Difference between the >> and >>> operators

a >> b will shift the number a by b bits to the right in an unsigned manner. It will always add a zero to the left side to fill up the spot that frees up.

a >>> b will shift the number a by b bits to the right in a signed manner. It will add a zero to the left side if a is positive, but add a one if a is negative as to keep it negative.

Right shifting by one will divide the number by two.
Check out the output of following example program to get the hang of it:

public class Main {
   public static void main(String []args) {
      unsignedShift(123);
      unsignedShift(-123);
 
      signedShift(123);
      signedShift(-123); 
   }
 
   public static void unsignedShift(int n) {
      System.out.println("Unsigned right shift of " + n);
      System.out.println("  before: " + Integer.toBinaryString(n));
      System.out.println("  after:  " + Integer.toBinaryString(n >>> 1));
   }
 
   public static void signedShift(int n) {
      System.out.println("Signed right shift of " + n);
      System.out.println("  before: " + Integer.toBinaryString(n));
      System.out.println("  after:  " + Integer.toBinaryString(n >> 1));
   }
} 

outputs: (modified for readability reasons)

Unsigned right shift of 123
  before: 00000000 00000000 00000000 01111011
  after:  00000000 00000000 00000000 00111101  <-- added zero to the front
Unsigned right shift of -123
  before: 11111111 11111111 11111111 10000101
  after:  01111111 11111111 11111111 11000010  <-- added zero to the front making
                                                   the number positive!
Signed right shift of 123
  before: 00000000 00000000 00000000 01111011
  after:  00000000 00000000 00000000 00111101  <-- added zero to the front 
                                                   because 123 is positive
Signed right shift of -123
  before: 11111111 11111111 11111111 10000101
  after:  11111111 11111111 11111111 11000010  <-- added one to the front keeping
                                                   the result negative