title: What is the most efficient way to check if item exists in Arraylist?
body: <p>What is the most efficient way to do this ? </p>
  
  <p>I have a  ArrayList list called windowList. </p>
  
  <p>GameWindow is bean having startTime and endTime.</p>
  
  <p>For each object i recieve, I need to check the window of the object belongs to any of this windowList values. I need to do it for millions of values.</p>
  
  <p>Please help me with most effeftive way to do this ....</p>