title: Java: Detect duplicates in ArrayList?
body: <p>How could I go about detecting (returning true/false) whether an ArrayList contains more than one of the same element in Java?</p>
  
  <p>Many thanks,
  Terry</p>
  
  <p><strong>Edit</strong>
  Forgot to mention that I am not looking to compare "Blocks" with each other but their integer values. Each "block" has an int and this is what makes them different.
  I find the int of a particular Block by calling a method named "getNum" (e.g. table1[0][2].getNum();</p>