Question

Wanted advice and comments on A Java Calculator of making code better readable, Useable or coding tips what I could Change or keep.

HERE IS MY MAIN CLASS

package calculator;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

 /**
*
* @author abdimaden
*/
 public class Calculator extends JFrame implements ActionListener {

/**
 * @param args the command line arguments
 */
public static JTextField display;
JPanel displayPanel = new JPanel();
JButton numb;
JButton opButton;
boolean userIsInTheMiddleOfTyping;
CalculatorBrain brain = new CalculatorBrain();

@Override
public void setFont(Font font) {
    super.setFont(font);
}

public static void main(String[] args) {
    // TODO code application logic here

    Calculator calc = new Calculator();

}

public Calculator() {
    setLayout(new FlowLayout());
    setSize(500, 500);
    setTitle("Calculator: By Cabdifitaar Aden (CMProductions)");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);

    Layout();
    add(displayPanel);

    setVisible(true);
}

public void Layout() {

    displayPanel.setLayout(new GridBagLayout());

    GridBagConstraints c = new GridBagConstraints();

    //display

    display = new JTextField("0", SwingConstants.RIGHT);
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 0;
    c.gridwidth = 5;
    displayPanel.add(display, c);
    display.setFont(new Font("arial", Font.BOLD, 36));
    display.setEditable(false);
    display.setHorizontalAlignment(JTextField.RIGHT);
    display.setPreferredSize(new Dimension(500, 30));
    display.setBackground(Color.LIGHT_GRAY);
    //display.setHorizontalTextPosition(JLabel.RIGHT_ALIGNMENT);
    display.addActionListener(this);

    //operation buttons first row MC M+ M- MR
    opButton = new JButton("MC");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 1;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    opButton = new JButton("M+");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 1;
    c.gridy = 1;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    opButton = new JButton("M-");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 1;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    opButton = new JButton("MR");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 3;
    c.gridy = 1;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    //operation buttons second C +/- / *
    opButton = new JButton("C");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 2;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    opButton = new JButton("+/-");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 1;
    c.gridy = 2;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("specialOperation");

    opButton = new JButton("/");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 2;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("operation");

    opButton = new JButton("*");
    opButton.addActionListener(this);
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 3;
    c.gridy = 2;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.setActionCommand("operation");

    // buttons third row 7 8 9 -

    numb = new JButton("7");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 3;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("8");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 1;
    c.gridy = 3;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("9");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 3;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    opButton = new JButton("-");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 3;
    c.gridy = 3;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    // buttons third row 4 5 6 +
    opButton.setActionCommand("operation");

    numb = new JButton("4");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 4;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("5");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 1;
    c.gridy = 4;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("6");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 4;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    opButton = new JButton("+");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 3;
    c.gridy = 4;
    c.gridwidth = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("operation");
    // buttons third row 1 2 3 =

    numb = new JButton("1");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 5;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("2");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 1;
    c.gridy = 5;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    numb = new JButton("3");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 5;
    c.gridwidth = 1;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    opButton = new JButton("=");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 90;
    c.gridx = 3;
    c.gridy = 5;
    c.gridwidth = 1;
    c.gridheight = 3;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.addActionListener(this);
    opButton.setActionCommand("operation");

    /// last row 0 . 
    numb = new JButton("0");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 90;
    c.ipady = 30;
    c.gridx = 0;
    c.gridy = 6;
    c.gridwidth = 2;
    displayPanel.add(numb, c);
    numb.setFont(new Font("arial", Font.BOLD, 20));
    numb.addActionListener(this);
    numb.setActionCommand("digit");

    opButton = new JButton(".");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipadx = 30;
    c.ipady = 30;
    c.gridx = 2;
    c.gridy = 6;
    c.gridwidth = 1;
    c.gridheight = 1;
    displayPanel.add(opButton, c);
    opButton.setFont(new Font("arial", Font.BOLD, 20));
    opButton.setActionCommand("operation");
    // numb.addActionListener(this);
    //opButton.addActionListener(this);
}

@Override
public void actionPerformed(ActionEvent e) {
    // add your event handling code here

    // only the digit buttons will trigger the fallow if statment 
    if ("digit".equals(e.getActionCommand())) {
        //see which button trigged action    
        JButton digit = (JButton) e.getSource();
        //get the text from the button
        String digitPressed = digit.getText();
        if (userIsInTheMiddleOfTyping) {
            //display.setText(digitPressed);                    
            display.setText(display.getText() + digitPressed);
        } else {
            display.setText(digitPressed);
            userIsInTheMiddleOfTyping = true;
        }

    } else if ("operation".equals(e.getActionCommand())) {
        JButton button = (JButton) e.getSource();

        if (userIsInTheMiddleOfTyping) {
            //gets tricked when an operation button is pressed
            brain.setOperand(Integer.parseInt(display.getText()));
            userIsInTheMiddleOfTyping = false;

        }
        String operation = button.getText();

        double result = brain.perforumOperation(operation);
        String newResult = Double.toString(result);
        brain.formatDisplay(newResult);


    } else if ("specialOperation".equals(e.getActionCommand())) {
        //see which button trigged action    
        JButton specialOperationButton = (JButton) e.getSource();
        //get the text from the button
        String specialOperation = specialOperationButton.getText();

        brain.performSpecialOperation(specialOperation);
        userIsInTheMiddleOfTyping = false;

    }

}
 }

CALCULATOR BRAIN HERE IS WHERE ALL THE OPERATION AND CALCULATIONS HAPPEN

package calculator;

/**
*
* @author CMP
*/
import static javax.swing.JOptionPane.*;

public class CalculatorBrain {

//    Calculator calc = new Calculator();
double operAnd;
String waitingOperation;
double waitingOperand;
String plus = "+";
String specialOperation;
double memory = 0;

/// method to set the operAnd
public void setOperand(double anOperAnd) {
    operAnd = anOperAnd;

}

public void performWaitingOperation() {

    if (plus.equals(waitingOperation)) {

        operAnd = waitingOperand + operAnd;

    } else if ("-".equals(waitingOperation)) {

        operAnd = waitingOperand - operAnd;

    } else if ("/".equals(waitingOperation)) {
        String testFor0 = Double.toString(operAnd);
        if (testFor0.equals("0.0")) {
            showMessageDialog(null, "You can not divide by 0");
        } else {
            operAnd = waitingOperand / operAnd;
        }
    } else if ("*".equals(waitingOperation)) {

        operAnd = waitingOperand * operAnd;
    } else if ("C".equals(waitingOperation)) {
        operAnd = 0;
    }
}

public double perforumOperation(String operation) {
    if (operation.equals("sqrt")) {
    } else {
        performWaitingOperation();
        waitingOperation = operation;
        waitingOperand = operAnd;

    }

    return operAnd;

}

public void performSpecialOperation(String specialOp) {
    //specialOperation include C MC M+ M- MR +/-
    specialOperation = specialOp;

    //this if statement rests the screen and operAnd value to 0
    if ("C".equals(specialOperation)) {

        operAnd = 0;
        Calculator.display.setText("0");

    } else if ("+/-".equals(specialOperation)) {
        // this if stament checks whether the number is negative or positive

        if (operAnd < 0) {

            operAnd = Math.abs(operAnd);

        } else if (operAnd > 0) {

            operAnd = -operAnd;

        }

        String DisplayValue = Double.toString(operAnd);
        formatDisplay(DisplayValue);

    } else if ("MR".equals(specialOperation)) {

        String memoryValue = Double.toString(memory);

        formatDisplay(memoryValue);
    } else if ("M+".equals(specialOperation)) {

        memory = memory + Double.parseDouble(Calculator.display.getText());
        formatDisplay(Double.toString(memory));

    } else if ("MC".equals(specialOperation)) {

        memory = 0;
        formatDisplay(Double.toString(memory));

    } else if ("M-".equals(specialOperation)) {

        memory = memory - Double.parseDouble(Calculator.display.getText());
        formatDisplay(Double.toString(memory));

    }


}

public void formatDisplay(String value) {
    String newValue = value;
    if (value.endsWith(".0")) {
        newValue = value.substring(0, value.length() - 2);
        Calculator.display.setText("" + newValue);
    } else {
        Calculator.display.setText("" + newValue);
    }

}
}

IF YOU FIND THIS HELP FULL PLEASE COMMENT OF WHY
MANY THANKS JUST LOOKING FOR A WAY TO BECOME A BETTER PROGRAMMER AND GET THE RIGHT STYLE

Answer 1

I wouldn’t use StackOverflow for that (though I’m interested whether it will work 😉

I would rather use some plugins to make your code better readable, usable, robust, performant, correct … Suggested road-map:

• Install checkstyle to get acquainted with coding conventions and styles. Once you are familiar with it, rather soften the rules.
• Use Findbugs and PMD to find bugs, risky or performance-critical parts in your code.
• Start using metrics, e.g. about dependencies (e.g. jdepend), cyclomatic complexity (e.g.JavaNCSS) and test coverage (e.g. eclemma),
• Oh yes, and Write a lot of test cases (beforehand) for your code, e.g. to see how usable it is.

From here, you can go to

• continuous integration, e.g. using Jenkins together with Sonar.
• further agile practices to improve, especially using code reviews and pair programming
• get into clean code development (see Java tool to improve my Clean Code Development for support)