类Enum

int compareTo(E o)

比较此枚举与指定对象的顺序。

String name()

返回此枚举常量的名称，在其枚举声明中对其进行声明。

int ordinal()

返回枚举常量的序数（它在枚举声明中的位置，其中初始常量序数为零）。

String toString()

返回枚举常量的名称，它包含在声明中。

public class Test {
	public static void main(String[] args) throws Exception {
		Direction d1 = Direction.FRONT;
		Direction d2 = Direction.BEHIND;
		Direction d3 = Direction.LEFT;
		Direction d4 = Direction.RIGHT;

		System.out.println(d1.compareTo(d1));// 0
		System.out.println(d1.compareTo(d4));// -3
		System.out.println(d4.compareTo(d1));// 3

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

		System.out.println(d1.name());// FRONT
		System.out.println(d2.name());// BEHIND
		System.out.println(d3.name());// LEFT
		System.out.println(d4.name());// RIGHT

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

		System.out.println(d1.ordinal());// 0
		System.out.println(d2.ordinal());// 1
		System.out.println(d3.ordinal());// 2
		System.out.println(d4.ordinal());// 3

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

		System.out.println(d1.toString());// FRONT
		System.out.println(d2.toString());// BEHIND
		System.out.println(d3.toString());// LEFT
		System.out.println(d4.toString());// RIGHT
	}
}

enum Direction {
	FRONT("前"), BEHIND("后"), LEFT("左"), RIGHT("右");

	String name;

	private Direction(String name) {
		this.name = name;
	}
}