枚举类型与泛型的学习

interface Constants {
    public static final int Constants_A = 1;
    public static final int Constants_B = 12;

}

public class ConstantsTest {
    enum Constants2{
        Constants_A,Constants_B
    }
    public static void doit(int c){
        switch (c){
            case Constants.Constants_A:
                System.out.println("doit() Constants_A");
                break;
            case Constants.Constants_B:
                System.out.println("doit() COnstants_B");
                break;
        }
    }

    public static void doit2(Constants2 c){
        switch (c){
            case Constants_A:
                System.out.println("doit() Constants_A");
                break;
            case Constants_B:
                System.out.println("doit() COnstants_B");
                break;
        }
    }

    public static void compare(Constants2 c){
        for (int i = 0; i