Java枚举实战

枚举的应用在项目中比较常见，当一个变量有几种固定可能的取值时，就可以将它定义成一个枚举。下面拿小说种类来定义一个枚举。

假设小说的种类有6种：武侠小说、推理小说、悬疑小说、历史小说、军事小说、言情小说。

public enum NovelEnum {
    MARTIAL(0,"武侠小说"),
    MYSTERY(1,"推理小说"),
    SUSPENSE(2,"悬疑小说"),
    HISTORICAL(3,"历史小说"),
    MILITARY(4,"军事小说"),
    ROMANCE(5,"言情小说");

    private final Integer code;
    private final String type;

    NovelEnum(Integer code,String type){
        this.code = code;
        this.type = type;
    }

    public Integer getCode() {
        return code;
    }

    public String getType() {
        return type;
    }

    public static String getType(Integer code){
        for (NovelEnum novel : NovelEnum.values()){
            if (novel.code == code){
                return novel.type;
            }
        }
        return "";
    }

    public static String getName(Integer code){
        for (NovelEnum novel : NovelEnum.values()){
            if (novel.code == code){
                return novel.name();
            }
        }
        return "";
    }

    public static Integer getCode(String type){
        if (StringUtil.isBlank(type)){
            return null;
        }
        for (NovelEnum novel: NovelEnum.values()){
            if (novel.type.equals(type)){
                return novel.code;
            }
        }
        return null;
    }
    public static List<NovelEnum> getEnumVo(){
        List<NovelEnum> enums = new ArrayList<>();
        for (NovelEnum novel : NovelEnum.values()){
            enums.add(novel);
        }
        return enums;
    }
}

 为了用一下这个枚举，我们再定义一个小说实体类Novel.java

public class Novel {
    private Integer id;
    private String name;
    private Integer typeCode;
    private String typeName;
    private Integer authId;
    private String authName;



    public Novel( String name, String typeName, Integer authId, String authName) {
        this.id = new Random().nextInt(1000);
        this.name = name;
        this.typeCode = NovelEnum.getCode(typeName);
        this.typeName = typeName;
        this.authId = authId;
        this.authName = authName;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getTypeCode() {
        return typeCode;
    }

    public void setTypeCode(Integer typeCode) {
        this.typeCode = typeCode;
    }

    public String getTypeName() {
        return typeName;
    }

    public void setTypeName(String typeName) {
        this.typeName = typeName;
    }

    public Integer getAuthId() {
        return authId;
    }

    public void setAuthId(Integer authId) {
        this.authId = authId;
    }

    public String getAuthName() {
        return authName;
    }

    public void setAuthName(String authName) {
        this.authName = authName;
    }

    @Override
    public String toString() {
        return "Novel{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", typeCode=" + typeCode +
                ", typeName='" + typeName + '\'' +
                ", authId=" + authId +
                ", authName='" + authName + '\'' +
                '}';
    }
}

 

public class NovelEnumTest {
    public static void main(String[] args) {
        Novel novel = new Novel("斗破苍穹",NovelEnum.MARTIAL.getType(),112,"唐家三少");
        Novel novel2 = new Novel("鬼吹灯",NovelEnum.SUSPENSE.getType(),225,"南派三叔");
        System.out.println(novel);
        System.out.println(novel2);
    }
}

 

有几个注意的点

①Enum的属性应该都是不可变的。

②一般情况下Enum的操作方法，比如上文的getName、getType、getCode都是静态方法，这样方便我们在操作中使用，至于你想定义哪些方法随你便。