Attempt to invoke virtual method 'int java.util.Random.nextInt(int)' on a null object reference code example

Example: Attempt to invoke virtual method 'int java.util.Random.nextInt(int)' on a null object reference

the problem: java.lang.NullPointerException: Attempt to invoke virtual method
'int java.util.Random.nextInt(int)' on a null object reference 
//you might do not code that:
Random rand = new Random();