Error when cancel the showInputDialog

Question

I want to create a input dialog box when new record is created and save the user input as input into the file.

Here is the code :

String input = JOptionPane.showInputDialog(null, "Enter name :  ", "New Record!", 1);                //This to let user input name
    try
    {
        JOptionPane.showMessageDialog(null, "Thanks for playing.", "Thanks", 1);            //Show this dialog after user input
        HighestScoreFile.HighestScoreFile(input, hours, minutes, seconds, click);                 //Store the data into a file, the `method` is in another class.
    }
    catch(IOException ex){}

When there is no user input or any input, the OK button work fine, but if I click the cancelbutton, it returns these errors :

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at HighestScoreFile.HighestScoreFile(HighestScoreFile.java:22)
    at MemoryGame$ButtonListener.actionPerformed(MemoryGame.java:329)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

How can I solve it?

Answer 1

String input = ....
if (input!=null) { ...

Answer 2

If the user clicks on "cancel", input will be null.

You should enter the try block only if the user clicks on "ok" or you should add an if to check if input is null before trying to use it!

Now, you can actually disable the cancel button with

JOptionPane.showInputDialog(null, "Enter name :  ", "New Record!", JOptionPane.OK_OPTION);

or checking if the user clicked on cancel with

if (input == null){
    // Do something
} else {
    try {
    JOptionPane.showMessageDialog(null, "Thanks for playing.", "Thanks", 1);
    HighestScoreFile.HighestScoreFile(input, hours, minutes, seconds, click);
    } catch(IOException ex){}
}