title: Class.getResource() returns null
body: <p>I am trying to display pictures on the JPanel but I keep getting the error :</p>
  
  <blockquote>
    <p>java.lang.IllegalArgumentException: input == null!</p>
  </blockquote>
  
  <p>I don't understand what is happening.</p>
  
  <p>Here is the code I am using:</p>
  
  <pre><code>public void actionPerformed(ActionEvent e) {
      try {
          Image image=ImageIO.read(getClass().getResource("img/" +num.getText()+".jpg"));
  
          Image resized = image.getScaledInstance(200, 200, 100);
          pictureFrame.setIcon(new ImageIcon(resized));
      } catch (Exception ex){
          ex.printStackTrace();
      }
  }
  </code></pre>
  
  <p>This just leads to me getting the error!</p>
  
  <p>Stack trace produces the following:</p>
  
  <pre><code>Java.lang.IllegalArgumentException: input == null!
      at javax.imageio.ImageIO.read(ImageIO.java:1362)
      at work.Item.actionPerformed(Item.java:96)
      at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
      at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
      at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
      at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
      at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
      at java.awt.Component.processMouseEvent(Component.java:6297)
      at javax.swing.JComponent.processMouseEvent(JComponent.java:3275)
      at java.awt.Component.processEvent(Component.java:6062)
      at java.awt.Container.processEvent(Container.java:2039)
      at java.awt.Component.dispatchEventImpl(Component.java:4660)
      at java.awt.Container.dispatchEventImpl(Container.java:2097)
      at java.awt.Component.dispatchEvent(Component.java:4488)
      at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4575)
      at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4236)
      at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4166)
      at java.awt.Container.dispatchEventImpl(Container.java:2083)
      at java.awt.Window.dispatchEventImpl(Window.java:2489)
      at java.awt.Component.dispatchEvent(Component.java:4488)
      at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:668)
      at java.awt.EventQueue.access$400(EventQueue.java:81)
      at java.awt.EventQueue$2.run(EventQueue.java:627)
      at java.awt.EventQueue$2.run(EventQueue.java:625)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
      at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
      at java.awt.EventQueue$3.run(EventQueue.java:641)
      at java.awt.EventQueue$3.run(EventQueue.java:639)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:638)
      at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
      at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
  </code></pre>
  
  <p>How can I solve this? I have checked the location of the image, and have tried from different locations and always get the same error!</p>
  
  <p>I'm using the Netbeans IDE.</p>