how can you make a progress bar without using JProgressBar?

Question

i am looking at putting a progress bar into a game i am making with a count down from a random number between 5 and 20 down to 0. this is my code so far:

package Software;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.Timer;

public class CountDownProgressBar extends JPanel {

    RandomValues randomNum;
    int timeValue;
    Timer timer;
    int length, newLength;

    public CountDownProgressBar() {
        timer = new Timer(24, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
               for (int i = timeValue; i > 0; --i) {
                        newLength = length - (length / timeValue);
                        length = newLength;
                        repaint();
                    }
                }
            });
        randomNum = new RandomValues();
        this.timeValue = 0;
        this.setBackground(Color.GRAY);
    }

    @Override
    public void paint(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.green);
        g.fillRect(0, 0, length, 50);
    }

    public void setTimeLength() {
        this.timeValue = randomNum.integer(5, 20);
    }

    public int getTimeLength() {
        return this.timeValue;
    }
}

I know most of it is wrong, i just cant figure out how to do. it needs to not use JProgressBar, instead use graphics (a green rectangle) where it gets smaller and smaller and the time counts down. and how would I make it so the screen can be resizable and the bar will still count down relative to the screen size. so it isnt jsut one fixed size but just goes across the bottom of the screen.

Answer 1

This is the code of a custom JProgressBar I made long time ago (I know the question states to not use a JProgressBar but you can grab code ideas from it), it was designed to resemble the progress bar look & feel from the "Human" theme in ubuntu 9.04:

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Composite;
import java.awt.FontMetrics;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JProgressBar;

/**
 * A progressBar that looks like the progress bar from Ubuntu 9.04 Human Theme
 */
public class HumanProgressBar extends JProgressBar {
    private static final long serialVersionUID = 1L;

    private static final String DISABLED_PERCENT_STRING = " --- ";

    private static final Color gradientEndingColor = new Color(0xc0c0c0);
    private static final Color borderColor = new Color(0x736a60);
    private static final Color disabledBorderColor = new Color(0xbebebe);    

    private static final Composite transparent = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.45f);
    private static final Composite veryTransparent = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.25f);

    private static GradientPaint gradient;

    private int oldWidth;
    private int oldHeight;

    private int displayWidth;
    private int displayHeight;

    private int insets[] = new int[4];
    private static final int TOP_INSET = 0;
    private static final int LEFT_INSET = 1;
    private static final int BOTTOM_INSET = 2;
    private static final int RIGHT_INSET = 3;

    private static final int PREFERRED_PERCENT_STRING_MARGIN_WIDTH = 3;

    public static final Color PREFERRED_PROGRESS_COLOR = new Color(0x1869A6);

    private boolean percentStringVisible = true;

    private Color progressColor;

    private String maxPercentString;

    public HumanProgressBar() {
        progressColor = PREFERRED_PROGRESS_COLOR;
    }

    public void updateGraphics() {
        update(getGraphics());
    }

    @Override
    protected void paintComponent(Graphics g) {
        int w = displayWidth != 0 ? displayWidth - 1 : getWidth() - 1;
        int h = displayHeight != 0 ? displayHeight - 1 : getHeight() - 1;

        int x = insets[LEFT_INSET];
        int y = insets[TOP_INSET];
        w -= (insets[RIGHT_INSET] << 1);
        h -= (insets[BOTTOM_INSET] << 1);

        if (gradient == null) {
            gradient = new GradientPaint(0.0f, 0.0f, Color.WHITE, 0.0f, h, gradientEndingColor);
        }
        Graphics2D g2d = (Graphics2D) g;
        // Clean background
        if (isOpaque()) {
            g2d.setColor(getBackground());
            g2d.fillRect(0, 0, getWidth(), getHeight());
        }

        g2d.translate(x, y);

        if (percentStringVisible) {
            FontMetrics fm = g.getFontMetrics();
            int stringW = 0;
            int stringH = 0;

            g2d.setColor(getForeground());

            if (isEnabled()) { 
                int p = getValue();
                String percent = Integer.toString(p, 10) + "%";
                if (p < 10) {
                    percent = "0" + percent;
                }

                if (maxPercentString == null) {
                    maxPercentString = Integer.toString(getMaximum(), 10) + "%";
                }
                stringW = fm.stringWidth(maxPercentString);
                stringH = ((h - fm.getHeight()) / 2) + fm.getAscent();

                g2d.drawString(percent, w - stringW, stringH);
            } else {
                stringW = fm.stringWidth(DISABLED_PERCENT_STRING);
                stringH = ((h - fm.getHeight()) / 2) + fm.getAscent();

                g2d.drawString(DISABLED_PERCENT_STRING, w - stringW, stringH);
            }
            w -= (stringW + PREFERRED_PERCENT_STRING_MARGIN_WIDTH);            
        }

        // Control Border
        g2d.setColor(isEnabled() ? borderColor : disabledBorderColor);
        g2d.drawLine(1, 0, w - 1, 0);
        g2d.drawLine(1, h, w - 1, h);
        g2d.drawLine(0, 1, 0, h - 1);
        g2d.drawLine(w, 1, w, h - 1);

        // Fill in the progress
        int min = getMinimum();
        int max = getMaximum();
        int total = max - min;
        float dx = (float) (w - 2) / (float) total;
        int value = getValue();
        int progress = 0; 
        if (value == max) {
            progress = w - 1;
        } else {
            progress = (int) (dx * getValue());            
        }

        g2d.setColor(progressColor);
        g2d.fillRect(1, 1, progress, h - 1);

        // A gradient over the progress fill
        g2d.setPaint(gradient);
        g2d.setComposite(transparent);
        g2d.fillRect(1, 1, w - 1, (h >> 1));
        final float FACTOR = 0.20f;
        g2d.fillRect(1, h - (int) (h * FACTOR), w - 1, (int) (h * FACTOR));

        if (isEnabled()) {
            for (int i = h; i < w; i += h) {
                g2d.setComposite(veryTransparent);
                g2d.setColor(Color.GRAY);
                g2d.drawLine(i, 1, i, h - 1);
                g2d.setColor(Color.WHITE);
                g2d.drawLine(i + 1, 1, i + 1, h - 1);
            }
        } else {
            for (int i = 0; i < w; i += h) {
                g2d.setComposite(veryTransparent);
                g2d.setColor(Color.RED);
                g2d.drawLine(i, h - 1, i + h, 1);
                g2d.setColor(Color.WHITE);
                g2d.drawLine(i + 1, h - 1, i + 1 + h, 1);
            }            
        }
    }

    public void setInsets(int top, int left, int bottom, int right) {
        insets[TOP_INSET] = top;
        insets[LEFT_INSET] = left;
        insets[BOTTOM_INSET] = bottom;
        insets[RIGHT_INSET] = right;
    }

    public void setPercentStringVisible(boolean percentStringVisible) {
        this.percentStringVisible = percentStringVisible;
    }

    @Override
    protected void paintBorder(Graphics g) {
    }

    @Override
    public void validate() {
        int w = getWidth();
        int h = getHeight();

        super.validate();
        if (oldWidth != w || oldHeight != h) {
            oldWidth = w;
            oldHeight = h;
            gradient = null;
        }
    }

    @Override
    public void setMaximum(int n) {
        super.setMaximum(n);
        maxPercentString = Integer.toString(n, 10) + "%";
    }

    public void setDisplaySize(int width, int height) {
        displayWidth = width;
        displayHeight = height;
    }

    public Color getProgressColor() {
        return progressColor;
    }

    public void setProgressColor(Color progressColor) {
        this.progressColor = progressColor;
    }
}

Here is a test program for the component:

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class T extends JFrame {
    public T() {
        super();
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLayout(null);
        this.setSize(350, 75);
        HumanProgressBar p = new HumanProgressBar();
        p.setValue(50);
        p.setBounds(15, 15, 300, 15);
        this.add(p);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new T();
            }
        });
    }
}