Java优学网枚举方法教程：轻松掌握枚举定义与实战应用

public enum OrderStatus {

PENDING_PAYMENT,
PAID,
SHIPPED,
COMPLETED

}

public class EnumDemo {

public static void main(String[] args) {
    OrderStatus[] statuses = OrderStatus.values();
    for (OrderStatus status : statuses) {
        System.out.println(status);
    }
}

}

public void processOrder(OrderStatus status) {

switch (status) {
    case PENDING_PAYMENT:
        sendPaymentReminder();
        break;
    case PAID:
        prepareShipment();
        break;
    case SHIPPED:
        updateTrackingInfo();
        break;
    case COMPLETED:
        generateInvoice();
        break;
}

}

public enum Planet {

MERCURY(3.303e+23, 2.4397e6),
VENUS(4.869e+24, 6.0518e6),
EARTH(5.976e+24, 6.37814e6);

private final double mass;   // 千克
private final double radius; // 米

Planet(double mass, double radius) {
    this.mass = mass;
    this.radius = radius;
}

public double surfaceGravity() {
    double G = 6.67300E-11;
    return G * mass / (radius * radius);
}

public double surfaceWeight(double otherMass) {
    return otherMass * surfaceGravity();
}

}