java 自定義可繼承枚舉Enum的案例
public class AbstractEnum { private static final Map<String, AbstractEnum> nameEnumMap = new ConcurrentHashMap<>(); @Getter protected String name; protected AbstractEnum () { } protected AbstractEnum(String name) { this.name = name; if (!nameEnumMap.containsKey(name)) { nameEnumMap.put(name, this); } } public boolean equals(AbstractEnum abstractEnum) { return this.name == null || abstractEnum == null ? false : this.name.equals(abstractEnum.getName()); } public String toString() { return this.name; } public static AbstractEnum valueOf(String name) { if (name == null) throw new NullPointerException('Name is null'); AbstractEnum result = nameEnumMap.get(name); if (result != null) { return result; } throw new IllegalArgumentException( 'No enum constant exists, name is.' + name); } public static void init() { } }二、實際繼承enum,與enum使用方法一致
public class TypeEnum extends AbstractEnum { private static final Map<String, TypeEnum> nameEnumMap = new ConcurrentHashMap<>(); protected TypeEnum(String name) { super(name); if (!nameEnumMap.containsKey(name)) { nameEnumMap.put(name, this); } } public static TypeEnum valueOf(String name) { if (name == null) throw new NullPointerException('Name is null'); TypeEnum result = nameEnumMap.get(name); if (result != null) { return result; } throw new IllegalArgumentException( 'No enum constant exists, name is.' + name); } public static final TypeEnum TYPE_ONE = new TypeEnum('TYPE_ONE');}三、可繼續繼承枚舉,進行枚舉分類。
補充:Java中自定義枚舉(Enum)項的值,可設置為指定的值
一、代碼package base.lang;/** * ClassName: StateEnum * @Description: TODO * @author fuming * @date 2016年11月27日 */public enum StateEnum{//添加枚舉的指定常量online(10),offline(20);//必須增加一個構造函數,變量,得到該變量的值private int mState=0;private StateEnum(int value){mState=value;}/*** @return 枚舉變量實際返回值*/ public int getState() { return mState; } }二、示例
//enum StateEnum orderState=StateEnum.offline; //orderState=StateEnum.online; System.out.println('state='+ orderState.getState()); 三、打印結果
state=20 //測試正常
以上為個人經驗,希望能給大家一個參考,也希望大家多多支持好吧啦網。如有錯誤或未考慮完全的地方,望不吝賜教。
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