I have a Java program. When I run the program, it will give me a GUI which as I attached.
When I want to close it, it will prompt out a confirm dialog. If I press the Yes button, it will quit the program using System.exit().
public static void main(String args[])
{
ButtonTest app = new ButtonTest( );
app.addWindowListener(
new WindowAdapter( )
{
public void windowClosing (WindowEvent e)
{
String message = " Really Quit ? ";
String title = "Quit";
int reply = JOptionPane.showConfirmDialog(null, message, title, JOptionPane.YES_NO_OPTION);
if (reply == JOptionPane.YES_OPTION)
{
System.exit(0);
}
}
}
);
}
If I don't want to quit the program, what can I do? System.continued() ?
You Don't need the else in this case
Try setting this,
app.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE)
[Edited]
So, your code will become something like this,
public static void main(String args[]) {
ButtonTest app = new ButtonTest();
app.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
int reply = JOptionPane.showConfirmDialog(null,
"Really Quit ?", "Quit", JOptionPane.YES_NO_OPTION);
if (reply == JOptionPane.YES_OPTION)
System.exit(0);
}
});
app.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
app.setSize(640, 480);
app.setVisible(true);
}
[Explanation]
You might be thinking that why it is like that. The behaviour of windows close button for JFrame, unlike Frame,is to hide the window. Therefore, it will hide/close the window anyway. But when you specify that it must also exit the program, when the user click yes. Then, besides closing the window, it also exits the program. And when user clicks no, it does nothing but closes the window anyway. Hence, you must tell it explicitly that DO_NOTHING_ON_CLOSE.
[Docs]
Unlike a Frame, a JFrame has some notion of how to respond when the
user attempts to close the window. The default behavior is to simply
hide the JFrame when the user closes the window. To change the default
behavior, you invoke the method setDefaultCloseOperation(int). To make
the JFrame behave the same as a Frame instance, use
setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE).
Ref: JFrame docs
If you will ask me, I will go with, on YES SELECTION instead of abruptly closing my Application with System.exit(0), I will choose the gracious way of closing my Application, by using frameObject.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) and on NO SELECTION , I will go for frameObject.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE). Here is one sample program for your help :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ApplicationCloseExample
{
private void displayGUI()
{
final JFrame frame = new JFrame("Application Close Example");
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent we)
{
int result = JOptionPane.showConfirmDialog(
frame, "Do you want to Exit ?"
, "Exit Confirmation : ", JOptionPane.YES_NO_OPTION);
if (result == JOptionPane.YES_OPTION)
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
else if (result == JOptionPane.NO_OPTION)
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
}
});
frame.setSize(300, 300);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new ApplicationCloseExample().displayGUI();
}
});
}
}
If you want the program to continue when you press NO, place the rest of your code in else block or call the function where you have placed the rest of your code.
Removing else block is also an option if you don't want to place any action on the NO button because the JOptionPane.showConfirmDialog() will close anyways. You can continue with rest of your code after the if statement.
FYI- There is no System.continue(). The program pretty much does that on it's own.
You can add an else block. if you want to run the main method again (which I assume you do) it should look like this. You should have some method which you run if the user chooses no, whether it is the main method main(null) or another method.
public static void main(String args[])
{
ButtonTest app = new ButtonTest( );
app.addWindowListener(
new WindowAdapter( )
{
public void windowClosing (WindowEvent e)
{
String message = " Really Quit ? ";
String title = "Quit";
int reply = JOptionPane.showConfirmDialog(null, message, title, JOptionPane.YES_NO_OPTION);
if (reply == JOptionPane.YES_OPTION)
{
System.exit(0);
}
else
{
//whatever you plan on running instead here, instead of quitting,
//main(null) to run the main method, or put another method if you want
}
}
}
);
}
Related
I'm having a slight issue, and I can't figure it out.
I want for my code to check if the email and password matches and then close the window. This the action:
btnLogin.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
boolean status = Email_Verification.email_validation(email_text.getText().toString().trim());
if (status) {
lbl_inco_email.setText(null);
} else {
lbl_inco_email.setText("Please enter a valid email");
}
boolean stat = Password_Verification.password_validation(password_Field.getPassword().toString());
if (stat) {
lbl_inco_pwd.setText(null);
} else {
lbl_inco_pwd.setText("Please enter a valid Password");
}
/* Exit and redirect to the main application if the email/pwd matches the database */
/** MAIN__WINDOW __EXIT__ONCLICK__ = new MAIN__WINDOW();
__EXIT__ONCLICK__.setVisible(true); */
}
});
I am going to assume you have an issue with opening a new frame and disposing of the login frame, because if you have an issue with user validation there isn't enough information for any of us to actually help.
Also, please read this concerning the use of multiple JFrames. The Use of Multiple JFrames: Good or Bad Practice?
Now for the code section...
Once user validation is done, you need to create an instance of your main window and make it visible. After that you can close the first JFrame.
Your actionPerformed would look something like this:
btnLogin.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// Let's assume you have a boolean variable that handles user validation
//for simplicity...
if(userVerified) {
// In this example let's call the main application window MainFrame
MainFrame mF = new MainFrame();
// Set it to visible
mF.setVisible(true);
mF.setLocationRelativeTo(null);
// Now you can close the first JFrame
this.dispose();
}
}
});
There´s any methods to set the default close operation on PApplet?
I tried to embed the PApplet in a JFrame, but it wont init correctly, i need to set the window to dont close at exit, in JFrame i can just set it to DO_NOTHING_ON_CLOSE, dont know how to do in a PApplet. I'm implementing a confirm exit dialog, and i just want to close only when i confirm.
PApplet already have a frame, but it's not a JFrame, so i can´t just call setDefaultCloseOpreation.
I´ve added an window listener to get the window closing action:
//frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent ev) {
int confirm = JOptionPane.showOptionDialog(frame,
"Want to save all unsaved data?",
"Exit confirmation", JOptionPane.YES_NO_CANCEL_OPTION,
JOptionPane.QUESTION_MESSAGE, null, null, null);
switch(confirm) {
case JOptionPane.YES_OPTION:
System.out.println("Data saved, closing...");
break;
case JOptionPane.NO_OPTION:
System.out.println("Data lost, closing...");
break;
case JOptionPane.CANCEL_OPTION:
System.out.println("Close canceled.");
break;
}
}
});
In the cancel option i want to close this dialog and keep open the application, this way without "do nothing on close" every option i choose close the application.
The API documentation of PApplet at http://processing.org/reference/javadoc/core/processing/core/PApplet.html shows how a PApplet may be embedded into a Frame, and explicitly states that "...there's nothing to prevent you from embedding a PApplet into a JFrame". When you use a pattern according to the ExampleFrame shown there (but extending JFrame), you should be able to set the desired default close operation and attach your listener.
A while back I ran into this same problem. I'm not sure that this code solved it, but I think it helped? There are some window listeners already there, this code removes them. I also dimly recall having to run it after a few frames because they hadn't been initialized or something immediately after the program starts or something. You can give it a shot, anyway:
WindowListener[] wls = frame.getWindowListeners();
println("Removing " + wls.length + " window listeners.");
for (int i = 0; i < wls.length; i++) {
frame.removeWindowListener(wls[i]);
}
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent we)
{
checkExit();
}
}
);
Solved this problem embedding the PApplet on JFrame, but as the example show in the processing documentation is very simple, it don´t work as expected.
Here´s the code working:
public class Application extends PApplet {
public void setup() {
size(600, 480, JAVA2D);
}
public void draw() {
background(255);
}
public void closeApplication() {
exit();
}
public static void main(String _args[]) {
final JFrame frame = new JFrame("Embbed Applet");
frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
JPanel panel = new JPanel();
final Application applet = new Application();
applet.init();
panel.add(applet);
frame.add(panel);
frame.setSize(600, 510);
frame.setResizable(false);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent ev) {
int confirm = JOptionPane.showOptionDialog(frame,
"Want to save all unsaved data?",
"Exit confirmation", JOptionPane.YES_NO_CANCEL_OPTION,
JOptionPane.QUESTION_MESSAGE, null, null, null);
switch(confirm) {
case JOptionPane.YES_OPTION:
// Save data
applet.closeApplication();
System.exit(0);
break;
case JOptionPane.NO_OPTION:
applet.closeApplication();
System.exit(0);
break;
case JOptionPane.CANCEL_OPTION:
// Do nothing
break;
}
}
});
frame.setVisible(true);
}
I'm using this code to confirm the user whether wants to quit or not when he CLICKS THE RED CROSS CLOSE BUTTON OF JFrame (right upper corner)
Object[] options = {"Quit, My Computing Fellow", "No, I want to Work more"};
int Answer = JOptionPane.showOptionDialog(null, "What would you like to do? ","Quit:Continue", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
null, options,options[1]);
if(Answer == JOptionPane.YES_OPTION){
System.exit(0);
}
else if (Answer == JOptionPane.CANCEL_OPTION) {
return;
}
but the problem is if the user clicks CANCEL_OPTION the Frame Closes at all, but i want the user to still open the Frame and not allow the Frame to close. Guide me If I'm doing the blunder or something else?
just do this:
setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
You can try something like this:
import javax.swing.*;
import java.awt.event.*;
public class MyFrame extends JFrame
{
public MyFrame()
{
setTitle("Close Me");
setSize(200,200);
setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
addWindowListener(new WindowAdapter()
{
#Override
public void windowClosing(WindowEvent evt)
{
Object[] options = {"Quit, My Computing Fellow", "No, I want to Work more"};
int answer = JOptionPane.showOptionDialog(MyFrame.this, "What would you like to do? ","Quit:Continue", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
null, options,options[1]);
if(answer == JOptionPane.YES_OPTION)
{
System.exit(0);
}
}
});
}
public static void main(String st[])
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
MyFrame mf = new MyFrame();
mf.setVisible(true);
}
});
}
}
As a side note I would suggest you to stick with java naming conventions. For example the variable name should never start with capital letter, class name should always start with capital letter .. And many more. Have a look at here Code Conventions for the Java Programming Language
try something like this:
{
...
yourFrame.setDefaultCloseOperation(close());
...
}
private int close() {
if(yourCondition)
return JFrame.DO_NOTHING_ON_CLOSE;
else
return JFrame.EXIT_ON_CLOSE;
}
I have a Real blunder
Object[] options = {"Quit, My Computing Fellow", "No, I want to Work more"};
int Answer = JOptionPane.showOptionDialog(null, "What would you like to do?","Quit:Continue", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE,
null, options,options[1]);
if(Answer == JOptionPane.YES_OPTION){
System.exit(0);
}
else if (Answer == JOptionPane.CANCEL_OPTION) {
return;
}
It was clear that I have two Options i.e YES_NO_OPTION and I was calling the CANCEL_OPTION that was a real blunder so, the else-if should be changed to:
else if (Answer == JOptionPane.NO_OPTION) {
this.setDefaultCloseOperation(myclassreference.DO_NOTHING_ON_CLOSE);
}
after this; its bingo !!! I've done!
I have a Java Program containing a class Application inheriting from JFrame.
I want to display a message which asks the user if he wants to exit the program upon clicking the X button at the top right of the window.
This is my code so far:
I got this code from a tutorial I found online. I coded the WindowClosing event handler myself. However, I have trouble registering the window listener (addWindowListener). It is telling me that WindowAdapter is abstract and cannot be instantiated.
How can I solve this problem please?
Basically, you got it almost correct. There are a few things not put together correctly and a typo.
First remove your WindowClosing method (it's window, not Window)
Then replace your addWindowListener(new WindowAdapter()); with the code below
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
int confirmed = JOptionPane.showConfirmDialog(null,
"Are you sure you want to exit the program?", "Exit Program Message Box",
JOptionPane.YES_NO_OPTION);
if (confirmed == JOptionPane.YES_OPTION) {
dispose();
}
}
});
i got this in two minutes coding....
First is set the j frame default closing event in Exit_on_close. Second create a class called "Window Closing Event Handler" and then call it in the i nit stage.
private void WindowClosingEventHandler(){ addWindowListener(new WindowAdapter() { #Override public void windowClosing(WindowEvent e) { int confirmed = JOptionPane.showConfirmDialog(null, "Are you sure you want to exit this application?", "Exit Program Message Box",JOptionPane.YES_NO_OPTION);
if (confirmed == JOptionPane.YES_OPTION) {
try{
String login=txtuserid.getText();
Connection conn = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/repair", "root", "");
Statement st = conn.createStatement();
String update = "UPDATE user set User_Status=0 where UserID='"+ login +"'";
st.executeUpdate(update);
dispose();
Login2 dialog = new Login2(new javax.swing.JFrame(), true);
dialog.setVisible(true);
}catch(SQLException | HeadlessException q){
JOptionPane.showMessageDialog(null, q);
}
System.exit(0);
}
else{
setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
}
}
});
}
Ok trying again.
You cannot create a new WindowAdapter because WindowAdapter is abstract. Abstract classes cannot be instantiated. You would need to create a subclass of WindowAdapter and implement its abstract methods as public.
http://docs.oracle.com/javase/7/docs/api/java/awt/event/WindowAdapter.html
I want to have my application react to barcodes being scanned to trigger button presses. For example the user could scan the ((PRINT)) barcode to activate the print button.
The barcodes will just be treated as if the user had entered some text. I am not sure if the scanners will be set up to append an enter or a tab or nothing on the end, so I don't want to make an assumption on that basis.
The application is a Java/Swing application.
I have looked at keybindings/action maps and the like, but they seem to be focussed on key chords/single key entries. I need it to not trigger the binding until the whole string is entered.
The tricky bit is that this should work wherever the user is focussed in the screen. They will not normally enter ( characters, so some kind of trigger on that might work. I am not sure how to handle the rest of the string though.
Edit: Apologies if it wasn't clear in the question, but the barcode scanner isn't anything "special" to the application, it's just like another keyboard. So the user won't be typing in (print), but effectively that is what the barcode scanner will be doing, if that makes sense.
So there are only two ways to trigger the print: pressing the button, or "typing" the string (print). The tricky part is that the user can be focussed anywhere on the application. I am only worried about if the application has focus as a whole, not which field the user is focussed on. The particular screen in question has checkbuttons and left/right selectors on it, so the user isn't necessarily going to be typing in to a field.
I had a problem just like yours, and created a project (currently proof of concept with some problems) to make barcode handling in swing easier.
It is based in the fact that the barcode readers emulate a keyboard but differently to humans they "type" with a constant timing. It will basically allow you to listen to "barcode read" events.
The project location: https://github.com/hablutzel1/swingbarcodelistener
Demo usage:
public class SimpleTest extends JFrame {
public SimpleTest() throws HeadlessException {
// start of listening for barcode events
Toolkit.getDefaultToolkit().addAWTEventListener(new BarcodeAwareAWTEventListener(new BarcodeCapturedListener() {
#Override
public void barcodeCaptured(String barcode) {
JOptionPane.showMessageDialog(SimpleTest.this, "barcode captured: " + barcode);
}
}), AWTEvent.KEY_EVENT_MASK);
// end of listening for barcode events
getContentPane().setLayout(new FlowLayout());
getContentPane().add(new JLabel("Capture barcode demo"));
getContentPane().add(new JTextField(25));
}
public static void main(String[] args) {
SimpleTest simpleTest = new SimpleTest();
simpleTest.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
simpleTest.setVisible(true);
simpleTest.pack();
}
}
It has some problems now but as a starting point I think it is ok, if you have time to improve it it would be great.
Correct me if I missunderstood, but it sounds like you have a barcode-scanner which will enter text into a field. But you want to be alerted when the text in the field equals something (so an action can take place) regardless of how it was entered (by barcode scanner or key press).
I'd recommend using a DocumentListener to alert you of changes to the text field - this should work with both of your requirements.
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class TempProject extends Box{
public TempProject(){
super(BoxLayout.Y_AXIS);
final JTextArea ta = new JTextArea();
ta.getDocument().addDocumentListener(new DocumentListener(){
#Override
public void changedUpdate(DocumentEvent arg0) {
doSomething();
}
#Override
public void insertUpdate(DocumentEvent arg0) {
doSomething();
}
#Override
public void removeUpdate(DocumentEvent arg0) {
doSomething();
}
public void doSomething(){
if(ta.getText().equalsIgnoreCase("print")){
System.out.println("Printing...");
//Need to clear text in a separate swing thread
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
ta.setText("");
}});
}
}
});
add(ta);
}
public static void main(String args[])
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setContentPane(new TempProject());
frame.setPreferredSize(new Dimension(500, 400));
frame.pack();
frame.setVisible(true);
}
});
}
}
I do not completely understand the question, and this is a bit too long to put in a comment. As far as I understood it, you have a Swing application and a bar-code scanner which has 3 different ways to trigger the same operation
User enters some text ("print") in the UI and this triggers the print action
The UI has a print button which can be pressed by the user and this triggers the print action
User can scan a "print" bar code and this triggers the print action
The part I do not understand is why the scanning of the bar code, which should trigger the print action, has anything to do with the UI-part where the user can input text.
I assume the scanning of the barcodes happens on another thread then the Event Dispatch Thread. Once you scanned a barcode and parsed it, you need to trigger the "print" action. You can do this directly without bothering going through the UI.
This is my approach. It's working. Just get the miliseconds for ensure doesn't read twice. Just add a Key Listener (implemented in the same JFrame).
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
logger().info("keytyped" + e.getKeyChar() + " code "+e.getKeyCode());
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
logger().info("all keys " + keyspressed);
return;
}
// will not last more than a second...
if (keyspressed == null || System.currentTimeMillis() - currentTimeMillis > 1000) {
keyspressed = e.getKeyChar()+"";
currentTimeMillis = System.currentTimeMillis();
} else {
keyspressed = keyspressed + e.getKeyChar();
currentTimeMillis = System.currentTimeMillis();
}
}
private String keyspressed = null;
private long currentTimeMillis = System.currentTimeMillis();