title: Error when cancel the showInputDialog
body: <p>I want to create a input dialog box when new record is created and save the user input as <code>input</code> into the file.</p>
  
  <p>Here is the code : </p>
  
  <pre><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){}
  </code></pre>
  
  <p>When there is no user input or any input, the <code>OK</code> button work fine, but if I click the <code>cancel</code>button, it returns these errors :</p>
  
  <pre><code>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)
  </code></pre>
  
  <p>How can I solve it?</p>