问题
I am having trouble generating multiple oval shapes when clicking the panel of the frame. What I want is that it will generate many oval shapes and those shapes will move downward. One of the requirement is to use two multi threading. However in my case, the program I created is that, it will only generate one oval shape and the position is randomly changing. Can anyone please help me one this.
package ovalrandomcolors;
import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.List;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.Collections;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class OvalRandomColors extends JPanel{
private int ovalX = 50;
private int ovalY =50;
private int ovalPositionX = 250;
private int ovalPositionY = 250;
private Color color = Color.YELLOW;
public OvalRandomColors(){
setBackground(Color.DARK_GRAY);
}
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(color);
g.fillOval(ovalPositionX, ovalPositionY, ovalX, ovalY);
g.setColor(color);
g.fillOval(ovalPositionX, ovalPositionY, ovalX, ovalY);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
@Override
public void run() {
JFrame frame = new JFrame();
final OvalRandomColors oval = new OvalRandomColors();
oval.addMouseListener(new MouseAdapter(){
@Override
public void mouseClicked(MouseEvent e){
OvalWithThreading firstThread = new OvalWithThreading(oval);
OvalWithThreading secondThread = new OvalWithThreading(oval);
Thread first = new Thread(firstThread);
Thread second = new Thread(secondThread);
second.start();
first.start();
}
});
frame.add(oval);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,700);
frame.setVisible(true);
}
});
}
public void updateOval(){
int r = (int)(Math.random() * 255);
int g = (int) (Math.random() * 255);
int b = (int)(Math.random() * 255);
color = new Color(r,g,b);
ovalPositionX = (int)(Math.random() * 78);
ovalPositionY = (int) (Math.random() * 245);
animateOval();
repaint();
}
public void animateOval(){
// ovalPositionX += 30;
ovalPositionY += 30;
}
public static class OvalWithThreading implements Runnable{
private final OvalRandomColors ovalShape;
public OvalWithThreading(OvalRandomColors oS){
this.ovalShape = oS;
}
@Override
public void run() {
for(;;){
ovalShape.updateOval();
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
Logger.getLogger(OvalRandomColors.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
}
回答1:
Let's start with, Swing is not Thread safe, so having another Thread which update the state of objects which the UI depends to render requires some serious considerations. Normally, I'd recommend using a Swing Timer or SwingWorker to accomplish this, but those aren't the "requirements"
In order to render multiple objects, you need some way to store them, so you can update their states and renderer them. The simplest solution is a List, you can see Collections Trail for more details.
Now, if you also need to manage color, you can take a look at how I managed the deltas for each shape and should give you one idea for doing that
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.locks.ReentrantLock;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private ReentrantLock shapesLock = new ReentrantLock();
private List<Ellipse2D> shapes;
public TestPane() {
shapes = new ArrayList<>(25);
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
shapesLock.lock();
try {
shapes.add(new Ellipse2D.Double(e.getX() - 5, e.getY() - 5, 10, 10));
} finally {
shapesLock.unlock();
}
}
});
Thread t = new Thread(new Runnable() {
private Map<Shape, Double> deltas = new HashMap<>();
@Override
public void run() {
while (true) {
try {
shapesLock.lock();
try {
Rectangle containerBounds = getBounds();
containerBounds.setLocation(0, 0);
Iterator<Ellipse2D> it = shapes.iterator();
while (it.hasNext()) {
Ellipse2D shape = it.next();
Rectangle2D bounds = shape.getBounds2D();
double y = bounds.getY();
Double delta = deltas.get(shape);
if (delta == null) {
delta = 0d;
}
y += delta;
shape.setFrame(bounds.getX(), y, bounds.getWidth(), bounds.getHeight());
if (containerBounds.contains(shape.getBounds())) {
delta = Math.min(delta + 0.25, 6d);
deltas.put(shape, delta);
} else {
it.remove();
}
}
} finally {
shapesLock.unlock();
}
repaint();
Thread.sleep(40);
} catch (InterruptedException ex) {
}
}
}
});
t.setDaemon(false);
t.start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
shapesLock.lock();
try {
for (Ellipse2D shape : shapes) {
g2d.fill(shape);
}
} finally {
shapesLock.unlock();
}
g2d.dispose();
}
}
}
来源：https://stackoverflow.com/questions/35837747/how-to-generate-multiple-circle-shapes-and-animate-those-shapes-going-down-the-f