Java

[JaSS.lb]

Please some help to create a calculator on java netbeans program plz

[Tawa]

Here's one I made a year and a half ago as a Java Course project.

 import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator extends JFrame{ 
    private JTextField textfield;                    // The number Text Field.
    private JPanel superPanel;                        // The panel that contains all the other panels.
    private JPanel numberPanel;                        // The panel that contains the number buttons.
    private JPanel operatorPanel;                    // The panel that contains the operator buttons.
    private JMenuBar menuBar = new JMenuBar();        // The Calculator's Menu Bar.
    private JFrame helpFrame = new JFrame("Help");    // The help's Frame
    private JDialog errorDialog = new JDialog();    
    
    private ActionListener buttonListener = new ButtonListener();        // The listener for the Buttons others than numbers and operators.
    private ActionListener numberListener = new NumberListener();        // The listener for the Number Buttons.
    private    ActionListener operatorListener = new OperatorListener();    // The listener for the Operator Buttons.
    
    private boolean enteredFirstNumber = false;        // The boolean that tells the operation is a first number was entered to make an operation.
    private boolean enteredDot = false;                // The boolean that disables the user from adding more than a dot in a number.
    private String operator = "=";                    // The operator that controls the operations.
    private CalculatorOperation operation = new CalculatorOperation();        // The operation object/
    private final Font FONT = new Font("Comic Sans MS", Font.PLAIN, 25);    // The font for the calculator Frame/
    
    public Calculator(){
        /*
         * ADDING THE MENU BAR
         */
        JMenu fileMenu = new JMenu("File");                    // Creating a Menu with the name File.
        JMenuItem fileExitMenuItem = new JMenuItem("Exit");    // Creating the Exit button for the File Menu.
        fileExitMenuItem.addActionListener(buttonListener);    // Adding the listener.
        fileMenu.add(fileExitMenuItem);                        // Adding the Exit button to the File Menu.
        menuBar.add(fileMenu);                                // Adding the File Menu to the Menu Bar.
        
        JMenu editMenu = new JMenu("Edit");                        // Creating a Menu with the name Edit.
        JMenuItem editClearMenuItem = new JMenuItem();            // Creating the Clear button for the Edit Menu.
        editClearMenuItem.setName("C");                            // Setting The Name of the Button that will be used in the listener.
        editClearMenuItem.setText("Clear");                        // Setting The Text that is shown in the button.
        editClearMenuItem.addActionListener(operatorListener);    // Adding the Listener.
        editMenu.add(editClearMenuItem);                        // Adding the Clear Button to the Edit Menu.
                
        JMenuItem editEqualMenuItem = new JMenuItem();            // Creating the Equal button for the Edit Menu.
        editEqualMenuItem.setName("=");                            // Setting The Name of the Button that will be used in the listener.
        editEqualMenuItem.setText("Equals");                    // Setting The Text that is shown in the button.
        editEqualMenuItem.addActionListener(operatorListener);    // Adding the Listener.
        editMenu.add(editEqualMenuItem);                        // Adding the Equal Button to the Edit Menu.
        menuBar.add(editMenu);                                    // Adding the Edit Menu to the Menu Bar.

          JMenu helpMenu = new JMenu("Help");                                // Creating A Menu with the Name Help.
        JMenuItem helpHowToUseMenuItem = new JMenuItem("How To Use");    // Adding the How To Use Button for the Help Menu.
        helpHowToUseMenuItem.addActionListener(buttonListener);            // Adding The Listener.
        helpMenu.add(helpHowToUseMenuItem);                                // Adding the How To Use Button to the Help Menu.
        menuBar.add(helpMenu);                                            // Adding the Help Menu to the Menu Bar.
        
        /*
         * ADDING THE NUMBER BUTTONS TO THE NUMBER PANEL
         */
        String numberName = "1234567890. ";                // The Names of the number buttons in order.
        numberPanel = new JPanel(new GridLayout(4,4, 5,5));    // Creating the Panel of the Number Buttons
        for(int i = 0; i < numberName.length(); i++){
            String name = numberName.substring(i,i+1);        // Choosing the Name of the Button from the String.
            if(name.equals(" "))
                break;
            else{
                if(name.equals("0")){
                    JLabel label = new JLabel();
                    numberPanel.add(label);                    // Adding a Label before the 0 Button to make the Button appear in the Middle.
                }
                JButton button = new JButton(name);            // Creating the Button.
                button.setFont(FONT);                        // Setting the Font.
                button.addActionListener(numberListener);    // Adding the Listener.
                numberPanel.add(button);                    // Adding the Button to the Panel.
            }
        }
        
        /*
         * ADDING THE OPERATOR BUTTONS TO THE OPERATOR PANEL    // Same methodes used for the number panel are used in this Panel setting.
         */
        String operatorName = "+-*/C= ";
        operatorPanel = new JPanel(new GridLayout(4,4, 5,5));
        for(int i = 0; i < operatorName.length(); i++){
            String name = operatorName.substring(i,i+1);
            if(name.equals(" "))
                break;
            else{
                JButton button = new JButton(name);
                button.setFont(FONT);
                button.addActionListener(operatorListener);
                operatorPanel.add(button);
            }
        }

          /*
         * CREATING THE TEXT FIELD TO SHOW THE RESULTS AND CURRENT NUMBERS
         */
        textfield = new JTextField("0");                    // Creating the Textfield with the number 0.
        textfield.setFocusable(false);                        // Disabling the user from adding unrecognized digits (example: letters)
        textfield.setHorizontalAlignment(JTextField.RIGHT);    // Aligne to right in text field.
        textfield.setFont(FONT);                            // Setting the font.
        /*
         * ADDING SUBPANELS TO THE SUPER PANEL
         */
        superPanel = new JPanel(new BorderLayout(4,4));        // Creating a BorderLayout Panel with 4 pixels between the Contained Items
        superPanel.add(textfield, BorderLayout.NORTH);        // Adding the Textfield at the top of the Panel.
        superPanel.add(numberPanel, BorderLayout.WEST);        // Adding the Numberpanel at the left of the Panel.
        superPanel.add(operatorPanel, BorderLayout.EAST);    // Adding the Operatorpanel at the right of the Panel.

          /*
         * ADDING THE HELP FRAME
         */
        JButton okButton = new JButton("OK");        // This is the button that allows the user to close the help frame.
        JPanel okPanel = new JPanel();                // This is the panel that's gonna containe the OK Button
        okPanel.add(okButton);                        // Adding the ok button to the panel
        okButton.addActionListener(buttonListener);    // Adding the listener to the ok button
        
        JPanel helpPanel = new JPanel(new GridLayout(4,1,20,0));        // Creating the help panel with a GridLayout of 4 componants in a column with 20 pixels between them.

          // Adding the help text.
        helpPanel.add(new JLabel(" Use Number Panel To Enter Numbers"));
        helpPanel.add(new JLabel(" Use Operator Panel To Make Operations"));
        helpPanel.add(new JLabel(" Note: If You Press Enter, You Wont Be Able To Use The Result For A New Operation"));
        helpPanel.add(okPanel);

          helpFrame.setContentPane(helpPanel);    // Setting the Panel of the help frame.
        helpFrame.pack();
        helpFrame.setResizable(false);
        helpFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);    // Makes the help frame exists when a user closes it.
        
        /*
         * SETTING CONTENT PANE, MENU BAR, SIZE, AND TITLE.
         */
        setJMenuBar(menuBar);
        setContentPane(superPanel);
        setResizable(false);
        setTitle("Calculator");
        pack();
    }

      public void clear(){    // This Method Resets The Calculator
        enteredFirstNumber = false;
        enteredDot = false;
        operator = "=";
        textfield.setText("0");
        operation.setTotal("0");
    }

      /*
     * LISTENERS
     */
    public class OperatorListener implements ActionListener{
        public void actionPerformed(ActionEvent event){
            if(!enteredFirstNumber){        // The sentinel that makes the calculator start a new operation, and not to continue from an old result
                enteredFirstNumber = true;
                textfield.setText("0");
                operation.setTotal("0");
                operator = "=";
            }
            else{                            // Here the calculator makes the operations knowing that there are 2 numbers to affect the operation to.
                enteredFirstNumber = false;
                String display = textfield.getText();
                if(operator.equals("+")){
                    operation.add(display);
                }
                else if(operator.equals("-")){
                    operation.sub(display);
                }
                else if(operator.equals("*")){
                    operation.mul(display);
                }
                else if(operator.equals("/")){
                    try{
                        operation.div(display);
                    }
                    catch(DividingByZeroException e){
                        clear();
                    }
                }
                else if(operator.equals("=")){
                    operation.setTotal(display);
                }
                textfield.setText(operation.totalToString());    // Showing the result.
                operator = event.getActionCommand();            // Saving the operator for later operations.
                if(operator.equals("C")){                // Resetting the calculator.
                    clear();
                }
            }
        }
    }    
    
    public class NumberListener implements ActionListener{
        public void actionPerformed(ActionEvent event) {
            String key = event.getActionCommand();
            if(textfield.getText().length() >= 15){
                // To avoid entering a number larger than 15 digits.
            }
            else if(!enteredFirstNumber){         // To remove the leading Zero.
                if(key.equals(".")){
                    textfield.setText("0.");    // To wrote 0. instead of . when the first letter entered is a dot.
                    enteredDot = true;
                    enteredFirstNumber = true;
                }
                else if(key.equals("0")){
                    // To avoid entering a leading Zero.
                }
                else{
                    textfield.setText(key);
                    enteredFirstNumber = true;
                }
            }
            else if(key.equals(".") && !enteredDot){
                enteredDot = true;
                textfield.setText(textfield.getText()+key);            
            }
            else if(key.equals(".") && enteredDot){
                // to avoid entering more than a dot.
            }
            else
                textfield.setText(textfield.getText()+key);            
        }
    }
    public class ButtonListener implements ActionListener{
        public void actionPerformed(ActionEvent event){
            if(event.getActionCommand().equals("Exit")){
                dispose();                                    // This event closes the Calculator
            }
            else if(event.getActionCommand().equals("How To Use")){
                helpFrame.setVisible(true);                    // This event shows the Help Frame.
            }
            else if(event.getActionCommand().equals("OK")){    // This event closes the Help Frame.
                helpFrame.dispose();
            }
            else if(event.getActionCommand().equals("Ok")){    // This event closes the Error Dialog.
                errorDialog.dispose();
            }
        }
    }

      /*
     * OPERATIONS
     */
    public class CalculatorOperation{
        private double total;
        private double convertToNumber(String number){
            return Double.parseDouble(number);
        }

          public CalculatorOperation(){
            total = 0;
        }
        
        public void setTotal(String number){
                total = convertToNumber(number);
        }
        public void add(String number){
            total += convertToNumber(number);
        }
        public void sub(String number){
            total -= convertToNumber(number);
        }
        public void mul(String number){
            total *= convertToNumber(number);
        }
        public void div(String number)throws DividingByZeroException{
            if(convertToNumber(number)== 0){                // Throwing the exception.
                System.out.println("Engaging Exception");
                throw new DividingByZeroException();
            }
            total /= convertToNumber(number);
        }
        public String totalToString(){
            return "" + total;                // Returning the total under a String type instead of double.
        }
        
    }    
    /*
     * EXCEPTION
     */
    public class DividingByZeroException extends Exception{
        public DividingByZeroException(){
            // The exception creates a Dialog that tells the user that the calculator cannot divide by Zero.
            JPanel errorPanel = new JPanel(null);    // A null Layout means that we're gonna have to set the places and dimensions of all the componants
            JLabel errorLabel = new JLabel("Cannot Divide By Zero!");
            JButton okButton = new JButton("Ok");
            Font errorFont = new Font("Times New Roman", Font.BOLD, 15);

              errorLabel.setFont(errorFont);
            errorLabel.setBounds(40,0,260,50);
            errorPanel.add(errorLabel);
            
            errorPanel.add(okButton);
            okButton.addActionListener(buttonListener);
            okButton.setBounds(85, 40, 75,20);
            
            errorDialog.setContentPane(errorPanel);
            errorDialog.setSize(260,100);
            errorDialog.setAlwaysOnTop(true);
            errorDialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            errorDialog.setVisible(true);
            errorDialog.setResizable(false);
        }
    }

      /*
     * MAIN
     */
    public static void main(String arguments[]){
        JFrame c = new Calculator();
        c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        c.setVisible(true);    // Setting the calculator visible to the user
    }
}

[JaSS.lb]

thx alot tawa

[Tawa]

Originally Posted by JaSS.lb

thx alot tawa

The important thing is to learn how to do it, and not just copy it.

Anyway it's up to you.