枚举类的简单应用

java 枚举类简单定义与应用

1. 什么是枚举类：（举个栗子????）

   // 声明枚举时必须使用 enum 关键字
   public enum ResTypeEnum implements ResTypeImpl {
   
   /**
   * 艺术品
   */
   YP(1, "艺术品", "ADBA_RES_AW", "aw"),
   YT(2, "艺术品图片", "ADBA_RES_AWIMG", "awimg"),
   RW(3, "艺术人物", "ADBA_RES_GA", "ga"),
   TJ(4, "图书集", "ADBA_RES_SET", "book-set"),
   TS(5, "图书", "ADBA_RES_BOOK", "book"),
   KA(6, "刊", "ADBA_RES_JOURNAL", "journal"),
   QK(7, "期", "ADBA_RES_PERIODICAL", "periodical"),
   PJ(8, "拍卖机构", "ADBA_RES_AC", "ac"),
   CJ(9, "出版机构", "ADBA_RES_EC", "ec"),
   HJ(10, "画廊机构", "ADBA_RES_GC", "gc"),
   WJ(11, "文博机构", "ADBA_RES_CEC", "cec"),
   QJ(12, "其他机构", "ADBA_RES_ORG", "org"),
   PM(13, "拍卖会", "ADBA_RES_AUCTION", "auction"),
   PZ(14, "拍卖专场", "ADBA_RES_ASA", "asa"),
   ZL(15, "展览会", "ADBA_RES_EXHIBITION", "exhibition"),
   QT(16, "其他活动", "ADBA_RES_ACTIVITY", "activity"),
   WX(17, "文献", "ADBA_RES_INFO", "info"),
   SP(18, "视频", "ADBA_RES_VIDEO", "video"),
   ZP(19, "非艺术品图片", "ADBA_RES_IMG", "img");
   
   
   private Long resId;
   private String name;
   private String tableName;
   private String abbreviation;
   
   ResTypeEnum(long resId, String name, String tableName, String abbreviation) {
    this.resId = resId;
    this.name = name;
    this.tableName = tableName;
    this.abbreviation = abbreviation;
   }
   
   
   @Override
   public Long getResId() {
    return resId;
   }
   
   
   @Override
   public String getName() {
    return name;
   }
   
   @Override
   public String getTableName() {
    return tableName;
   }
   
   @Override
   public String getAbbreviation() {
    return abbreviation;
   }
   

`
可以看出，枚举类相对普通类只是定义类的关键字由原来的的class ，变为enum。而且多了一段枚举值。

2. 枚举类是使用 与其他class类一样，可以直接调用

  public static void main(String[] args) {
        ResTypeEnum cj = ResTypeEnum.CJ;
        ResTypeEnum.getResIdByTableName("ADS");
    }

3. 定义枚举中常用的方法（根据key获取 value、根据value获取key）

		  /**
     *  根据枚举的value 获取枚举的key
     * @param tableName 枚举的value
     * @return  返回枚举的 code 失败返回 null
     */
    public static Long getResIdByTableName(String tableName){
        ResTypeEnum [] resTypeEnums = values(); //获取枚举的是所有值存入数组
        for (ResTypeEnum resTypeEnum : resTypeEnums) {
            if (resTypeEnum.tableName.equals(tableName.toUpperCase(Locale.ROOT))){
                return resTypeEnum.resId;
            }
        }
        return null;
    }

    /**
     *  根据枚举的code 获取枚举的value
     * @param resId 枚举的code
     * @return 返回枚举的value  失败返回 null
     */
    public static String getTableNameByResId(Long resId){
        ResTypeEnum [] resTypeEnums = values();//获取枚举的是所有值存入数组
        for (ResTypeEnum resTypeEnum : resTypeEnums) {
            if (resTypeEnum.resId.equals(resId)){
                return resTypeEnum.tableName;
            }
        }
        return null;
    }