java 枚举初始化

public enum TestEnum {
    A(0), B(1);
    private Integer i;

    TestEnum(Integer i) {
        System.out.println(i);
        this.i = i;
    }

    static {
        System.out.println("init");
    }

    public static void main(String[] args) {
        System.out.println(TestEnum.A);
    }

}
/*
=== 输出
0
1
init
A
*/