How can I create basic animation in Java?
Currently i am trying to implement a basic animation program using swing in Java.
But i am not getting whether my logic for program in correct or not.
My program implements Runnable, ActionListener interfaces and also extends JApplet.
I want to know that, is it necessary to differentiate start method of JApplet and Runnable?
And if yes then why..?
My program is basic balloon program, when I click on start button balloons start moving upward and comes to floor again. This will be continue till i press stop button.
Here is my code.
public class Balls extends JApplet implements Runnable{
private static final long serialVersionUID = 1L;
JPanel btnPanel=new JPanel();
static boolean flag1=true;
static boolean flag2=true;
static boolean flag3=false;
static int h;
static int temp=10;
Thread t=new Thread(this);
JButton start;
JButton stop;
public void init()
{
try
{
SwingUtilities.invokeAndWait(
new Runnable()
{
public void run()
{
makeGUI();
}
});
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null,"Can't create GUI because of exception");
System.exit(0);
}
}
private void makeGUI() {
start=new JButton("start");
stop=new JButton("stop");
btnPanel.add(start);
btnPanel.add(stop);
add(btnPanel,BorderLayout.NORTH);
}
public void run()
{
while(true)
{
if(flag1)
{
repaint();
flag1=false;
}
else
{
try
{
wait();
flag3=true;
}
catch(InterruptedException e)
{
JOptionPane.showMessageDialog(null,"Error ocuured !!\n Exiting..");
System.exit(0);
}
}
}
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
int h=Integer.parseInt(getParameter("height"));
if (flag1)
{
g.setColor(Color.RED);
g.fillOval(10,h,50,50);
g.setColor(Color.YELLOW);
g.fillOval(50,h,20,20);
g.setColor(Color.CYAN);
g.fillOval(70,h,80,30);
g.setColor(Color.BLUE);
g.fillOval(120,h,50,60);
g.setColor(Color.GRAY);
g.fillOval(160,h,70,50);
g.setColor(Color.GREEN);
g.fillOval(200,h,80,80);
g.setColor(Color.MAGENTA);
g.fillOval(260,h,80,30);
g.setColor(Color.DARK_GRAY);
g.fillOval(320,h,60,40);
g.setColor(Color.pink);
g.fillOval(370,h,65,45);
flag1=false;
}
else
{
g.setColor(Color.RED);
g.fillOval(10,h-temp,50,50);
g.setColor(Color.YELLOW);
g.fillOval(50,h-temp,20,20);
g.setColor(Color.CYAN);
g.fillOval(70,h-temp,80,30);
g.setColor(Color.BLUE);
g.fillOval(120,355,50,60);
g.setColor(Color.GRAY);
g.fillOval(160,h-temp,70,50);
g.setColor(Color.GREEN);
g.fillOval(200,h-temp,80,80);
g.setColor(Color.MAGENTA);
g.fillOval(260,h-temp,80,30);
g.setColor(Color.DARK_GRAY);
g.fillOval(320,h-temp,60,40);
g.setColor(Color.pink);
g.fillOval(370,h-temp,65,45);
if(flag2 && temp<=400)
{
temp+=10;
if(temp==400)
{
flag2=false;
}
}
else if(!flag2)
{
temp-=10;
if(temp==10)
{
flag2=true;
}
}
else
{
}
}
}
public void start()
{
start.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
t.start();
if(flag3)
{
notify();
}
}
});
stop.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
flag1=false;
try
{
Thread.sleep(5000);
}
catch(InterruptedException e)
{
repaint();
t=null;
}
}
});
}
}
1) Use SwingTimer as recommended instead of your Runnable implementation.
2) Read about custom painting , and here
3) draw at the JPanel instead of on JFrame
I have changed your code, examine it. I think, that it does what you want.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class Balls extends JApplet {
private static final long serialVersionUID = 1L;
JPanel btnPanel = new JPanel();
static boolean flag1 = true;
static boolean flag2 = true;
static boolean flag3 = false;
static int h;
static int temp = 10;
JButton start;
JButton stop;
private Timer timer;
public void init() {
SwingUtilities.invokeLater(
new Runnable() {
public void run() {
makeGUI();
}
});
}
private void makeGUI() {
timer = new Timer(10, new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
repaint();
}
});
start = new JButton("start");
stop = new JButton("stop");
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
timer.start();
}
});
stop.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
timer.stop();
}
});
btnPanel.add(start);
btnPanel.add(stop);
add(new MyPanel(), BorderLayout.CENTER);
add(btnPanel, BorderLayout.NORTH);
}
class MyPanel extends JPanel{
public void paintComponent(Graphics g) {
super.paintComponent(g);
int h = Integer.parseInt(getParameter("height"));
if (flag1) {
g.setColor(Color.RED);
g.fillOval(10, h, 50, 50);
g.setColor(Color.YELLOW);
g.fillOval(50, h, 20, 20);
g.setColor(Color.CYAN);
g.fillOval(70, h, 80, 30);
g.setColor(Color.BLUE);
g.fillOval(120, h, 50, 60);
g.setColor(Color.GRAY);
g.fillOval(160, h, 70, 50);
g.setColor(Color.GREEN);
g.fillOval(200, h, 80, 80);
g.setColor(Color.MAGENTA);
g.fillOval(260, h, 80, 30);
g.setColor(Color.DARK_GRAY);
g.fillOval(320, h, 60, 40);
g.setColor(Color.pink);
g.fillOval(370, h, 65, 45);
flag1 = false;
} else {
g.setColor(Color.RED);
g.fillOval(10, h - temp, 50, 50);
g.setColor(Color.YELLOW);
g.fillOval(50, h - temp, 20, 20);
g.setColor(Color.CYAN);
g.fillOval(70, h - temp, 80, 30);
g.setColor(Color.BLUE);
g.fillOval(120, 355, 50, 60);
g.setColor(Color.GRAY);
g.fillOval(160, h - temp, 70, 50);
g.setColor(Color.GREEN);
g.fillOval(200, h - temp, 80, 80);
g.setColor(Color.MAGENTA);
g.fillOval(260, h - temp, 80, 30);
g.setColor(Color.DARK_GRAY);
g.fillOval(320, h - temp, 60, 40);
g.setColor(Color.pink);
g.fillOval(370, h - temp, 65, 45);
if (flag2 && temp <= 400) {
temp += 10;
if (temp == 400) {
flag2 = false;
}
} else if (!flag2) {
temp -= 10;
if (temp == 10) {
flag2 = true;
}
} else {
}
}
}
}
}