Case Study: The ClockPane Class

package application;
import java.util.Calendar;
import java.util.GregorianCalendar;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.scene.text.Text;

public class ClockPane extends Pane {
    private int hour;
    private int minute;
    private int second;

    // Clock pane's width and height
    private double w = 250, h = 250;

    /** Construct a default clock with the current time */
    public ClockPane() {
        setCurrentTime();
    }

    /** Construct a clock with specified hour, minute, and second */
    public ClockPane(int hour, int minute, int second) {
        this.hour = hour;
        this.minute = minute;
        this.second = second;
        paintClock();
    }

    /** Return hour */
    public int getHour() {
        return hour;
    }

    /** Set a new hour */
    public void setHour(int hour) {
        this.hour = hour;
        paintClock();
    }

    /** return minute */
    public int getMinute() {
        return minute;
    }

    /** Set a new minute */
    public void setMinute(int minute) {
        this.minute = minute;
        paintClock();
    }

    /** Return second */
    public int getSecond() {
        return second;
    }

    /** Set a new second */
    public void setSecond(int second) {
        this.second = second;
        paintClock();
    }

    /** Return clock pane's width */
    public double getW() {
        return w;
    }

    /** Set clock pane's width */
    public void setW(double w) {
        this.w = w;
        paintClock();
    }

    /** Return clock pane's height */
    public double getH() {
        return h;
    }

    /** Set clock pane's height */
    public void setH(double h) {
        this.h = h;
        paintClock();
    }

    /** Set the current time for the clock */
    public void setCurrentTime() {
        // Construct a calendar for the current date and time
        Calendar calendar = new GregorianCalendar();

        // Set current hour, minute and second
        this.hour = calendar.get(Calendar.HOUR_OF_DAY);
        this.minute = calendar.get(Calendar.MINUTE);
        this.second = calendar.get(Calendar.SECOND);

        paintClock(); // Repaint the clock
    }

    /** Paint the clock */
    protected void paintClock() {
        // Initialize clock parameters
        double clockRadius = Math.min(w, h) * 0.8 * 0.5;
        double centerX = w / 2;
        double centerY = h / 2;

        // Draw circle
        Circle circle = new Circle(centerX, centerY, clockRadius);
        circle.setFill(Color.WHITE);
        circle.setStroke(Color.BLACK);
        Text t1 = new Text(centerX - 5, centerY - clockRadius + 12, "12");
        Text t2 = new Text(centerX - clockRadius + 3, centerY + 5, "9");
        Text t3 = new Text(centerX + clockRadius - 10, centerY + 3, "3");
        Text t4 = new Text(centerX - 3, centerY + clockRadius - 3, "6");

        // Draw second hand
        double sLength = clockRadius * 0.8;
        double secondX = centerX + sLength * Math.sin(second * (2 * Math.PI / 60));
        double secondY = centerY - sLength * Math.cos(second * (2 * Math.PI / 60));
        Line sLine = new Line(centerX, centerY, secondX, secondY);
        sLine.setStroke(Color.RED);

        // Draw minute hand
        double mLength = clockRadius * 0.65;
        double xMinute = centerX + mLength * Math.sin(minute * (2 * Math.PI / 60));
        double minuteY = centerY - mLength * Math.cos(minute * (2 * Math.PI / 60));
        Line mLine = new Line(centerX, centerY, xMinute, minuteY);
        mLine.setStroke(Color.BLUE);

        // Draw hour hand
        double hLength = clockRadius * 0.5;
        double hourX = centerX + hLength * Math.sin((hour % 12 + minute / 60.0) * (2 * Math.PI / 12));
        double hourY = centerY - hLength * Math.cos((hour % 12 + minute / 60.0) * (2 * Math.PI / 12));
        Line hLine = new Line(centerX, centerY, hourX, hourY);
        hLine.setStroke(Color.GREEN);

        getChildren().clear();
        getChildren().addAll(circle, t1, t2, t3, t4, sLine, mLine, hLine);
    }
}