java. The output is -- B B A -- B C. Can you explain me the code following?

public class ForSwitch {

final static short x = 2;

final static int y = 3;

public static void main(String [] args) {

for (int z = 0; z < 4; z++) {

switch (z) {

case x:

System.out.print("A ");

default:

System.out.print("-- ");

case x - 1:

System.out.print("B ");

break;

case y:

System.out.print("C ");

}

}

}

}