枚举用法

import java.util.EnumSet;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public enum EnumDemo {

PENDING_TO_VISIT(1, "待开始"),
TO_VISIT(2, "工作中"), 
VISITED(3, "已完成");

private Integer code;

private String name;

/**
 * 存放所有的code和enum的转换.
 */
private static final Map<Integer, EnumDemo> CLINIC_VISIT_STATUS_ENUM_MAP = new ConcurrentHashMap<Integer, EnumDemo>(
		EnumDemo.values().length);

EnumDemo(Integer code, String name) {
	this.code = code;
	this.name = name;
}

static {
	/**
	 * 将所有的实体类放入到map中,提供查询.
	 */
	for (EnumDemo cardType : EnumSet.allOf(EnumDemo.class)) {
		CLINIC_VISIT_STATUS_ENUM_MAP.put(cardType.code, cardType);
	}
	//{1=PENDING_TO_VISIT, 2=TO_VISIT, 3=VISITED}
	//System.out.println(CLINIC_VISIT_STATUS_ENUM_MAP);
   /*    for (EnumDemo EnumDemo : EnumDemo.values()) {//和上面的方式完全等价
    	   CLINIC_VISIT_STATUS_ENUM_MAP.put(EnumDemo.getCode(), EnumDemo);
        }
        //{1=PENDING_TO_VISIT, 2=TO_VISIT, 3=VISITED}
       System.out.println(CLINIC_VISIT_STATUS_ENUM_MAP);*/
}

public Integer getCode() {
	return code;
}

public String getName() {
	return name;
}

// 根据类型获取枚举
public static EnumDemo getByCode(Integer code) {
	return CLINIC_VISIT_STATUS_ENUM_MAP.get(code);
}
	//获取enum集合
public static Map<Integer, String> gainList() {
	Map<Integer, String> map = new LinkedHashMap<>();
	for (EnumDemo c : EnumDemo.values()) {
		map.put(c.getCode(), c.getName());
	}
	return map;
}

public static void main(String[] args) {
	//具体值
	String byCode = EnumDemo.PENDING_TO_VISIT.getByCode(1).getName();//主要为了code获取name
	//获取状态code
	Integer code = EnumDemo.PENDING_TO_VISIT.getCode();
	System.out.println(byCode);//待开始
	System.out.println(CLINIC_VISIT_STATUS_ENUM_MAP);//{1=PENDING_TO_VISIT, 2=TO_VISIT, 3=VISITED}
	System.out.println(code);//1
    Map<Integer, String> gainList = EnumDemo.gainList();
	System.out.println(gainList);//{1=待开始, 2=工作中, 3=已完成}
}

}