자바 enum

public enum Level {

GOLD(3, null), SILVER(2, GOLD), BASIC(1, SILVER);

 

private final int value;

private final Level next;

Level(int value, Level next) {

this.value = value;

this.next = next;

}

public int intValue() {

return value;

}

public Level nextLevel() {

return this.next;

}

public static Level valueOf(int value) {

switch (value) {

case 1:

return BASIC;

case 2:

return SILVER;

case 3:

return GOLD;

default:

throw new AssertionError("Unknown value : " + value);

}

}

}