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How to refresh/reload an image in Swing GUI as the real image file changes?

I am trying to implement Remote FrameBuffer Protocol using Java socket programming.
I have a server side program that takes screenshot of the entire screen using robot and store it in BufferedImage .Then I converted it into a byte array and sending it to the client .
Objective :
To display the entire screen of the server side machine in a Swing GUI of the client side.
Problem i am facing :
i am able to send the image in bytes from server and receive it from the server by the client (client.java) and convert it into a jpg image (output.jpg) using ImageIO and put that image in a Swing frame.
But i am able to see the first image in the Swing and whenever the image gets updated ,the image in the Swing is not updating or refreshing .
What I want :
I want the image to refresh and show updated image every time the server sends the image data .
client.java
package remoteclient;
import java.lang.*;
import javax.imageio.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import java.net.*;
import java.io.*;
public class client {
public static void main(String args[])throws Exception{
Socket s=new Socket("localhost",5900);
DataInputStream din=new DataInputStream(s.getInputStream());
DataOutputStream dout=new DataOutputStream(s.getOutputStream());
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int width=0,height=0;
try {
width = din.readInt(); //getting width and height from server thru socket.
height = din.readInt();
} catch (Exception e) {
e.printStackTrace();
}
JFrame f = new JFrame("Client");
JLabel label = new JLabel();
f.setSize(width, height);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
boolean continueLoop = true;
while(continueLoop)
{
try {
int len = din.readInt();
byte[] imageInByte = new byte[len];
System.out.println(len);
din.readFully(imageInByte);
System.out.println(imageInByte);
ByteArrayInputStream bis = new ByteArrayInputStream(imageInByte);
BufferedImage bImage2 = ImageIO.read(bis);
// Image im1 = bImage2.getScaledInstance(width,height, Image.SCALE_SMOOTH);
ImageIO.write(bImage2, "jpg", new File("output.jpg") );
bImage2 = ImageIO.read(new File("output.jpg"));
label.setIcon(new ImageIcon(im1));
ImageIcon icon = new ImageIcon(bImage2);
icon.getImage().flush();
label.setIcon( icon );
f.getContentPane().add(label, BorderLayout.CENTER);
f.pack();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
What I want :
I want the image to refresh and show updated image every time the server sends the image data .

Updated code with comments about demo code that should be removed from your working code:
Here's an example, using default UIManager icons, and SwingWorker, as noted in the comments to the original posting. You would instead use images from your server connection.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
public class SwingLabelWithUpdatedImage {
public static void main(String args[]) throws Exception {
final JLabel label = new JLabel("", SwingConstants.CENTER);
final JFrame frame = new JFrame("Client");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(label, BorderLayout.CENTER);
final Dimension preferredSize = new Dimension(200, 100);
frame.setPreferredSize(preferredSize);
frame.setVisible(true);
frame.pack();
final ImageUpdateWorker task = new ImageUpdateWorker(label);
task.execute();
}
public static class ImageUpdateWorker extends SwingWorker<Void, IconInfo> {
// iconInfoList is not need in your code. It's here so I can
// supply a dummy set of icons to demonstrate UI updates.
final List<IconInfo> iconInfoList;
private JLabel label;
ImageUpdateWorker(JLabel label) {
this.label = label;
// Delete this in your code
this.iconInfoList = initIconInfoList();
}
#Override
public Void doInBackground() {
boolean isTrue = true;
while (isTrue) {
// Put your socket code to read the next icon from a server.
// You don't need to do the ImageIO.write(), ImageIO.read() dance,
// unless you must save the icon to disk. In that case, you don't need
// to read it back in.
// Here, I just rotate the iconInfoList to make it
// appear as though a new icon was received.
// Your code will not have any need to do this.
Collections.rotate(iconInfoList, -1);
// Just publish the icon you create from the image
// you receive from your remote server.
publish(iconInfoList.get(0));
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void process(List<IconInfo> icons) {
// You might check for an empty list.
// #kleopatra's suggestion to get the last icon is correct.
// See https://docs.oracle.com/javase/tutorial/uiswing/concurrency/interim.html
IconInfo iconInfo = icons.get(icons.size() - 1);
label.setIcon(iconInfo.icon);
// Your code will not do this
label.setText(iconInfo.name);
// You can get the icon dimensions just from the icon,
// so you don't really need the IconInfo class.
label.setSize(iconInfo.dimension);
}
/** Demo code only. It doesn't belong in your working code.
*/
protected List<IconInfo> initIconInfoList() {
// Just a quick way to get some icons; don't need to
// fetch from a server just to demonstrate how to
// refresh the UI.
List<IconInfo> iconInfoList = UIManager.getDefaults().keySet().stream()
.filter(this::isIconKey)
.map(IconInfo::new)
.filter(iconInfo -> iconInfo.icon != null)
.collect(Collectors.toList());
return iconInfoList;
}
/** Demo code only. It doesn't belong in your working code.
*/
protected boolean isIconKey(Object key) {
return String.class.isAssignableFrom(key.getClass())
&& ((String) key).toLowerCase().contains("icon");
}
}
/** This is just a convenience to convey
* the icon and its UIManager key (i.e., name).
* Your remote server doesn't supply a name,
* so you don't really need this class.
* It's just to make the demo more expressive.
*/
public static class IconInfo {
final private String name;
final private Icon icon;
final private Dimension dimension;
IconInfo(Object name) {
this.name = name.toString();
icon = UIManager.getIcon(name);
dimension = icon == null
? new Dimension(32, 32)
: new Dimension(icon.getIconWidth(), icon.getIconHeight());
}
}
}

Can someone tell me where is it picking images from?

package demo;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/*`enter code here`
* ComboBoxDemo.java uses these additional files:`enter code here`
* images/Bird.gif
* images/Cat.gif
* images/Dog.gif
* images/Rabbit.gif
* images/Pig.gif
*/
public class Demo extends JPanel
implements ActionListener {
JLabel picture;
#SuppressWarnings({ "rawtypes", "unchecked" })
public Demo() {
super(new BorderLayout());
String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };
//Create the combo box, select the item at index 4.
//Indices start at 0, so 4 specifies the pig.
JComboBox petList = new JComboBox(petStrings);
petList.setSelectedIndex(4);
petList.addActionListener(this);
//Set up the picture.
picture = new JLabel();
picture.setFont(picture.getFont().deriveFont(Font.ITALIC));
picture.setHorizontalAlignment(JLabel.CENTER);
updateLabel(petStrings[petList.getSelectedIndex()]);
picture.setBorder(BorderFactory.createEmptyBorder(10,0,0,0));
//The preferred size is hard-coded to be the width of the
//widest image and the height of the tallest image + the border.
//A real program would compute this.
picture.setPreferredSize(new Dimension(177, 122+10));
//Lay out the demo.
add(petList, BorderLayout.PAGE_START);
add(picture, BorderLayout.PAGE_END);
setBorder(BorderFactory.createEmptyBorder(20,20,20,20));
}
/** Listens to the combo box. */
public void actionPerformed(ActionEvent e) {
JComboBox cb = (JComboBox)e.getSource();
String petName = (String)cb.getSelectedItem();
updateLabel(petName);
}
protected void updateLabel(String name) {
ImageIcon icon = createImageIcon("images/" + name + ".png");
picture.setIcon(icon);
picture.setToolTipText("A drawing of a " + name.toLowerCase());
if (icon != null) {
picture.setText(null);
} else {
picture.setText("Image not found");
}
}
/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String path) {
java.net.URL imgURL = Demo.class.getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("ComboBoxDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new Demo();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
This is the code i have got from oracle but i don't know where it would need to pick images from because every time i create a source folder with images, it still wouldn't pick it up. Or if you could tell me which part of the code is picking the image up? I need to use same kinda code for my work.

ImageIcon icon = createImageIcon("images/" + name + ".png");
This line is providing image path which is images/name.png and value of name could be among these {"Bird", "Cat", "Dog", "Rabbit", "Pig"}
picture.setIcon(icon);
The above line is setting the icon to JLabel picture.
Create a folder named images in root directory of the project and put all .png images in images folder.

If you want to debug where the program fetches the files, you could use the following creating a File object and requesting it's absolute path.
Ideone
System.out.println(new File("images/Bird.png").getAbsolutePath()); // C:\... or /...

See: http://www.thinkplexx.com/learn/howto/java/system/java-resource-loading-explained-absolute-and-relative-names-difference-between-classloader-and-class-resource-loading
I finally found out where the problem lies, but I cannot understand why they way Oracle made the code doesn't work.
Go back to the original code published at
https://www.codetantra.com/java/jdk6.0/tutorial/uiswing/examples/components/ComboBoxDemoProject/src/components/ComboBoxDemo.java
You need to go to the folder where your project is. You will see:
bin
images
src
The images folder may have all the expected image files in it, but the program does not get to them somehow. Copy the gif files into the folder that holds bin, images, and src.
You will now see:
bin
images
src
Bird.gif
Cat.gif
and so forth.
Now go back and change Oracle's code:
// ImageIcon icon = createImageIcon("images/" + name + ".gif"); //This way does not work.
to
ImageIcon icon = createImageIcon(name + ".gif");

Create a folder named images in the same folder where your Demo.java is. And place your images there. The image names, according to your code, are "Bird.png", "Cat.png", "Dog.png", "Rabbit.png", "Pig.png".
So your project structure is something like this:
demo
src
└───demo
│ Demo.java
└───images
Bird.png
Cat.png
Dog.png
Rabbit.png
Pig.png

Adding links to options in a Input Dialog

I'm trying to add links into a project that i'm making in eclipse. I have researched on how to do it, but i can't find much on it that pertains to eclipse.
This is the code that im trying to add links too:
Object[] possibilities = {"" +
"AWS Welder Certification Testing",
"Computer science",
"Aviation", "Construction",
"Health science",
"Programming",
"3D design",
"Cyber security",
"Advanced Safety Certification",
"Healthcare Provider CPR",
"Dietary Manager",
"Insurance",
"Emergency 911 Operator",
"Job Safety Analysis",
"Real Estate",
"Pharmacy Technician",
"Special Needs Education",
"School Bus Driver Training",
"Phlebotomy Technician",
"Security Guard",
"Home Inspection",
"Court Reporter",
"Long Term Care/Nurse Aide (CNA)",
"EPA Lead Safe Renovator Certification",};
Component frame = null;
Icon icon = null;
String s = (String)JOptionPane.showInputDialog(
frame,
"What class might you want to attend?\n"
+ "\"The options are endless!\"",
"Class Options",
JOptionPane.PLAIN_MESSAGE,
icon,
possibilities,
"all");
When I run the program, a dialog box appears, and it gives all the options of classes above. How would I make it to where when the user clicks on a class it will link them to the website for that class?

I recommend using a JTextField rather than a JButton for this use.
E.G.
That is how it appears when the mouse is hovering over the first link.
LinkLabel.java
/* License - LGPL
LinkLabel Using the Desktop Class
There are a lot of link labels. This one uses the Java 1.6+
Desktop class for its functionality, and is thereby suitable
for applets, applications launched using JWS, and 'standard'
(non-JWS) desktop applications.
*/
import java.awt.Desktop;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.JTextField;
import javax.swing.JPanel;
import javax.swing.JOptionPane;
import javax.swing.border.MatteBorder;
import javax.swing.border.Border;
import java.net.URI;
import java.io.File;
/**
A Java 1.6+ LinkLabel that uses the Desktop class for opening
the document of interest.
The Desktop.browse(URI) method can be invoked from applications,
applets and apps. launched using Java Webstart. In the latter
two cases, the usual fall-back methods are used for sandboxed apps
(see the JavaDocs for further details).
While called a 'label', this class actually extends JTextField,
to easily allow the component to become focusable using keyboard
navigation.
To successfully browse to a URI for a local File, the file name
must be constructed using a canonical path.
#author Andrew Thompson
#version 2008/08/23
*/
public class LinkLabel
// we extend a JTextField, to get a focusable component
extends JTextField
implements MouseListener, FocusListener, ActionListener {
/** The target or href of this link. */
private URI target;
public Color standardColor = new Color(0,0,255);
public Color hoverColor = new Color(255,0,0);
public Color activeColor = new Color(128,0,128);
public Color transparent = new Color(0,0,0,0);
public boolean underlineVisible = true;
private Border activeBorder;
private Border hoverBorder;
private Border standardBorder;
/** Construct a LinkLabel that points to the given target.
The URI will be used as the link text.*/
public LinkLabel(URI target) {
this( target, target.toString() );
}
/** Construct a LinkLabel that points to the given target,
and displays the text to the user. */
public LinkLabel(URI target, String text) {
super(text);
this.target = target;
}
/* Set the active color for this link (default is purple). */
public void setActiveColor(Color active) {
activeColor = active;
}
/* Set the hover/focused color for this link (default is red). */
public void setHoverColor(Color hover) {
hoverColor = hover;
}
/* Set the standard (non-focused, non-active) color for this
link (default is blue). */
public void setStandardColor(Color standard) {
standardColor = standard;
}
/** Determines whether the */
public void setUnderlineVisible(boolean underlineVisible) {
this.underlineVisible = underlineVisible;
}
/* Add the listeners, configure the field to look and act
like a link. */
public void init() {
this.addMouseListener(this);
this.addFocusListener(this);
this.addActionListener(this);
setToolTipText(target.toString());
if (underlineVisible) {
activeBorder = new MatteBorder(0,0,1,0,activeColor);
hoverBorder = new MatteBorder(0,0,1,0,hoverColor);
standardBorder = new MatteBorder(0,0,1,0,transparent);
} else {
activeBorder = new MatteBorder(0,0,0,0,activeColor);
hoverBorder = new MatteBorder(0,0,0,0,hoverColor);
standardBorder = new MatteBorder(0,0,0,0,transparent);
}
// make it appear like a label/link
setEditable(false);
setForeground(standardColor);
setBorder(standardBorder);
setCursor( new Cursor(Cursor.HAND_CURSOR) );
}
/** Browse to the target URI using the Desktop.browse(URI)
method. For visual indication, change to the active color
at method start, and return to the standard color once complete.
This is usually so fast that the active color does not appear,
but it will take longer if there is a problem finding/loading
the browser or URI (e.g. for a File). */
public void browse() {
setForeground(activeColor);
setBorder(activeBorder);
try {
Desktop.getDesktop().browse(target);
} catch(Exception e) {
e.printStackTrace();
}
setForeground(standardColor);
setBorder(standardBorder);
}
/** Browse to the target. */
public void actionPerformed(ActionEvent ae) {
browse();
}
/** Browse to the target. */
public void mouseClicked(MouseEvent me) {
browse();
}
/** Set the color to the hover color. */
public void mouseEntered(MouseEvent me) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
/** Set the color to the standard color. */
public void mouseExited(MouseEvent me) {
setForeground(standardColor);
setBorder(standardBorder);
}
public void mouseReleased(MouseEvent me) {}
public void mousePressed(MouseEvent me) {}
/** Set the color to the standard color. */
public void focusLost(FocusEvent fe) {
setForeground(standardColor);
setBorder(standardBorder);
}
/** Set the color to the hover color. */
public void focusGained(FocusEvent fe) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
public static void main(String[] args) throws Exception {
JPanel p = new JPanel(new GridLayout(0,1));
File f = new File(".","LinkLabel.java");
/* Filename must be constructed with a canonical path in
order to successfully use Desktop.browse(URI)! */
f = new File(f.getCanonicalPath());
URI uriFile = f.toURI();
LinkLabel linkLabelFile = new LinkLabel(uriFile);
linkLabelFile.init();
p.add(linkLabelFile);
LinkLabel linkLabelWeb = new LinkLabel(
new URI("http://pscode.org/sscce.html"),
"SSCCE");
linkLabelWeb.setStandardColor(new Color(0,128,0));
linkLabelWeb.setHoverColor(new Color(222,128,0));
linkLabelWeb.init();
/* This shows a quirk of the LinkLabel class, the
size of the text field needs to be constrained to
get the underline to appear properly. */
p.add(linkLabelWeb);
LinkLabel linkLabelConstrain = new LinkLabel(
new URI("http://sdnshare.sun.com/"),
"SDN Share");
linkLabelConstrain.init();
/* ..and this shows one way to constrain the size
(appropriate for this layout).
Similar tricks can be used to ensure the underline does
not drop too far *below* the link (think BorderLayout
NORTH/SOUTH).
The same technique can also be nested further to produce
a NORTH+EAST packing (for example). */
JPanel labelConstrain = new JPanel(new BorderLayout());
labelConstrain.add( linkLabelConstrain, BorderLayout.EAST );
p.add(labelConstrain);
LinkLabel linkLabelNoUnderline = new LinkLabel(
new URI("http://java.net/"),
"java.net");
// another way to deal with the underline is to remove it
linkLabelNoUnderline.setUnderlineVisible(false);
// we can use the methods inherited from JTextField
linkLabelNoUnderline.
setHorizontalAlignment(JTextField.CENTER);
linkLabelNoUnderline.init();
p.add(linkLabelNoUnderline);
JOptionPane.showMessageDialog( null, p );
}
}

Best practice for setting JFrame locations

I have a (somewhat philosophical) question relatively to Swing, or to GUI programming in general. Are there recognized best practices on where to locate the JFrame instances used in the application?
Where should the first and main frame be located? Always at the center (setLocationRelativeTo(null))?
Where should a child JFrame be located? Relatively to its parent JFrame, at the center of the screen, wherever we want?
I have always assumed there were some best practices, kind of a "GUI bible" about this, am I wrong and should I (gasp) arbitrarily decide what to do?

Here is an example that incorporates the advice of:
Hovercraft Full Of Eels - set location by platform.
Aardvocate Akintayo Olu - serialize the location.
But goes on to add 2 tweaks:
Serialize the width/height as well.
If the frame is maximized at time of close, it is restored before getting the bounds. (I detest apps. that serialize options but do not take that into account. The user is sitting there clicking the 'Maximize / Restore' button & wondering why nothing is happening!)
The 4 points combined offer the best user experience!
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Properties;
import java.io.*;
class RestoreMe {
/** This will end up in the current directory
A more sensible location is a sub-directory of user.home.
(left as an exercise for the reader) */
public static final String fileName = "options.prop";
/** Store location & size of UI */
public static void storeOptions(Frame f) throws Exception {
File file = new File(fileName);
Properties p = new Properties();
// restore the frame from 'full screen' first!
f.setExtendedState(Frame.NORMAL);
Rectangle r = f.getBounds();
int x = (int)r.getX();
int y = (int)r.getY();
int w = (int)r.getWidth();
int h = (int)r.getHeight();
p.setProperty("x", "" + x);
p.setProperty("y", "" + y);
p.setProperty("w", "" + w);
p.setProperty("h", "" + h);
BufferedWriter br = new BufferedWriter(new FileWriter(file));
p.store(br, "Properties of the user frame");
}
/** Restore location & size of UI */
public static void restoreOptions(Frame f) throws IOException {
File file = new File(fileName);
Properties p = new Properties();
BufferedReader br = new BufferedReader(new FileReader(file));
p.load(br);
int x = Integer.parseInt(p.getProperty("x"));
int y = Integer.parseInt(p.getProperty("y"));
int w = Integer.parseInt(p.getProperty("w"));
int h = Integer.parseInt(p.getProperty("h"));
Rectangle r = new Rectangle(x,y,w,h);
f.setBounds(r);
}
public static void main(String[] args) {
final JFrame f = new JFrame("Good Location & Size");
f.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
f.addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent we) {
try {
storeOptions(f);
} catch(Exception e) {
e.printStackTrace();
}
System.exit(0);
}
});
JTextArea ta = new JTextArea(20,50);
f.add(ta);
f.pack();
File optionsFile = new File(fileName);
if (optionsFile.exists()) {
try {
restoreOptions(f);
} catch(IOException ioe) {
ioe.printStackTrace();
}
} else {
f.setLocationByPlatform(true);
}
f.setVisible(true);
}
}

I've usually let the platform decide by calling:
myJFrame.setLocationByPlatform(true);
This lets the window "appear at the default location for the native windowing system". For more on this: Window API

What I always do is start at the center of the screen for main frame, or at the center of a parent for child frames, I record this location. Then as users move the frames to wherever they want I record the new location and when next the app is started, I use the last location to place the frame.

Not sure if there's a best practice as it is very subjective.
Setting it at the center and allowing users to change it to the location they like seems to be the ideal one.
As regards to the child frame, depending on its size, in the center of the parent frame, or just something easy to use.

Capturing image from webcam in java?

How can I continuously capture images from a webcam?
I want to experiment with object recognition (by maybe using java media framework).
I was thinking of creating two threads
one thread:
Node 1: capture live image
Node 2: save image as "1.jpg"
Node 3: wait 5 seconds
Node 4: repeat...
other thread:
Node 1: wait until image is captured
Node 2: using the "1.jpg" get colors
from every pixle
Node 3: save data in arrays
Node 4: repeat...

This JavaCV implementation works fine.
Code:
import org.bytedeco.javacv.*;
import org.bytedeco.opencv.opencv_core.IplImage;
import java.io.File;
import static org.bytedeco.opencv.global.opencv_core.cvFlip;
import static org.bytedeco.opencv.helper.opencv_imgcodecs.cvSaveImage;
public class Test implements Runnable {
final int INTERVAL = 100;///you may use interval
CanvasFrame canvas = new CanvasFrame("Web Cam");
public Test() {
canvas.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
}
public void run() {
new File("images").mkdir();
FrameGrabber grabber = new OpenCVFrameGrabber(0); // 1 for next camera
OpenCVFrameConverter.ToIplImage converter = new OpenCVFrameConverter.ToIplImage();
IplImage img;
int i = 0;
try {
grabber.start();
while (true) {
Frame frame = grabber.grab();
img = converter.convert(frame);
//the grabbed frame will be flipped, re-flip to make it right
cvFlip(img, img, 1);// l-r = 90_degrees_steps_anti_clockwise
//save
cvSaveImage("images" + File.separator + (i++) + "-aa.jpg", img);
canvas.showImage(converter.convert(img));
Thread.sleep(INTERVAL);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Test gs = new Test();
Thread th = new Thread(gs);
th.start();
}
}
There is also post on configuration for JavaCV
You can modify the code and be able to save the images in regular interval and do rest of the processing you want.

Some time ago I've created generic Java library which can be used to take pictures with a PC webcam. The API is very simple, not overfeatured, can work standalone, but also supports additional webcam drivers like OpenIMAJ, JMF, FMJ, LTI-CIVIL, etc, and some IP cameras.
Link to the project is https://github.com/sarxos/webcam-capture
Example code (take picture and save in test.jpg):
Webcam webcam = Webcam.getDefault();
webcam.open();
BufferedImage image = webcam.getImage();
ImageIO.write(image, "JPG", new File("test.jpg"));
It is also available in Maven Central Repository or as a separate ZIP which includes all required dependencies and 3rd party JARs.

JMyron is very simple for use.
http://webcamxtra.sourceforge.net/
myron = new JMyron();
myron.start(imgw, imgh);
myron.update();
int[] img = myron.image();

Here is a similar question with some - yet unaccepted - answers. One of them mentions FMJ as a java alternative to JMF.

This kind of goes off of gt_ebuddy's answer using JavaCV, but my video output is at a much higher quality then his answer. I've also added some other random improvements (such as closing down the program when ESC and CTRL+C are pressed, and making sure to close down the resources the program uses properly).
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.KeyStroke;
import com.googlecode.javacv.CanvasFrame;
import com.googlecode.javacv.OpenCVFrameGrabber;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
public class HighRes extends JComponent implements Runnable {
private static final long serialVersionUID = 1L;
private static CanvasFrame frame = new CanvasFrame("Web Cam");
private static boolean running = false;
private static int frameWidth = 800;
private static int frameHeight = 600;
private static OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0);
private static BufferedImage bufImg;
public HighRes()
{
// setup key bindings
ActionMap actionMap = frame.getRootPane().getActionMap();
InputMap inputMap = frame.getRootPane().getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
for (Keys direction : Keys.values())
{
actionMap.put(direction.getText(), new KeyBinding(direction.getText()));
inputMap.put(direction.getKeyStroke(), direction.getText());
}
frame.getRootPane().setActionMap(actionMap);
frame.getRootPane().setInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW, inputMap);
// setup window listener for close action
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
stop();
}
});
}
public static void main(String... args)
{
HighRes webcam = new HighRes();
webcam.start();
}
#Override
public void run()
{
try
{
grabber.setImageWidth(frameWidth);
grabber.setImageHeight(frameHeight);
grabber.start();
while (running)
{
final IplImage cvimg = grabber.grab();
if (cvimg != null)
{
// cvFlip(cvimg, cvimg, 1); // mirror
// show image on window
bufImg = cvimg.getBufferedImage();
frame.showImage(bufImg);
}
}
grabber.stop();
grabber.release();
frame.dispose();
}
catch (Exception e)
{
e.printStackTrace();
}
}
public void start()
{
new Thread(this).start();
running = true;
}
public void stop()
{
running = false;
}
private class KeyBinding extends AbstractAction {
private static final long serialVersionUID = 1L;
public KeyBinding(String text)
{
super(text);
putValue(ACTION_COMMAND_KEY, text);
}
#Override
public void actionPerformed(ActionEvent e)
{
String action = e.getActionCommand();
if (action.equals(Keys.ESCAPE.toString()) || action.equals(Keys.CTRLC.toString())) stop();
else System.out.println("Key Binding: " + action);
}
}
}
enum Keys
{
ESCAPE("Escape", KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0)),
CTRLC("Control-C", KeyStroke.getKeyStroke(KeyEvent.VK_C, KeyEvent.CTRL_DOWN_MASK)),
UP("Up", KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0)),
DOWN("Down", KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0)),
LEFT("Left", KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0)),
RIGHT("Right", KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0));
private String text;
private KeyStroke keyStroke;
Keys(String text, KeyStroke keyStroke)
{
this.text = text;
this.keyStroke = keyStroke;
}
public String getText()
{
return text;
}
public KeyStroke getKeyStroke()
{
return keyStroke;
}
#Override
public String toString()
{
return text;
}
}

You can try Java Webcam SDK library also.
SDK demo applet is available at link.

I have used JMF on a videoconference application and it worked well on two laptops: one with integrated webcam and another with an old USB webcam. It requires JMF being installed and configured before-hand, but once you're done you can access the hardware via Java code fairly easily.

You can try Marvin Framework. It provides an interface to work with cameras. Moreover, it also provides a set of real-time video processing features, like object tracking and filtering.
Take a look!
Real-time Video Processing Demo:
http://www.youtube.com/watch?v=D5mBt0kRYvk
You can use the source below. Just save a frame using MarvinImageIO.saveImage() every 5 second.
Webcam video demo:
public class SimpleVideoTest extends JFrame implements Runnable{
private MarvinVideoInterface videoAdapter;
private MarvinImage image;
private MarvinImagePanel videoPanel;
public SimpleVideoTest(){
super("Simple Video Test");
videoAdapter = new MarvinJavaCVAdapter();
videoAdapter.connect(0);
videoPanel = new MarvinImagePanel();
add(videoPanel);
new Thread(this).start();
setSize(800,600);
setVisible(true);
}
#Override
public void run() {
while(true){
// Request a video frame and set into the VideoPanel
image = videoAdapter.getFrame();
videoPanel.setImage(image);
}
}
public static void main(String[] args) {
SimpleVideoTest t = new SimpleVideoTest();
t.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
For those who just want to take a single picture:
WebcamPicture.java
public class WebcamPicture {
public static void main(String[] args) {
try{
MarvinVideoInterface videoAdapter = new MarvinJavaCVAdapter();
videoAdapter.connect(0);
MarvinImage image = videoAdapter.getFrame();
MarvinImageIO.saveImage(image, "./res/webcam_picture.jpg");
} catch(MarvinVideoInterfaceException e){
e.printStackTrace();
}
}
}

I used Webcam Capture API. You can download it from here
webcam = Webcam.getDefault();
webcam.open();
if (webcam.isOpen()) { //if web cam open
BufferedImage image = webcam.getImage();
JLabel imageLbl = new JLabel();
imageLbl.setSize(640, 480); //show captured image
imageLbl.setIcon(new ImageIcon(image));
int showConfirmDialog = JOptionPane.showConfirmDialog(null, imageLbl, "Image Viewer", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE, new ImageIcon(""));
if (showConfirmDialog == JOptionPane.YES_OPTION) {
JFileChooser chooser = new JFileChooser();
chooser.setDialogTitle("Save Image");
chooser.setFileFilter(new FileNameExtensionFilter("IMAGES ONLY", "png", "jpeg", "jpg")); //this file extentions are shown
int showSaveDialog = chooser.showSaveDialog(this);
if (showSaveDialog == 0) { //if pressed 'Save' button
String filePath = chooser.getCurrentDirectory().toString().replace("\\", "/");
String fileName = chooser.getSelectedFile().getName(); //get user entered file name to save
ImageIO.write(image, "PNG", new File(filePath + "/" + fileName + ".png"));
}
}
}

http://grack.com/downloads/school/enel619.10/report/java_media_framework.html
Using the Player with Swing
The Player can be easily used in a Swing application as well. The following code creates a Swing-based TV capture program with the video output displayed in the entire window:
import javax.media.*;
import javax.swing.*;
import java.awt.*;
import java.net.*;
import java.awt.event.*;
import javax.swing.event.*;
public class JMFTest extends JFrame {
Player _player;
JMFTest() {
addWindowListener( new WindowAdapter() {
public void windowClosing( WindowEvent e ) {
_player.stop();
_player.deallocate();
_player.close();
System.exit( 0 );
}
});
setExtent( 0, 0, 320, 260 );
JPanel panel = (JPanel)getContentPane();
panel.setLayout( new BorderLayout() );
String mediaFile = "vfw://1";
try {
MediaLocator mlr = new MediaLocator( mediaFile );
_player = Manager.createRealizedPlayer( mlr );
if (_player.getVisualComponent() != null)
panel.add("Center", _player.getVisualComponent());
if (_player.getControlPanelComponent() != null)
panel.add("South", _player.getControlPanelComponent());
}
catch (Exception e) {
System.err.println( "Got exception " + e );
}
}
public static void main(String[] args) {
JMFTest jmfTest = new JMFTest();
jmfTest.show();
}
}

Java usually doesn't like accessing hardware, so you will need a driver program of some sort, as goldenmean said. I've done this on my laptop by finding a command line program that snaps a picture. Then it's the same as goldenmean explained; you run the command line program from your java program in the takepicture() routine, and the rest of your code runs the same.
Except for the part about reading pixel values into an array, you might be better served by saving the file to BMP, which is nearly that format already, then using the standard java image libraries on it.
Using a command line program adds a dependency to your program and makes it less portable, but so was the webcam, right?

I believe the web-cam application software which comes along with the web-cam, or you native windows webcam software can be run in a batch script(windows/dos script) after turning the web cam on(i.e. if it needs an external power supply). In the bacth script , u can add appropriate delay to capture after certain time period. And keep executing the capture command in loop.
I guess this should be possible
-AD

There's a pretty nice interface for this in processing, which is kind of a pidgin java designed for graphics. It gets used in some image recognition work, such as that link.
Depending on what you need out of it, you might be able to load the video library that's used there in java, or if you're just playing around with it you might be able to get by using processing itself.

FMJ can do this, as can the supporting library it uses, LTI-CIVIL. Both are on sourceforge.

Recommand using FMJ for multimedia relatived java app.

Try using JMyron How To Use Webcam Using Java. I think using JMyron is the easiest way to access a webcam using java. I tried to use it with a 64-bit processor, but it gave me an error. It worked just fine on a 32-bit processor, though.