title: Images display in swing with loading and unloading it from memory
body: <p>I have to read 10000 or more images from a folder and display it in a <code>Jpanel</code>.
  At a time user can view 5 rows in the screen. When user scroll down I should load the other 5 rows in to the screen. </p>
  
  <p>When user scroll down I want to unload those previous loaded images from memory and load it again when user scroll up.</p>
  
  <p>How can I achieve this?</p>
  
  <p>What is the best way to load image in to panel with high performance. </p>
  
  <p>Without scrolling what could be the alternative way to display large number(more than 10000) images to <code>Jpanel</code>.</p>