Dibujar y mover una figura o imagen con un ciclo o bucle en Java

[edme2000]

Buenos días estimados,

Quiero solicitar su valiosa ayuda,  necesito mover una figura con un ciclo for,   por ejemplo hacer que una pelota (circulo) se mueva horizontalmente de un lado hacia el otro.  Es importante mencionar que mi conocimiento de Java es mas de consola pero aún principiante.
He logrado mover la pelota con el mouse y presionando botones, utilizando paint y repaint, pero al aplicarlo al ciclo no logro que funcione.
 La aplicación que deseo hacer es aplicado a fisica. 

Les agradezco mucho la ayuda que puedan brindarme.

Saludos,

[Mastermind]

Hola, si eres principiante java este curso es el más recomendable: http://aprenderaprogramar.com/index.php?option=com_content&view=category&id=68&Itemid=188

El código siguiente es un código de ejemplo de un libro de aprendizaje Java con alguna modificación. Ejecuta el main de la clase test para ver el movimiento de un círculo:


CLASE TEST

Código: [Seleccionar]

public class test {
public static void main (String[] Args) {
    Picture p = new Picture();
    p.draw();
    p.hacerAtardecer();
}
}


CLASE CANVAS

Código: [Seleccionar]

import javax.swing.*;
import java.awt.*;
import java.util.List;
import java.util.*;

/**
 * Canvas is a class to allow for simple graphical drawing on a canvas.
 */
public class Canvas
{
    // Note: The implementation of this class (specifically the handling of
    // shape identity and colors) is slightly more complex than necessary. This
    // is done on purpose to keep the interface and instance fields of the
    // shape objects in this project clean and simple for educational purposes.

    private static Canvas canvasSingleton;

    /**
     * Factory method to get the canvas singleton object.
     */
    public static Canvas getCanvas()
    {
        if(canvasSingleton == null) {
            canvasSingleton = new Canvas("BlueJ Shapes Demo", 600, 600,
                                         Color.white);
        }
        canvasSingleton.setVisible(true);
        return canvasSingleton;
    }

    //  ----- instance part -----

    private JFrame frame;
    private CanvasPane canvas;
    private Graphics2D graphic;
    private Color backgroundColor;
    private Image canvasImage;
    private List<Object> objects;
    private HashMap<Object, ShapeDescription> shapes;
   
    /**
     * Create a Canvas.
     * @param title    title to appear in Canvas Frame
     * @param width    the desired width for the canvas
     * @param height   the desired height for the canvas
     * @param bgColor the desired background color of the canvas
     */
    private Canvas(String title, int width, int height, Color bgColor)
    {
        frame = new JFrame();
        canvas = new CanvasPane();
        frame.setContentPane(canvas);
        frame.setTitle(title);
        canvas.setPreferredSize(new Dimension(width, height));
        backgroundColor = bgColor;
        frame.pack();
        objects = new ArrayList<Object>();
        shapes = new HashMap<Object, ShapeDescription>();
    }

    /**
     * Set the canvas visibility and brings canvas to the front of screen
     * when made visible. This method can also be used to bring an already
     * visible canvas to the front of other windows.
     * @param visible  boolean value representing the desired visibility of
     * the canvas (true or false)
     */
    public void setVisible(boolean visible)
    {
        if(graphic == null) {
            // first time: instantiate the offscreen image and fill it with
            // the background color
            Dimension size = canvas.getSize();
            canvasImage = canvas.createImage(size.width, size.height);
            graphic = (Graphics2D)canvasImage.getGraphics();
            graphic.setColor(backgroundColor);
            graphic.fillRect(0, 0, size.width, size.height);
            graphic.setColor(Color.black);
        }
        frame.setVisible(visible);
    }

    /**
     * Draw a given shape onto the canvas.
     * @param  referenceObject  an object to define identity for this shape
     * @param  color            the color of the shape
     * @param  shape            the shape object to be drawn on the canvas
     */
     // Note: this is a slightly backwards way of maintaining the shape
     // objects. It is carefully designed to keep the visible shape interfaces
     // in this project clean and simple for educational purposes.
    public void draw(Object referenceObject, String color, Shape shape)
    {
        objects.remove(referenceObject);   // just in case it was already there
        objects.add(referenceObject);      // add at the end
        shapes.put(referenceObject, new ShapeDescription(shape, color));
        redraw();
    }
 
    /**
     * Erase a given shape's from the screen.
     * @param  referenceObject  the shape object to be erased
     */
    public void erase(Object referenceObject)
    {
        objects.remove(referenceObject);   // just in case it was already there
        shapes.remove(referenceObject);
        redraw();
    }

    /**
     * Set the foreground color of the Canvas.
     * @param  newColor   the new color for the foreground of the Canvas
     */
    public void setForegroundColor(String colorString)
    {
        if(colorString.equals("red")) {
            graphic.setColor(Color.red);
        }
        else if(colorString.equals("black")) {
            graphic.setColor(Color.black);
        }
        else if(colorString.equals("blue")) {
            graphic.setColor(Color.blue);
        }
        else if(colorString.equals("yellow")) {
            graphic.setColor(Color.yellow);
        }
        else if(colorString.equals("green")) {
            graphic.setColor(Color.green);
        }
        else if(colorString.equals("magenta")) {
            graphic.setColor(Color.magenta);
        }
        else if(colorString.equals("white")) {
            graphic.setColor(Color.white);
        }
        else {
            graphic.setColor(Color.black);
        }
    }

    /**
     * Wait for a specified number of milliseconds before finishing.
     * This provides an easy way to specify a small delay which can be
     * used when producing animations.
     * @param  milliseconds  the number
     */
    public void wait(int milliseconds)
    {
        try
        {
            Thread.sleep(milliseconds);
        }
        catch (Exception e)
        {
            // ignoring exception at the moment
        }
    }

    /**
     * Redraw ell shapes currently on the Canvas.
     */
    private void redraw()
    {
        erase();
        for(Object shape : objects) {
            shapes.get(shape).draw(graphic);
        }
        canvas.repaint();
    }
       
    /**
     * Erase the whole canvas. (Does not repaint.)
     */
    private void erase()
    {
        Color original = graphic.getColor();
        graphic.setColor(backgroundColor);
        Dimension size = canvas.getSize();
        graphic.fill(new Rectangle(0, 0, size.width, size.height));
        graphic.setColor(original);
    }


    /************************************************************************
     * Inner class CanvasPane - the actual canvas component contained in the
     * Canvas frame. This is essentially a JPanel with added capability to
     * refresh the image drawn on it.
     */
    private class CanvasPane extends JPanel
    {
        public void paint(Graphics g)
        {
            g.drawImage(canvasImage, 0, 0, null);
        }
    }
   
    /************************************************************************
     * Inner class CanvasPane - the actual canvas component contained in the
     * Canvas frame. This is essentially a JPanel with added capability to
     * refresh the image drawn on it.
     */
    private class ShapeDescription
    {
        private Shape shape;
        private String colorString;

        public ShapeDescription(Shape shape, String color)
        {
            this.shape = shape;
            colorString = color;
        }

        public void draw(Graphics2D graphic)
        {
            setForegroundColor(colorString);
            graphic.fill(shape);
        }
    }

}




CLASE DIBUJO

Código: [Seleccionar]

public class Picture
{
    private Square wall;
    private Square window;
    private Triangle roof;
    private Circle sun;

    /**
     * Constructor for objects of class Picture
     */
    public Picture()
    {
        // nothing to do... instance variables are automatically set to null
    }

    /**
     * Draw this picture.
     */
    public void draw()
    {
        wall = new Square();
        wall.moveVertical(80);
        wall.changeSize(100);
        wall.makeVisible();

        window = new Square();
        window.changeColor("black");
        window.moveHorizontal(20);
        window.moveVertical(100);
        window.makeVisible();

        roof = new Triangle(); 
        roof.changeSize(50, 140);
        roof.moveHorizontal(60);
        roof.moveVertical(70);
        roof.makeVisible();

        sun = new Circle();
        sun.changeColor("yellow");
        sun.moveHorizontal(180);
        sun.moveVertical(-10);
        sun.changeSize(60);
        sun.makeVisible();

    }
    /**
     * Change this picture to black/white display
     */
    public void setBlackAndWhite()
    {
        if(wall != null)   // only if it's painted already...
        {
            wall.changeColor("black");
            window.changeColor("white");
            roof.changeColor("black");
            sun.changeColor("black");
        }
    }

    /**
     * Change this picture to use color display
     */
    public void setColor()
    {
        if(wall != null)   // only if it's painted already...
        {
            wall.changeColor("red");
            window.changeColor("black");
            roof.changeColor("green");
            sun.changeColor("yellow");
        }
    }

    /**
     * Genera un efecto atardecer haciendo bajar el sol
     */
    public void hacerAtardecer()
    {
        if(wall != null)   // only if it's painted already...
        {
            sun.slowMoveVertical(150);
        }
    }
}

Continúa en el siguiente post -- >

[Mastermind]

Continuación del código del ejemplo:

CLASE CIRCULO

Código: [Seleccionar]

import java.awt.*;
import java.awt.geom.*;

/**
 * A circle that can be manipulated and that draws itself on a canvas.
 */

public class Circle
{
    private int diameter;
    private int xPosition;
    private int yPosition;
    private String color;
    private boolean isVisible;

    /**
     * Create a new circle at default position with default color.
     */
    public Circle()
    {
        diameter = 40;
        xPosition = 20;
        yPosition = 60;
        color = "blue";
        isVisible = false;
    }

    /**
     * Make this circle visible. If it was already visible, do nothing.
     */
    public void makeVisible()
    {
        isVisible = true;
        draw();
    }

    /**
     * Make this circle invisible. If it was already invisible, do nothing.
     */
    public void makeInvisible()
    {
        erase();
        isVisible = false;
    }

    /**
     * Move the circle a few pixels to the right.
     */
    public void moveRight()
    {
        moveHorizontal(20);
    }

    /**
     * Move the circle a few pixels to the left.
     */
    public void moveLeft()
    {
        moveHorizontal(-20);
    }

    /**
     * Move the circle a few pixels up.
     */
    public void moveUp()
    {
        moveVertical(-20);
    }

    /**
     * Move the circle a few pixels down.
     */
    public void moveDown()
    {
        moveVertical(20);
    }

    /**
     * Move the circle horizontally by 'distance' pixels.
     */
    public void moveHorizontal(int distance)
    {
        erase();
        xPosition += distance;
        draw();
    }

    /**
     * Move the circle vertically by 'distance' pixels.
     */
    public void moveVertical(int distance)
    {
        erase();
        yPosition += distance;
        draw();
    }

    /**
     * Slowly move the circle horizontally by 'distance' pixels.
     */
    public void slowMoveHorizontal(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            xPosition += delta;
            draw();
        }
    }

    /**
     * Slowly move the circle vertically by 'distance' pixels.
     */
    public void slowMoveVertical(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            yPosition += delta;
            draw();
        }
    }

    /**
     * Change the size to the new size (in pixels). Size must be >= 0.
     */
    public void changeSize(int newDiameter)
    {
        erase();
        diameter = newDiameter;
        draw();
    }

    /**
     * Change the color. Valid colors are "red", "yellow", "blue", "green",
     * "magenta" and "black".
     */
    public void changeColor(String newColor)
    {
        color = newColor;
        draw();
    }

    /**
     * Draw the circle with current specifications on screen.
     */
    private void draw()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            canvas.draw(this, color, new Ellipse2D.Double(xPosition, yPosition,
                    diameter, diameter));
            canvas.wait(10);
        }
    }

    /**
     * Erase the circle on screen.
     */
    private void erase()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            canvas.erase(this);
        }
    }
}




CLASE CUADRADO

Código: [Seleccionar]

import java.awt.*;

/**
 * A square that can be manipulated and that draws itself on a canvas.
 */

public class Square
{
    private int size;
    private int xPosition;
    private int yPosition;
    private String color;
    private boolean isVisible;

    /**
     * Create a new square at default position with default color.
     */
    public Square()
    {
        size = 30;
        xPosition = 60;
        yPosition = 50;
        color = "red";
        isVisible = false;
    }

    /**
     * Make this square visible. If it was already visible, do nothing.
     */
    public void makeVisible()
    {
        isVisible = true;
        draw();
    }
   
    /**
     * Make this square invisible. If it was already invisible, do nothing.
     */
    public void makeInvisible()
    {
        erase();
        isVisible = false;
    }
   
    /**
     * Move the square a few pixels to the right.
     */
    public void moveRight()
    {
        moveHorizontal(20);
    }

    /**
     * Move the square a few pixels to the left.
     */
    public void moveLeft()
    {
        moveHorizontal(-20);
    }

    /**
     * Move the square a few pixels up.
     */
    public void moveUp()
    {
        moveVertical(-20);
    }

    /**
     * Move the square a few pixels down.
     */
    public void moveDown()
    {
        moveVertical(20);
    }

    /**
     * Move the square horizontally by 'distance' pixels.
     */
    public void moveHorizontal(int distance)
    {
        erase();
        xPosition += distance;
        draw();
    }

    /**
     * Move the square vertically by 'distance' pixels.
     */
    public void moveVertical(int distance)
    {
        erase();
        yPosition += distance;
        draw();
    }

    /**
     * Slowly move the square horizontally by 'distance' pixels.
     */
    public void slowMoveHorizontal(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            xPosition += delta;
            draw();
        }
    }

    /**
     * Slowly move the square vertically by 'distance' pixels.
     */
    public void slowMoveVertical(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            yPosition += delta;
            draw();
        }
    }

    /**
     * Change the size to the new size (in pixels). Size must be >= 0.
     */
    public void changeSize(int newSize)
    {
        erase();
        size = newSize;
        draw();
    }

    /**
     * Change the color. Valid colors are "red", "yellow", "blue", "green",
     * "magenta" and "black".
     */
    public void changeColor(String newColor)
    {
        color = newColor;
        draw();
    }

    /**
     * Draw the square with current specifications on screen.
     */
    private void draw()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            canvas.draw(this, color,
                        new Rectangle(xPosition, yPosition, size, size));
            canvas.wait(10);
        }
    }

    /**
     * Erase the square on screen.
     */
    private void erase()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            canvas.erase(this);
        }
    }
}





CLASE TRIANGULO

Código: [Seleccionar]

import java.awt.*;

/**
 * A triangle that can be manipulated and that draws itself on a canvas.
 */

public class Triangle
{
    private int height;
    private int width;
    private int xPosition;
    private int yPosition;
    private String color;
    private boolean isVisible;

    /**
     * Create a new triangle at default position with default color.
     */
    public Triangle()
    {
        height = 30;
        width = 40;
        xPosition = 50;
        yPosition = 15;
        color = "green";
        isVisible = false;
    }

    /**
     * Make this triangle visible. If it was already visible, do nothing.
     */
    public void makeVisible()
    {
        isVisible = true;
        draw();
    }
   
    /**
     * Make this triangle invisible. If it was already invisible, do nothing.
     */
    public void makeInvisible()
    {
        erase();
        isVisible = false;
    }
   
    /**
     * Move the triangle a few pixels to the right.
     */
    public void moveRight()
    {
        moveHorizontal(20);
    }

    /**
     * Move the triangle a few pixels to the left.
     */
    public void moveLeft()
    {
        moveHorizontal(-20);
    }

    /**
     * Move the triangle a few pixels up.
     */
    public void moveUp()
    {
        moveVertical(-20);
    }

    /**
     * Move the triangle a few pixels down.
     */
    public void moveDown()
    {
        moveVertical(20);
    }

    /**
     * Move the triangle horizontally by 'distance' pixels.
     */
    public void moveHorizontal(int distance)
    {
        erase();
        xPosition += distance;
        draw();
    }

    /**
     * Move the triangle vertically by 'distance' pixels.
     */
    public void moveVertical(int distance)
    {
        erase();
        yPosition += distance;
        draw();
    }

    /**
     * Slowly move the triangle horizontally by 'distance' pixels.
     */
    public void slowMoveHorizontal(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            xPosition += delta;
            draw();
        }
    }

    /**
     * Slowly move the triangle vertically by 'distance' pixels.
     */
    public void slowMoveVertical(int distance)
    {
        int delta;

        if(distance < 0)
        {
            delta = -1;
            distance = -distance;
        }
        else
        {
            delta = 1;
        }

        for(int i = 0; i < distance; i++)
        {
            yPosition += delta;
            draw();
        }
    }

    /**
     * Change the size to the new size (in pixels). Size must be >= 0.
     */
    public void changeSize(int newHeight, int newWidth)
    {
        erase();
        height = newHeight;
        width = newWidth;
        draw();
    }

    /**
     * Change the color. Valid colors are "red", "yellow", "blue", "green",
     * "magenta" and "black".
     */
    public void changeColor(String newColor)
    {
        color = newColor;
        draw();
    }

    /**
     * Draw the triangle with current specifications on screen.
     */
    private void draw()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            int[] xpoints = { xPosition, xPosition + (width/2), xPosition - (width/2) };
            int[] ypoints = { yPosition, yPosition + height, yPosition + height };
            canvas.draw(this, color, new Polygon(xpoints, ypoints, 3));
            canvas.wait(10);
        }
    }

    /**
     * Erase the triangle on screen.
     */
    private void erase()
    {
        if(isVisible) {
            Canvas canvas = Canvas.getCanvas();
            canvas.erase(this);
        }
    }
}