How to close a Java Swing application from the code

Question

What is the proper way to terminate a Swing application from the code  and what are the pitfalls   I d tried to close my application automatically after a timer fires  But just calling dispose   on the JFrame didn t do the trick - the window vanished but the application did not terminate  However when closing the window with the close button  the application does terminate  What should I do

User · Answer

I guess a EXIT ON CLOSE  frame setDefaultCloseOperation JFrame EXIT ON CLOSE     before System exit 0  is better since you can write a Window Listener to make some cleaning operations before actually leaving the app   That window listener allows you to defined   public void windowClosing WindowEvent e        displayMessage  WindowListener method called  windowClosing           A pause so user can see the message before       the window actually closes      ActionListener task   new ActionListener             boolean alreadyDisposed   false          public void actionPerformed ActionEvent e                if  frame isDisplayable                      alreadyDisposed   true                  frame dispose                                       Timer timer   new Timer 500  task     fire every half second     timer setInitialDelay 2000            first delay 2 seconds     timer setRepeats false       timer start       public void windowClosed WindowEvent e          This will only be seen on standard output      displayMessage  WindowListener method called  windowClosed

User · Answer

In response to other comments  DISPOSE ON CLOSE does not seem to properly exit the application - it only destroys the window  but the application will continue running  If you want to terminate the application use EXIT ON CLOSE

User · Answer

I think  the idea is here the WindowListener - you can add any code there that you d like to run before the thing shuts down

User · Answer

Your JFrame default close action can be set to  DISPOSE ON CLOSE  instead of EXIT ON CLOSE  why people keep using EXIT ON CLOSE is beyond me    If you have any undisposed windows or non-daemon threads  your application will not terminate  This should be considered a error  and solving it with System exit is a very bad idea    The most common culprits are java util Timer and a custom Thread you ve created  Both should be set to daemon or must be explicitly killed   If you want to check for all active frames  you can use Frame getFrames    If all Windows Frames are disposed of  then use a debugger to check for any non-daemon threads that are still running

User · Answer

If I understand you correctly you want to close the application even if the user did not click on the close button  You will need to register WindowEvents maybe with addWindowListener   or enableEvents   whichever suits your needs better   You can then invoke the event with a call to processWindowEvent    Here is a sample code that will create a JFrame  wait 5 seconds and close the JFrame without user interaction   import javax swing    import java awt    import java awt event     public class ClosingFrame extends JFrame implements WindowListener   public ClosingFrame        super  A Frame        setSize 400  400                 in case the user closes the window         setDefaultCloseOperation JFrame EXIT ON CLOSE               setVisible true                 enables Window Events on this Component             this addWindowListener this                  start a timer     Thread t   new Timer                t start           public void windowOpened WindowEvent e    public void windowClosing WindowEvent e           the event that we are interested in public void windowClosed WindowEvent e       System exit 0      public void windowIconified WindowEvent e    public void windowDeiconified WindowEvent e    public void windowActivated WindowEvent e    public void windowDeactivated WindowEvent e           a simple timer      class Timer extends Thread             int time   10             public void run         while time--  gt  0          System out println  Still Waiting     time                  try                   sleep 500                                        catch InterruptedException e                                System out println  About to close          close the frame             ClosingFrame this processWindowEvent                   new WindowEvent                         ClosingFrame this  WindowEvent WINDOW CLOSED                              instantiate the Frame public static void main String args               new ClosingFrame               As you can see  the processWindowEvent   method causes the WindowClosed event to be fired where you have an oportunity to do some clean up code if you require before closing the application

User · Answer

Try   System exit 0     Crude  but effective

User · Answer

If I understand you correctly you want to close the application even if the user did not click on the close button  You will need to register WindowEvents maybe with addWindowListener   or enableEvents   whichever suits your needs better   You can then invoke the event with a call to processWindowEvent    Here is a sample code that will create a JFrame  wait 5 seconds and close the JFrame without user interaction   import javax swing    import java awt    import java awt event     public class ClosingFrame extends JFrame implements WindowListener   public ClosingFrame        super  A Frame        setSize 400  400                 in case the user closes the window         setDefaultCloseOperation JFrame EXIT ON CLOSE               setVisible true                 enables Window Events on this Component             this addWindowListener this                  start a timer     Thread t   new Timer                t start           public void windowOpened WindowEvent e    public void windowClosing WindowEvent e           the event that we are interested in public void windowClosed WindowEvent e       System exit 0      public void windowIconified WindowEvent e    public void windowDeiconified WindowEvent e    public void windowActivated WindowEvent e    public void windowDeactivated WindowEvent e           a simple timer      class Timer extends Thread             int time   10             public void run         while time--  gt  0          System out println  Still Waiting     time                  try                   sleep 500                                        catch InterruptedException e                                System out println  About to close          close the frame             ClosingFrame this processWindowEvent                   new WindowEvent                         ClosingFrame this  WindowEvent WINDOW CLOSED                              instantiate the Frame public static void main String args               new ClosingFrame               As you can see  the processWindowEvent   method causes the WindowClosed event to be fired where you have an oportunity to do some clean up code if you require before closing the application

User · Answer

May be the safe way is something like       private JButton btnExit              btnExit   new JButton  Quit              btnExit addActionListener new ActionListener             public void actionPerformed ActionEvent e               Container frame   btnExit getParent                do                  frame   frame getParent                 while    frame instanceof JFrame                                                        JFrame  frame  dispose

User · Answer

Take a look at the Oracle Documentation   Starting from JDK 1 4 an Application terminates if    There are no displayable AWT or Swing components  There are no native events in the native event queue  There are no AWT events in java EventQueues    Cornercases   The document states that some packages create displayable components without releasing them A program which calls Toolkit getDefaultToolkit   won t terminate  is among others given as an example   Also other Processes can keep AWT alive when they  for what ever reason  are sending events into the native event queue   Also I noticed that on some Systems it takes a coupple of seconds before the Application actually terminates

User · Answer

Your JFrame default close action can be set to  DISPOSE ON CLOSE  instead of EXIT ON CLOSE  why people keep using EXIT ON CLOSE is beyond me    If you have any undisposed windows or non-daemon threads  your application will not terminate  This should be considered a error  and solving it with System exit is a very bad idea    The most common culprits are java util Timer and a custom Thread you ve created  Both should be set to daemon or must be explicitly killed   If you want to check for all active frames  you can use Frame getFrames    If all Windows Frames are disposed of  then use a debugger to check for any non-daemon threads that are still running

User · Answer

Your JFrame default close action can be set to  DISPOSE ON CLOSE  instead of EXIT ON CLOSE  why people keep using EXIT ON CLOSE is beyond me    If you have any undisposed windows or non-daemon threads  your application will not terminate  This should be considered a error  and solving it with System exit is a very bad idea    The most common culprits are java util Timer and a custom Thread you ve created  Both should be set to daemon or must be explicitly killed   If you want to check for all active frames  you can use Frame getFrames    If all Windows Frames are disposed of  then use a debugger to check for any non-daemon threads that are still running

User · Answer

Take a look at the Oracle Documentation   Starting from JDK 1 4 an Application terminates if    There are no displayable AWT or Swing components  There are no native events in the native event queue  There are no AWT events in java EventQueues    Cornercases   The document states that some packages create displayable components without releasing them A program which calls Toolkit getDefaultToolkit   won t terminate  is among others given as an example   Also other Processes can keep AWT alive when they  for what ever reason  are sending events into the native event queue   Also I noticed that on some Systems it takes a coupple of seconds before the Application actually terminates

User · Answer

May be the safe way is something like       private JButton btnExit              btnExit   new JButton  Quit              btnExit addActionListener new ActionListener             public void actionPerformed ActionEvent e               Container frame   btnExit getParent                do                  frame   frame getParent                 while    frame instanceof JFrame                                                        JFrame  frame  dispose

User · Answer

Try   System exit 0     Crude  but effective

User · Answer

If I understand you correctly you want to close the application even if the user did not click on the close button  You will need to register WindowEvents maybe with addWindowListener   or enableEvents   whichever suits your needs better   You can then invoke the event with a call to processWindowEvent    Here is a sample code that will create a JFrame  wait 5 seconds and close the JFrame without user interaction   import javax swing    import java awt    import java awt event     public class ClosingFrame extends JFrame implements WindowListener   public ClosingFrame        super  A Frame        setSize 400  400                 in case the user closes the window         setDefaultCloseOperation JFrame EXIT ON CLOSE               setVisible true                 enables Window Events on this Component             this addWindowListener this                  start a timer     Thread t   new Timer                t start           public void windowOpened WindowEvent e    public void windowClosing WindowEvent e           the event that we are interested in public void windowClosed WindowEvent e       System exit 0      public void windowIconified WindowEvent e    public void windowDeiconified WindowEvent e    public void windowActivated WindowEvent e    public void windowDeactivated WindowEvent e           a simple timer      class Timer extends Thread             int time   10             public void run         while time--  gt  0          System out println  Still Waiting     time                  try                   sleep 500                                        catch InterruptedException e                                System out println  About to close          close the frame             ClosingFrame this processWindowEvent                   new WindowEvent                         ClosingFrame this  WindowEvent WINDOW CLOSED                              instantiate the Frame public static void main String args               new ClosingFrame               As you can see  the processWindowEvent   method causes the WindowClosed event to be fired where you have an oportunity to do some clean up code if you require before closing the application

User · Answer

Try   System exit 0     Crude  but effective

User · Answer

Try   System exit 0     Crude  but effective

User · Answer

I guess a EXIT ON CLOSE  frame setDefaultCloseOperation JFrame EXIT ON CLOSE     before System exit 0  is better since you can write a Window Listener to make some cleaning operations before actually leaving the app   That window listener allows you to defined   public void windowClosing WindowEvent e        displayMessage  WindowListener method called  windowClosing           A pause so user can see the message before       the window actually closes      ActionListener task   new ActionListener             boolean alreadyDisposed   false          public void actionPerformed ActionEvent e                if  frame isDisplayable                      alreadyDisposed   true                  frame dispose                                       Timer timer   new Timer 500  task     fire every half second     timer setInitialDelay 2000            first delay 2 seconds     timer setRepeats false       timer start       public void windowClosed WindowEvent e          This will only be seen on standard output      displayMessage  WindowListener method called  windowClosed

User · Answer

I guess a EXIT ON CLOSE  frame setDefaultCloseOperation JFrame EXIT ON CLOSE     before System exit 0  is better since you can write a Window Listener to make some cleaning operations before actually leaving the app   That window listener allows you to defined   public void windowClosing WindowEvent e        displayMessage  WindowListener method called  windowClosing           A pause so user can see the message before       the window actually closes      ActionListener task   new ActionListener             boolean alreadyDisposed   false          public void actionPerformed ActionEvent e                if  frame isDisplayable                      alreadyDisposed   true                  frame dispose                                       Timer timer   new Timer 500  task     fire every half second     timer setInitialDelay 2000            first delay 2 seconds     timer setRepeats false       timer start       public void windowClosed WindowEvent e          This will only be seen on standard output      displayMessage  WindowListener method called  windowClosed

User · Answer

In response to other comments  DISPOSE ON CLOSE does not seem to properly exit the application - it only destroys the window  but the application will continue running  If you want to terminate the application use EXIT ON CLOSE

User · Answer

I guess a EXIT ON CLOSE  frame setDefaultCloseOperation JFrame EXIT ON CLOSE     before System exit 0  is better since you can write a Window Listener to make some cleaning operations before actually leaving the app   That window listener allows you to defined   public void windowClosing WindowEvent e        displayMessage  WindowListener method called  windowClosing           A pause so user can see the message before       the window actually closes      ActionListener task   new ActionListener             boolean alreadyDisposed   false          public void actionPerformed ActionEvent e                if  frame isDisplayable                      alreadyDisposed   true                  frame dispose                                       Timer timer   new Timer 500  task     fire every half second     timer setInitialDelay 2000            first delay 2 seconds     timer setRepeats false       timer start       public void windowClosed WindowEvent e          This will only be seen on standard output      displayMessage  WindowListener method called  windowClosed

User · Answer

The following program includes code that will terminate a program lacking extraneous threads without explicitly calling System exit     In order to apply this example to applications using threads listeners timers etc  one need only insert cleanup code requesting  and  if applicable  awaiting  their termination before the WindowEvent is manually initiated within actionPerformed      For those who wish to copy paste code capable of running exactly as shown  a slightly-ugly but otherwise irrelevant main method is included at the end   public class CloseExample extends JFrame implements ActionListener        private JButton turnOffButton       private void addStuff             setDefaultCloseOperation DISPOSE ON CLOSE           turnOffButton   new JButton  Exit            turnOffButton addActionListener this           this add turnOffButton              public void actionPerformed ActionEvent quitEvent               Iterate through and close all timers  threads  etc here            this processWindowEvent                  new WindowEvent                        this  WindowEvent WINDOW CLOSING               public CloseExample             super  Close Me             addStuff               public static void main String   args            java awt EventQueue invokeLater new Runnable                 public void run                     CloseExample cTW   new CloseExample                    cTW setSize 200  100                   cTW setLocation 300 300                   cTW setVisible true

User · Answer

The following program includes code that will terminate a program lacking extraneous threads without explicitly calling System exit     In order to apply this example to applications using threads listeners timers etc  one need only insert cleanup code requesting  and  if applicable  awaiting  their termination before the WindowEvent is manually initiated within actionPerformed      For those who wish to copy paste code capable of running exactly as shown  a slightly-ugly but otherwise irrelevant main method is included at the end   public class CloseExample extends JFrame implements ActionListener        private JButton turnOffButton       private void addStuff             setDefaultCloseOperation DISPOSE ON CLOSE           turnOffButton   new JButton  Exit            turnOffButton addActionListener this           this add turnOffButton              public void actionPerformed ActionEvent quitEvent               Iterate through and close all timers  threads  etc here            this processWindowEvent                  new WindowEvent                        this  WindowEvent WINDOW CLOSING               public CloseExample             super  Close Me             addStuff               public static void main String   args            java awt EventQueue invokeLater new Runnable                 public void run                     CloseExample cTW   new CloseExample                    cTW setSize 200  100                   cTW setLocation 300 300                   cTW setVisible true

User · Answer

I think  the idea is here the WindowListener - you can add any code there that you d like to run before the thing shuts down

User · Answer

Your JFrame default close action can be set to  DISPOSE ON CLOSE  instead of EXIT ON CLOSE  why people keep using EXIT ON CLOSE is beyond me    If you have any undisposed windows or non-daemon threads  your application will not terminate  This should be considered a error  and solving it with System exit is a very bad idea    The most common culprits are java util Timer and a custom Thread you ve created  Both should be set to daemon or must be explicitly killed   If you want to check for all active frames  you can use Frame getFrames    If all Windows Frames are disposed of  then use a debugger to check for any non-daemon threads that are still running

User · Answer

If I understand you correctly you want to close the application even if the user did not click on the close button  You will need to register WindowEvents maybe with addWindowListener   or enableEvents   whichever suits your needs better   You can then invoke the event with a call to processWindowEvent    Here is a sample code that will create a JFrame  wait 5 seconds and close the JFrame without user interaction   import javax swing    import java awt    import java awt event     public class ClosingFrame extends JFrame implements WindowListener   public ClosingFrame        super  A Frame        setSize 400  400                 in case the user closes the window         setDefaultCloseOperation JFrame EXIT ON CLOSE               setVisible true                 enables Window Events on this Component             this addWindowListener this                  start a timer     Thread t   new Timer                t start           public void windowOpened WindowEvent e    public void windowClosing WindowEvent e           the event that we are interested in public void windowClosed WindowEvent e       System exit 0      public void windowIconified WindowEvent e    public void windowDeiconified WindowEvent e    public void windowActivated WindowEvent e    public void windowDeactivated WindowEvent e           a simple timer      class Timer extends Thread             int time   10             public void run         while time--  gt  0          System out println  Still Waiting     time                  try                   sleep 500                                        catch InterruptedException e                                System out println  About to close          close the frame             ClosingFrame this processWindowEvent                   new WindowEvent                         ClosingFrame this  WindowEvent WINDOW CLOSED                              instantiate the Frame public static void main String args               new ClosingFrame               As you can see  the processWindowEvent   method causes the WindowClosed event to be fired where you have an oportunity to do some clean up code if you require before closing the application

[java] How to close a Java Swing application from the code

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