一、定义enum抽象类
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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、实际继承enum，与enum使用方法一致
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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、可继续继承枚举，进行枚举分类。
补充：Java中自定义枚举（Enum）项的值,可设置为指定的值
一、代码
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package base.lang; /** * ClassName: StateEnum * @Description: TODO * @author fuming * @date 2016年11月27日 */ public enum StateEnum { //添加枚举的指定常量 online( 10 ), offline( 20 ); //必须增加一个构造函数,变量,得到该变量的值 private int mState= 0 ; private StateEnum( int value) { mState=value; } /** * @return 枚举变量实际返回值 */ public int getState() { return mState; } } |
二、示例
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//enum StateEnum orderState=StateEnum.offline; //orderState=StateEnum.online; System.out.println( "state=" + orderState.getState()); |
三、打印结果
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state= 20 //测试正常 |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。
原文链接：https://blog.csdn.net/jiangxuexuanshuang/article/details/87911048
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