Java Calc (2of2)

//package calculator;

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

//Not public. Only accessible from within this folder.
class CalcGUI extends JFrame {

    //class variables and constants
    //use the same font for everything
    static Font displayFont = new Font("Arial", Font.PLAIN, 18);

    //instance objects inside GUI
    JButton bClr,bPlus,bMinus,bTimes,bDivide,bEquals,bSqr;
    JButton[] bDigit = new MyButton[10];
    JButton bp,bs;  //bp=button point, bs = button sign
    private JTextField display;
    MyActionListener myAL = new MyActionListener();
    MyKeyListener myKL = new MyKeyListener();

    // for testing only
    // public static void main(String args[]) {
        // new CalcGUI();
    // }


    CalcGUI() {             //constructor
        //set up everything to do with the JFrame here
        this.setSize(310,300);
        this.setTitle("Simple Calculator");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setDefaultLookAndFeelDecorated(true);
        this.setResizable(false);

        //use a contentPane in case I want to change the background
        Container content = this.getContentPane( );
        content.setLayout(new BorderLayout( ));


        //Make panels and components
        JPanel panelTop = new JPanel(); //defaults to flowlayout
        panelTop.setLayout(new FlowLayout(FlowLayout.CENTER,12,0)); //add some horizontal spacing
        panelTop.setBackground(new Color(249,249,179));
        display = new JTextField("0.0",16);
        display.setHorizontalAlignment(JTextField.RIGHT);
        display.setFont(displayFont);
        display.addKeyListener(myKL);
        panelTop.add(display);
        JButton bClr = new JButton("CE");   //this button is made separately. It needs smaller font.
        bClr.addActionListener(myAL);
        panelTop.add(bClr);
        //use borders for spacing.
        Border border0 = BorderFactory.createEmptyBorder(5,0,5,0);
        panelTop.setBorder(border0);
        content.add(panelTop, BorderLayout.NORTH);

        //set up number panel
        JPanel panelNum = new JPanel();
        panelNum.setLayout(new GridLayout(4,3,3,3));
        panelNum.setBackground(new Color(62,140,227));
        Border border = BorderFactory.createMatteBorder(5, 5, 2, 2, new Color(62,140,227));
        panelNum.setBorder(border);

        //create the digit buttons using an array.
        //The name of the buttons doesn't matter.
        //I'm basing my calcMain on the fact that each button will have a different first letter.
        for(int i=0;i<10;i++)
            bDigit[i] = new MyButton("" + i);
        panelNum.add(bDigit[7]);
        panelNum.add(bDigit[8]);
        panelNum.add(bDigit[9]);
        panelNum.add(bDigit[4]);
        panelNum.add(bDigit[5]);
        panelNum.add(bDigit[6]);
        panelNum.add(bDigit[1]);
        panelNum.add(bDigit[2]);
        panelNum.add(bDigit[3]);
        panelNum.add(bDigit[0]);
        JButton bp = new MyButton(".");
        JButton bs = new MyButton("\u00B1");    //Unicode +- character.
        panelNum.add(bp);
        panelNum.add(bs);
        content.add(panelNum, BorderLayout.CENTER);

        JPanel panelRight = new JPanel();
        panelRight.setLayout(new GridLayout(6,1,3,3));
        panelRight.setBackground(new Color(227,140,227));
        Border border2 = BorderFactory.createMatteBorder(9, 9, 7, 9, new Color(235,160,235));
        panelRight.setBorder(border2);

        JButton bSqr = new MyButton("\u221A");
        JButton bPlus = new MyButton("+");
        JButton bMinus = new MyButton("-");
        JButton bTimes = new MyButton("x");
        JButton bDivide = new MyButton("\u00F7");
        JButton bEquals = new MyButton("=");
        panelRight.add(bSqr);
        panelRight.add(bPlus);
        panelRight.add(bMinus);
        panelRight.add(bTimes);
        panelRight.add(bDivide);
        panelRight.add(bEquals);

        content.add(panelRight, BorderLayout.EAST);
        this.validate();
        this.setVisible(true);
    }

    //these two functions are called from CalcMain and are used to set the display.
    void setDisplay(String s){
        display.setText(s);
    }

    void setDisplay(Double d){
        display.setText(d.toString());
    }

    private class MyButton extends JButton{
        MyButton(String s) {
            super(s);       //create the JButton just like normal
            char c = (char)s.charAt(0);
            if (c >= '0' && c <= '9') this.setBackground(new Color(230,240,255));
            this.setFont(displayFont);
            this.addActionListener(myAL);   //all buttons can use the same action listener.
        }
    }

    private class MyActionListener implements ActionListener {
        public void actionPerformed( ActionEvent e ) {
            String txt = e.getActionCommand();
            CalcMain.sendButton(txt);   //Here's the important part.
        }
    }

    private class MyKeyListener implements KeyListener {
        public void keyTyped( KeyEvent e ) {
            String txt ="";
            // Keyboard code for the pressed key.
            // int key = e.getKeyCode();
            char key = e.getKeyChar();
            switch (key) {
                case '\n':  //Enter = '='
                    txt="=";
                    break;
                case '\b':  //backspace = CE
                    txt="C";
                    break;
                case '/':
                    txt="\u00F7";
                    break;
                case '*':
                    txt="x";
                    break;
                case 'q':
                    txt="\u221A";
                    break;
                default:
                    txt= Character.toString(key);
            }
            e.consume();    //after it updates the display, the keypressed also is displayed. Must consume it!!!

            CalcMain.sendButton(txt);

        }
        public void keyReleased( KeyEvent e ) {}
        public void keyPressed( KeyEvent e ) {}
    }
}