gray); 		jplMaster = new JPanel(); 		jlbOutput = new JLabel("0"); 		jlbOutput.setHorizontalTextPosition(JLabel.RIGHT); 		jlbOutput.setBackground(Color.WHITE); 		jlbOutput.setOpaque(true); 		// Add components to frame 		getContentPane().add(jlbOutput, BorderLayout.NORTH); 		jbnButtons = new JButton[23]; 		//		GridLayout(int rows, int cols, int hgap, int vgap) 		JPanel jplButtons = new JPanel(); // container for Jbuttons 		// Create numeric Jbuttons 		for (int i = 0; i <= 9; i++) { 			// set each Jbutton label to the value of index 			jbnButtons[i] = new JButton(String.valueOf(i)); 		} 		// Create operator Jbuttons 		jbnButtons[10] = new JButton("+/-"); 		jbnButtons[11] = new JButton("."); 		jbnButtons[12] = new JButton("="); 		jbnButtons[13] = new JButton("/"); 		jbnButtons[14] = new JButton("*"); 		jbnButtons[15] = new JButton("-"); 		jbnButtons[16] = new JButton("+"); 		jbnButtons[17] = new JButton("sqrt"); 		jbnButtons[18] = new JButton("1/x"); 		jbnButtons[19] = new JButton("%"); 		jplBackSpace = new JPanel(); 		jplBackSpace.setLayout(new GridLayout(1, 1, 2, 2)); 		jbnButtons[20] = new JButton("Backspace"); 		jplBackSpace.add(jbnButtons[20]); 		jplControl = new JPanel(); 		jplControl.setLayout(new GridLayout(1, 2, 2, 2)); 		jbnButtons[21] = new JButton(" CE "); 		jbnButtons[22] = new JButton("C"); 		jplControl.add(jbnButtons[21]); 		jplControl.add(jbnButtons[22]); 		//		Setting all Numbered JButton's to Blue. The rest to Red 		for (int i = 0; i < jbnButtons.length; i++) { 			jbnButtons[i].setFont(f12); 			if (i < 10) 				jbnButtons[i].setForeground(Color.blue); 			else 				jbnButtons[i].setForeground(Color.red); 		} 		// Set panel layout manager for a 4 by 5 grid 		jplButtons.setLayout(new GridLayout(4, 5, 2, 2)); 		//Add buttons to keypad panel starting at top left 		// First row 		for (int i = 7; i <= 9; i++) { 			jplButtons.add(jbnButtons[i]); 		} 		// add button / and sqrt 		jplButtons.add(jbnButtons[13]); 		jplButtons.add(jbnButtons[17]); 		// Second row 		for (int i = 4; i <= 6; i++) { 			jplButtons.add(jbnButtons[i]); 		} 		// add button * and x^2 		jplButtons.add(jbnButtons[14]); 		jplButtons.add(jbnButtons[18]); 		// Third row 		for (int i = 1; i <= 3; i++) { 			jplButtons.add(jbnButtons[i]); 		} 		//adds button - and % 		jplButtons.add(jbnButtons[15]); 		jplButtons.add(jbnButtons[19]); 		//Fourth Row 		// add 0, +/-, ., +, and = 		jplButtons.add(jbnButtons[0]); 		jplButtons.add(jbnButtons[10]); 		jplButtons.add(jbnButtons[11]); 		jplButtons.add(jbnButtons[16]); 		jplButtons.add(jbnButtons[12]); 		jplMaster.setLayout(new BorderLayout()); 		jplMaster.add(jplBackSpace, BorderLayout.WEST); 		jplMaster.add(jplControl, BorderLayout.EAST); 		jplMaster.add(jplButtons, BorderLayout.SOUTH); 		// Add components to frame 		getContentPane().add(jplMaster, BorderLayout.SOUTH); 		requestFocus(); 		//activate ActionListener 		for (int i = 0; i < jbnButtons.length; i++) { 			jbnButtons[i].addActionListener(this); 		} 		jmenuitemAbout.addActionListener(this); 		jmenuitemExit.addActionListener(this); 		clearAll(); 		//add WindowListener for closing frame and ending program 		addWindowListener(new WindowAdapter() { 			public void windowClosed(WindowEvent e) { 				System.exit(0); 			} 		}); 	} //End of Contructor Calculator 	// Perform action public void actionPerformed(ActionEvent e){ 		double result = 0; 		if(e.getSource() == jmenuitemAbout){ 		 JDialog dlgAbout = new CustomABOUTDialog(this, 		"About Java Swing Calculator", true); 			dlgAbout.setVisible(true); 		}else if(e.getSource() == jmenuitemExit){ 			System.exit(0); 		}	 	// Search for the button pressed until end of array or key found 		for (int i=0; i< 1) 								setDisplayString("0"); 						} 						break; 					case 21:	// CE 						clearExisting(); 						break; 					case 22:	// C 						clearAll(); 						break; 				} 			} 		} 	}	void setDisplayString(String s) { 		jlbOutput.setText(s); 	} 	String getDisplayString() { 		return jlbOutput.getText(); 	} 	void addDigitToDisplay(int digit) { 		if (clearOnNextDigit) 			setDisplayString(""); 		String inputString = getDisplayString(); 		if (inputString.indexOf("0") == 0) { 			inputString = inputString.substring(1); 		} 		if ((!inputString.equals("0") || digit > 0) 				&& inputString.length() < MAX_INPUT_LENGTH) { 			setDisplayString(inputString + digit); 		} 		displayMode = INPUT_MODE; 		clearOnNextDigit = false; 	} 	void addDecimalPoint() { 		displayMode = INPUT_MODE; 		if (clearOnNextDigit) 			setDisplayString(""); 		String inputString = getDisplayString(); 		// If the input string already contains a decimal point, don't 		// do anything to it. 		if (inputString.indexOf(".") < 0) 			setDisplayString(new String(inputString + ".")); 	} 	void processSignChange() { 		if (displayMode == INPUT_MODE) { 			String input = getDisplayString(); 			if (input.length() > 0 && !input.equals("0")) { 				if (input.indexOf("-") == 0) 					setDisplayString(input.substring(1)); 				else 					setDisplayString("-" + input); 			} 		} else if (displayMode == RESULT_MODE) { 			double numberInDisplay = getNumberInDisplay(); 			if (numberInDisplay != 0) 				displayResult(-numberInDisplay); 		} 	} 	void clearAll() { 		setDisplayString("0"); 		lastOperator = "0"; 		lastNumber = 0; 		displayMode = INPUT_MODE; 		clearOnNextDigit = true; 	} 	void clearExisting() { 		setDisplayString("0"); 		clearOnNextDigit = true; 		displayMode = INPUT_MODE; 	} 	double getNumberInDisplay() { 		String input = jlbOutput.getText(); 		return Double.parseDouble(input); 	} 	void processOperator(String op) { 		if (displayMode != ERROR_MODE) { 			double numberInDisplay = getNumberInDisplay(); 			if (!lastOperator.equals("0")) { 				try { 					double result = processLastOperator(); 					displayResult(result); 					lastNumber = result; 				} catch (DivideByZeroException e) { 				} 			} else { 				lastNumber = numberInDisplay; 			} 			clearOnNextDigit = true; 			lastOperator = op; 		} 	} 	void processEquals() { 		double result = 0; 		if (displayMode != ERROR_MODE) { 			try { 				result = processLastOperator(); 				displayResult(result); 			} catch (DivideByZeroException e) { 				displayError("Cannot divide by zero!"); 			} 			lastOperator = "0"; 		} 	} 	double processLastOperator() throws DivideByZeroException { 		double result = 0; 		double numberInDisplay = getNumberInDisplay(); 		if (lastOperator.equals("/")) { 			if (numberInDisplay == 0) 				throw (new DivideByZeroException()); 			result = lastNumber / numberInDisplay; 		} 		if (lastOperator.equals("*")) 			result = lastNumber * numberInDisplay; 		if (lastOperator.equals("-")) 			result = lastNumber - numberInDisplay; 		if (lastOperator.equals("+")) 			result = lastNumber + numberInDisplay; 		return result; 	} 	void displayResult(double result) { 		setDisplayString(Double.toString(result)); 		lastNumber = result; 		displayMode = RESULT_MODE; 		clearOnNextDigit = true; 	} 	void displayError(String errorMessage) { 		setDisplayString(errorMessage); 		lastNumber = 0; 		displayMode = ERROR_MODE; 		clearOnNextDigit = true; 	} 	public static void main(String args[]) { 		Calculator calci = new Calculator(); 		Container contentPane = calci.getContentPane(); 		//		contentPane.setLayout(new BorderLayout()); 		calci.setTitle("Java Swing Calculator"); 		calci.setSize(241, 217); 		calci.pack(); 		calci.setLocation(400, 250); 		calci.setVisible(true); 		calci.setResizable(false); 	} } //End of Swing Calculator Class. class DivideByZeroException extends Exception { 	public DivideByZeroException() { 		super(); 	} 	public DivideByZeroException(String s) { 		super(s); 	} } class CustomABOUTDialog extends JDialog implements ActionListener { 	JButton jbnOk; 	CustomABOUTDialog(JFrame parent, String title, boolean modal) { 		super(parent, title, modal); 		setBackground(Color.black); 		JPanel p1 = new JPanel(new FlowLayout(FlowLayout.CENTER)); 		StringBuffer text = new StringBuffer(); 		text.append("Calculator Informationnn"); 		text.append("Developer:	Hemanthn"); 		text.append("Version:	1.0"); 		JTextArea jtAreaAbout = new JTextArea(5, 21); 		jtAreaAbout.setText(text.toString()); 		jtAreaAbout.setFont(new Font("Times New Roman", 1, 13)); 		jtAreaAbout.setEditable(false); 		p1.add(jtAreaAbout); 		p1.setBackground(Color.red); 		getContentPane().add(p1, BorderLayout.CENTER); 		JPanel p2 = new JPanel(new FlowLayout(FlowLayout.CENTER)); 		jbnOk = new JButton(" OK "); 		jbnOk.addActionListener(this); 		p2.add(jbnOk); 		getContentPane().add(p2, BorderLayout.SOUTH); 		setLocation(408, 270); 		setResizable(false); 		addWindowListener(new WindowAdapter() { 			public void windowClosing(WindowEvent e) { 				Window aboutDialog = e.getWindow(); 				aboutDialog.dispose(); 			} 		}); 		pack(); 	} 	public void actionPerformed(ActionEvent e) { 		if (e.getSource() == jbnOk) { 			this.dispose(); 		} 	} } 

 

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