I have a public class AppHelper for displaying some help content using a jframe. There is an exit button on the same JFrame which on click disposes the jframe.
The ActionListener is implemented as a static nested class of the class mentioned above.
Also all the components of the help window are defined in the outer class and all of them are private and static. Also the method that shows the help window is static.
Here is some code that I have implemented:
public class AppHelper {
// helper frame
private static JFrame appHelperFrame;
// helper panel
private static JPanel appHelperPanel;
// helper pane
private static JEditorPane appHelperPane;
// exit helper button
private static JButton exitAppHelperButton;
// constraints
private static GridBagConstraints appHelperPaneCons, exitAppHelperButtonCons;
/**
set layout
*/
private static void setLayoutConstraints () {
// defines layout
}
/**
* initialize the helper elements
* #param void
* #return void
*/
public static void initializeElements () {
// initialize constraints
setLayoutConstraints();
// handler
AppHelper.AppHelperHandler appHelpHandler = new AppHelper.AppHelperHandler();
appHelperFrame = new JFrame("App Help");
appHelperPanel = new JPanel();
appHelperPanel.setLayout(new GridBagLayout());
appHelperPane = new JEditorPane();
exitAppHelperButton = new JButton("Exit");
exitAppHelperButton.addActionListener(appHelpHandler);
java.net.URL helpURL = null;
try {
helpURL = new File("AppHelp.html").toURI().toURL();
} catch (MalformedURLException ex) {
Logger.getLogger(AppHelper.class.getName()).log(Level.SEVERE, null, ex);
}
try {
appHelperPane.setPage(helpURL);
} catch (IOException ex) {
Logger.getLogger(AppHelper.class.getName()).log(Level.SEVERE, null, ex);
}
appHelperPane.setEditable(false);
appHelperFrame.add(appHelperPanel);
appHelperPanel.add(appHelperPane, appHelperPaneCons);
appHelperPanel.add(exitAppHelperButton, exitAppHelperButtonCons);
appHelperFrame.setSize(350, 400);
appHelperFrame.setResizable(false);
appHelperFrame.setVisible(true);
}
/**
* TODO
*/
public static void showAboutApp() {
//throw new UnsupportedOperationException("Not yet implemented");
}
/**
*
* Acts as the handler for the help window components
* Implement actionListener interface.
*/
private static class AppHelperHandler implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if(source == exitAppHelperButton) {
appHelperFrame.dispose();
}
}
}
}
The reason of disposing the JFrame instead of setting it invisible is that I dont want this JFrame to consume memory when this JFrame is not in use.
Now the problem is first time I click on the help button (on some other window) the JFrame is shown. Now when I click the exit button on this help window the JFrame is disposed by the handler. Next time I again click on the help button, the help window is not shown. I wanted to know if there is any error in my code or I need to do some thing else.
The javadoc of Window.dispose() states that
The Window and its subcomponents can be made displayable again by rebuilding the native resources with a subsequent call to pack or show.
And that works too, I've tried it. Just call appHelperFrame.setVisible(true) and that's all. If the window is not activated, try calling appHelperFrame.setState(Frame.NORMAL) which will acitvate it.
You only have to call your initializeElements method once though. Your showAboutApp() method should look something like this:
public static void showAboutApp() {
if (appHelperFrame == null)
initializeElements(); // This also makes the frame visible
else {
appHelperFrame.setVisible(true);
appHelperFrame.setState(Frame.NORMAL);
}
}
Final note:
If you always call this showAboutApp() from the EDT (Event Dispatching Thread) then you're good. If you call this from multiple threads, you might want to execute it in the EDT with like SwingUtilities.invokeAndwait() or SwingUtilities.invokeLater() which also ensures synchronization between multiple threads.
Related
I need some help with a simple java application which makes use of two jframe to get some input parameters. Here's a sketch of my code:
//second jframe, called when the button OK of the first frame is clicked
public class NewParamJFrame extends JFrame{
...
}
//first jframe
public class StartingJFrame extends JFrame{
private static NewParamJFrame newPFrame = null;
private JTextField gnFilePath;
private JButton btnOK;
public StartingJFrame(){
//..
initComponents();
}
private void initComponents(){
btnOK.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
try{
EventQueue.invokeAndWait(new Runnable(){
public void run() {
try {
newPFrame = new NewParamJFrame();
newPFrame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
catch(InvocationTargetException e2) {}
catch(InterruptedException e1){}
dispose();
}
}
public String getText(){
return gnFilePath.getText();
}
}
public class Main {
private static StartingJFrame begin = null;
public static void main(String[] args) {
try{
EventQueue.invokeAndWait(new Runnable(){
public void run() {
try {
begin = new StartingJFrame();
begin.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
catch(InvocationTargetException e) {}
catch(InterruptedException e1){}
String s= begin.getText();
//...use s ...
}
}
The call to getText() causes a NullPointerException. I want the main class to wait until the frames are closed but I don't know how to do. I'm using swing for the first time.
I want the main class to wait until the frames are closed but I don't
know how to do. I'm using swing for the first time.
If I understand your problem correctly, you need StartingJFrame to stay waiting until NewParamJFrame is closed and then continue its execution. If this is the case then it won't happen because JFrame doesn't support modality. But JDialog does, so you can have just one JFrame and do the parameters request in a JDialog whose parent is this JFrame.
For a better explanation about modality, take a read to How to Use Modality in Dialogs.
Also take a look to this topic: The Use of Multiple JFrames, Good/Bad Practice?
In any case you'll probably face a new problem: what should the JFrame do if the user closes/cancels the dialog withouth input any parameter? How could this JFrame know what just happened in that dialog? One approach is described in this answer. You'll see the example is about a login dialog but the problem is similar to this one: How could a dialog notify to its parent frame on how the process went?
The easiest way to wait for close without modifying the code flow is to use a modal JDialog. So you have to change your StartingJFrame class to make it a subclass of JDialog instead of JFrame, and add the following to the begin of its constructor:
super((Window)null);
setModal(true);
Then the setVisible(true); invocation on the StartingJFrame instance will wait until the dialog has been closed and hence the invokeAndWait invocation will wait too.
The call to getText() causes a NullPointerException.
Because, gnFilePath of JTextField is null.
private JTextField gnFilePath;
public String getText(){
return gnFilePath.getText();// NullPointerException is throw here.
}
To avoid NPE, you need to initialize JTextField and JButton like below.
private JTextField gnFilePath=new JTextField();
private JButton btnOK=new JButton()
Try putting this:
import java.awt.event.*;
import javax.swing.*;
public class MyWindow extends JFrame{
MyWindow(){
setSize(300, 200);
setLayout(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton b = new JButton("Close");
b.setBounds((300-80)/2, (200-30)/2, 80, 30);
//
final MyWindow frame = this;
b.addActionListener(
new ActionListener(){
#Override
public void actionPerformed(ActionEvent ev){
synchronized(frame){
frame.notify();
}
frame.setVisible(false);
frame.dispose();
}
}
);
//
getContentPane().add(b);
setVisible(true);
synchronized(this){
try{
this.wait();
}
catch(InterruptedException ex){ }
}
}
public static void main(String args[]) {
new MyWindow();
System.out.println("You are here");
}
}
The code above is checked.
Using a JDialog is probably the simplest solution, but in some cases it's desirable to have a JFrame, for example to show the window in the taskbar. Using a synchronization mechanism as suggested by Octavio is a way to achieve this, here is an alternative using a CountDownLatch blocking the main thread until the frame is closed:
public static void main(String[] args) throws Exception {
CountDownLatch latch = new CountDownLatch(1);
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
frame.setSize(300, 200);
frame.setVisible(true);
frame.addWindowListener(new WindowAdapter() {
public void windowClosed(WindowEvent e) {
latch.countDown();
}
});
});
latch.await();
System.out.println("Main thread released");
}
You can use a loop (preferably do-while loop) to put a frame on hold until the other frame closes or hides. Make sure to break the loop or increment the variable used for the loop by specific amount when the other frame is disposed or hidden. This way you can keep your StartingJFrame class to remain as a subclass of JFrame.
do {
if (changeLog.isVisible()) {
} else {
changeLog.dispose();
break;
}
} while (hold < 1);
or
do {
if (changeLog.isActive()) {
} else {
break;
}
} while (hold < 1);
The first one would require the previous frame to be hidden (JFrame.HIDE_ON_EXIT or Window.setVisible(false)) before the codes can be run. The last one would require the previous frame to be "disposed" (JFrame.DISPOSE_ON_EXIT or (subclass of JFrame).dispose(). Add any of those codes on StartingJFrame, though, since you created a NewParamJFrame in that class and have the corresponding field(s) set to private.
I need to refresh my GUI each time a function is triggered.
This is how I defined the skeleton of the GUI:
public class GUI {
private JFrame frame;
/**
* Launch the application.
*/
public static void runGui() {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
GUI window = new GUI();
window.frame.setVisible(true);
window.frame.setSize(800, 600);
window.frame.setTitle("My Title");
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public GUI() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
//CODE
}
So, the GUI.runGui() function is called in a function like:
public void myFunction()
{
//CODE
GUI.runGui();
}
The problem is the following: every time this function is called, it generates a new instance of the GUI, so I end up having multiple instances. This is not what I want, since I just need to refresh the content of the GUI that must be only one.
I believe the problem is architectural.
Is there a way to solve this?
Look at what runGui is doing: it's creating and initializing a GUI every time you call it. Pull that one time initialization code out of runGui and into another place that you run once (like the initialize method). And in runGui access a component that you want to refresh (perhaps the content pane) as:
// This needs to become an instance method (non static) in this example in
// order to access the frame
public void runGui() {
EventQueue.invokeLater(new Runnable() {
public void run() {
// Refresh your component here. Here I'm redrawing the
// content pane
frame.getContentPane().repaint();
}
});
}
frame.repaint();
This article contains some repaint examples:
https://www.programcreek.com/java-api-examples/?class=javax.swing.JFrame&method=repaint
The solution is to get the content pane from the frame and then use .repaint(). You can do the following:
JFrame frame = new JFrame("Title");
frame.getContentPane().repaint();
Class1 which is a NewJFrame Form and is also a calling class to class2, NewJFrame3 has a Jbutton component, jButton1, for which method actionPerformed has been over-ridden. I call the object with a thread. On calling, Class2, NewJFrame3, a new frame pops up. Problem is when I press the default cross of called class, NewJFrame3, button [X], both screens gets cancelled. I was not using threads before and was calling the layout method for JFrame3 with just object, but it had this problem, so i used thread but it wouldnt work.
Code of calling class (Layout is fine for this and on clicking its button JButton1, class NewJframe3’s layout pops up) :
public class NewJFrame extends javax.swing.JFrame implements ActionListener
{
public NewJFrame()
{
initComponents();
jButton1.addActionListener(this);
}
private void initComponents()
{
//layout code for JFrame1 – gives the desired layout/output
}
public void actionPerformed(ActionEvent e)
{
If(some_condition)
{
NewJFrame3 obj2 = new NewJFrame3();
Thread th1 = new Thread(obj2, "thread1");
th1.start();
}
}
public static void main(String args[])
{
java.awt.EventQueue.invokeLater(new Runnable()
{
public void run()
{
new NewJFrame().setVisible(true);
}
});
}//Main ends
}//Calling Class NewJFrame1 ends
Code for called class(same package) :
public class NewJFrame3 extends javax.swing.JFrame implements Runnable
{
public void run()
{
// System.out.println("Inside Run");
this.test();
this.setVisible(true);
}
protected void test()
{
//layout code for JFrame3 – gives the desired layout/output
}
PSVM()
{
//Main method code not relevant here, since layout function is called from run() which gets called on starting thread for this class.
}
} //Called Class NewJFrame3 end
Thanks a ton for your time!
you have to set for defaultCloseOperation, set to DISPOSE_ON_CLOSE in this case, last of JFrames to terminating an Current JVM
your current issue is default value HIDE_ON_CLOSE, then current JVM is still running, consume and increase RAM in PC
use CardLayout or JDialog with parent, and/or setModal/ ModalityTypes instead of two JFrames
I'm making a program which creates and displays graphs.
I have a class which handles a graph and implements a mouse listener (Graphstream ViewerListener).
In order to grab the events, you need to use a loop and call a pump() method until you're done.
To display the graph, the Graphstream library has a View object which extends and can be used as a regular Jpanel, just set the View object as a content pane in the JFrame.
My class works fine when used with a JFrame with no menu bar.
But when i set a JMenuBar at the JFrame, the problems start.
I call the method inside my graph class, it gets inside the loop, but the ViewerListener doesn't work, like it's not listening for events. Why?
This is my class code, unnecessary stuff omitted
public class GeneratedGraph implements ViewerListener{
public String[] getNodes(){
boolean flag=true;
startEndNodes[0]=null; startEndNodes[1]=null;
arrayposition=0;
while(flag){
System.out.println("Inside the loop");
fromViewer.pump();
try {
Thread.sleep(250);
} catch (InterruptedException e) {
e.printStackTrace();
}
if(startEndNodes[0]!=null && startEndNodes[1]!=null){
flag=false;
}
}
System.out.println("Outside the loop");
return startEndNodes;
}
public void buttonPushed(String id) { //This method fires up when you click on a node
System.out.println("Button pushed on node "+id);
startEndNodes[arrayposition]=id;
arrayposition++;
if(arrayposition>1){ arrayposition=0;}
}
}
Now, to put things into perspective, this WORKS, gets in, grabs the nodes, and exits the loop fine. (unnecessary code again omitted)
public class main extends implements ActionListener {
public static void main(String args[]){
JFrame mainFrame = new JFrame("Graph");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GeneratedGraph myGraph = new GeneratedGraph(mainFrame);
myGraph.option1(5,6); //a method which creates a graph
myGraph.show();
mainFrame.pack();
mainFrame.setVisible(true);
String s[] = myGraph.getNodes();
}
}
But when i add this, it doesn't. It just gets inside the loop and events from the ViewerListener never fire so it gets stuck.
public class main extends implements ActionListener {
public static void main(String args[]){
JFrame mainFrame = new JFrame("Graph");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JMenuBar menuBar= new JMenuBar();
mainFrame.setJMenuBar(menuBar);
JMenu algorithmMenu = new JMenu("Algorithms");
JMenuItem dijkstra = new JMenuItem("Dijkstra");
dijkstra.addActionListener(this);
dijkstra.setActionCommand("Dijkstra");
algorithmMenu.add(dijkstra);
menuBar.add(algorithmMenu);
GeneratedGraph myGraph = new GeneratedGraph(mainFrame);
myGraph.option1(5,6); //a method which creates a graph
myGraph.show();
mainFrame.pack();
mainFrame.setVisible(true);
String s[] = myGraph.getNodes();
}
}
The part that seems to break everything is this
menuBar.add(algorithmMenu);
When i comment out this particular line, it works fine.
Any ideas what might be causing the ViewerListener not to respond? It just seems so random that a JMenuBar would break it.
I Have written a listener for an IMediaReader from Xuggler.
It should show a video in a JPanel what i can add to a JFrame.
I have created this JFrame in the class main:
class Window extends JFrame {
static IMediaReader reader;
static Window main;
public static void main(String[] args) {
new Thread() {
public void run() {
reader = ToolFactory.makeReader("C:/Users/André/Desktop/Detail.wmv");
reader.addListener(new Player(IMediaViewer.Mode.AUDIO_VIDEO, main));
while (reader.readPacket() == null)
do {} while(false);
}
}.start();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
main = new Window();
}
});
}
private Window() {
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
setVisible(true);
setSize(700, 700);
}
});
}
// invoked by Player with the video panel
public void add(final JPanel videoPanel) {
add(videoPanel, BorderLayout.CENTER);
}
}
It shows the video but it only works when i resize the window manually and that is my problem. Else, it shows a small black square.
Using pack() instead of setSize() or invoke repaint doesn't help.
The Code of class Player isn't just from me. I've just changed some things:
public class Player extends MediaListenerAdapter implements IMediaListener, IMediaViewer {
private static Main main;
Player(Mode mode, Main main) {
setMode(mode);
Player.main = main;
}
#Override
public void onAddStream(IAddStreamEvent event)
{
[...]
MediaFrame frame = new MediaFrame(stream, this, main);
[...]
}
#Override
public void onVideoPicture(IVideoPictureEvent event)
{
MediaFrame frame = mFrames.get(event.getStreamIndex());
frame.setVideoImage(event.getPicture(), event.getImage());
}
static class PositionFrame extends JPanel
{
public PositionFrame(Player viewer, Main main)
{
main.add(this);
mFrames.add(this);
}
protected void adjustSize()
{
invalidate();
}
}
private class MediaFrame extends PositionFrame
{
// the video image
private BufferedImage mImage;
// the video panel
private final JPanel mVideoPanel;
// the stream
private final IStream mStream;
// the index of the stream (incase it's closed)
private final int mStreamIndex;
/**
* Construct a media frame.
*
* #param defaultCloseOperation what should Swing do if the window
* is closed. See the {#link javax.swing.WindowConstants}
* documentation for valid values.
* #param stream the stream which will appear in this frame
* #param viewer containing media viewer
*/
public MediaFrame(IStream stream,
Player viewer, Main main)
{
super(viewer, main);
// get stream and set title based it, establish a copy of the
// stream since it lives in a separate thread
mStream = stream.copyReference();
mStreamIndex = mStream.getIndex();
// the panel which shows the video image
mVideoPanel = new JPanel()
{
public void paint(Graphics graphics)
{
paintPanel((Graphics2D) graphics);
}
};
// add the videoPanel
add(mVideoPanel);
// show the frame
setVisible(true);
}
// set the video image
protected void setVideoImage(IVideoPicture picture, BufferedImage image)
{
[...]
}
protected void paintPanel(Graphics2D graphics)
{
if (mImage != null)
graphics.drawImage(mImage, 0, 0, null);
}
}
}
It is made up from the class MediaViewer
http://code.google.com/p/xuggle/source/browse/trunk/java/xuggle-xuggler/src/com/xuggle/mediatool/MediaViewer.java?r=644
EDIT: If I do it like this, it doesn't work without resizing manually.
I'm not shure if I have unterstood you right.
You have this code in two places.
pack();
setSize(700, 700);
The pack() class is wasteful since you are setting the size immediately afterwards. Also, the first time you call in your constructor you haven't even added anything yet.
Try setting the size or calling pack after you have added the video component and after you have made the frame visible.
Based on your edits, I believe the issue is that you are setting the frame visible before the component is in place. Move your setVisible and pack() calls to the end of your constructor for the Main class instead of the add() method.
Based on more edits to your question: As I mentioned in the comments, make sure you separate off the GUI code in a separate call to invokeLater to get things happening on the EDT. Therefore you need to move your IMediaReader creation and thread starting into your main() method, then after that create a new call to SwingUtilities.invokeLater that creates a new Main, class. By the way, Main is a confusing name for a class.