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使用枚举值作为字符串文字

发布于 2024-11-19 10:38:09 字数 260 浏览 7 评论 0原文

使用枚举中存储的值作为字符串文字的最佳方法是什么？ 例如：

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3
}

然后我可以使用 Mode.mode1 将其字符串表示形式返回为 mode1。无需不断调用 Mode.mode1.toString()。

原文

What is the best way to use the values stored in an Enum as String literals?
For example:

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3
}

Then later I could use Mode.mode1 to return its string representation as mode1. Without having to keep calling Mode.mode1.toString().

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评论（19）

猥琐帝 2024-11-26 10:38:10

此方法应该适用于任何enum：

public enum MyEnum {
    VALUE1,
    VALUE2,
    VALUE3;

    public int getValue() {
        return this.ordinal();
    }

    public static DataType forValue(int value) {
        return values()[value];
    }

    public String toString() {
        return forValue(getValue()).name();
    }
}

This method should work with any enum:

public enum MyEnum {
    VALUE1,
    VALUE2,
    VALUE3;

    public int getValue() {
        return this.ordinal();
    }

    public static DataType forValue(int value) {
        return values()[value];
    }

    public String toString() {
        return forValue(getValue()).name();
    }
}
回复 原文
影子的影子 2024-11-26 10:38:10

我发现这个更容易防止类型错误：

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3;

    String str;

    Modes(){
        this.str = super.name();
    }

    @Override
    @NonNull
    public String toString() {
        return str;
    }

但是 - 当您需要在 log/println 上使用 String 或每当 java 自动编译 toString() 方法时，这可能会起作用，但在像这样的代码行上 ->

// sample method that require (string,value)
intent.putExtra(Modes.mode1 ,shareElement.getMode()); // java error
// first argument enum does not return value

相反，如上所述，在这种情况下，您仍然需要扩展枚举并使用 .name() ：

intent.putExtra(Modes.mode1.name() ,shareElement.getMode());

i found this one is more easy for preventing type error:

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3;

    String str;

    Modes(){
        this.str = super.name();
    }

    @Override
    @NonNull
    public String toString() {
        return str;
    }

however - this may work when you need to use a String on a log/println or whenever java compiles the toString() method automatically, but on a code line like this ->

// sample method that require (string,value)
intent.putExtra(Modes.mode1 ,shareElement.getMode()); // java error
// first argument enum does not return value

instead as mentioned above you will still have to extend the enum and use .name() in those cases like this:

intent.putExtra(Modes.mode1.name() ,shareElement.getMode());
回复 原文
彩扇题诗 2024-11-26 10:38:10

使用 mode1.name() 或 String.valueOf(Modes.mode1)

use mode1.name() or String.valueOf(Modes.mode1)

回复 原文
黯然 2024-11-26 10:38:10

经过多次尝试我得到了这个解决方案

public static enum Operation {

    Addition, Subtraction, Multiplication, Division,;

    public String getUserFriendlyString() {
        if (this==Addition) {
            return " + ";
        } else if (this==Subtraction) {
            return " - ";
        } else if (this==Multiplication) {
            return " * ";
        } else if (this==Division) {
            return " / ";
        }
        return "undefined";
       }
}

after many tries I have come with this solution

public static enum Operation {

    Addition, Subtraction, Multiplication, Division,;

    public String getUserFriendlyString() {
        if (this==Addition) {
            return " + ";
        } else if (this==Subtraction) {
            return " - ";
        } else if (this==Multiplication) {
            return " * ";
        } else if (this==Division) {
            return " / ";
        }
        return "undefined";
       }
}
回复 原文
傲影 2024-11-26 10:38:10

你可以试试这个：

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3;

    public String toString(){
        switch(this) {
            case some-really-long-string:
                return "some-really-long-string";
            case mode2:
                return "mode2";
            default: return "undefined";
        }
    }
}

You can try this:

public enum Modes {
    some-really-long-string,
    mode1,
    mode2,
    mode3;

    public String toString(){
        switch(this) {
            case some-really-long-string:
                return "some-really-long-string";
            case mode2:
                return "mode2";
            default: return "undefined";
        }
    }
}
回复 原文
难忘№最初的完美 2024-11-26 10:38:09

你不能。我想你这里有四个选择。所有四个都提供了一个解决方案，但方法略有不同...

选项一：在枚举上使用内置的name()。如果您不需要任何特殊的命名格式，这完全没问题。

    String name = Modes.mode1.name(); // Returns the name of this enum constant, exactly as declared in its enum declaration.

选项二： 如果您想要更多控制，请向枚举添加覆盖属性

public enum Modes {
    mode1 ("Fancy Mode 1"),
    mode2 ("Fancy Mode 2"),
    mode3 ("Fancy Mode 3");

    private final String name;       

    private Modes(String s) {
        name = s;
    }

    public boolean equalsName(String otherName) {
        // (otherName == null) check is not needed because name.equals(null) returns false 
        return name.equals(otherName);
    }

    public String toString() {
       return this.name;
    }
}

选项三： 使用静态final代替枚举：

public final class Modes {

    public static final String MODE_1 = "Fancy Mode 1";
    public static final String MODE_2 = "Fancy Mode 2";
    public static final String MODE_3 = "Fancy Mode 3";

    private Modes() { }
}

选项四： 接口的每个字段都是公共的、静态的和final的：

public interface Modes {

    String MODE_1 = "Fancy Mode 1";
    String MODE_2 = "Fancy Mode 2";
    String MODE_3 = "Fancy Mode 3";  
}

You can't. I think you have FOUR options here. All four offer a solution but with a slightly different approach...

Option One: use the built-in name() on an enum. This is perfectly fine if you don't need any special naming format.

    String name = Modes.mode1.name(); // Returns the name of this enum constant, exactly as declared in its enum declaration.

Option Two: add overriding properties to your enums if you want more control

public enum Modes {
    mode1 ("Fancy Mode 1"),
    mode2 ("Fancy Mode 2"),
    mode3 ("Fancy Mode 3");

    private final String name;       

    private Modes(String s) {
        name = s;
    }

    public boolean equalsName(String otherName) {
        // (otherName == null) check is not needed because name.equals(null) returns false 
        return name.equals(otherName);
    }

    public String toString() {
       return this.name;
    }
}

Option Three: use static finals instead of enums:

public final class Modes {

    public static final String MODE_1 = "Fancy Mode 1";
    public static final String MODE_2 = "Fancy Mode 2";
    public static final String MODE_3 = "Fancy Mode 3";

    private Modes() { }
}

Option Four: interfaces have every field public, static and final:

public interface Modes {

    String MODE_1 = "Fancy Mode 1";
    String MODE_2 = "Fancy Mode 2";
    String MODE_3 = "Fancy Mode 3";  
}
回复 原文
dawn曙光 2024-11-26 10:38:09

每个枚举都有一个 name() 和一个 valueOf(String) 方法。前者返回枚举的字符串名称，后者给出名称为字符串的枚举值。这就是您要找的吗？

String name = Modes.mode1.name();
Modes mode = Modes.valueOf(name);

Enum 本身还有一个静态 valueOf(Class, String) ，因此您也可以使用：

Modes mode = Enum.valueOf(Modes.class, name);

Every enum has both a name() and a valueOf(String) method. The former returns the string name of the enum, and the latter gives the enum value whose name is the string. Is this like what you're looking for?

String name = Modes.mode1.name();
Modes mode = Modes.valueOf(name);

There's also a static valueOf(Class, String) on Enum itself, so you could also use:

Modes mode = Enum.valueOf(Modes.class, name);
回复 原文
错々过的事 2024-11-26 10:38:09

您可以为每个枚举值重写 toString() 方法。

示例：

public enum Country {

  DE {
    @Override
    public String toString() {
      return "Germany";
    }
  },
  IT {
    @Override
    public String toString() {
      return "Italy";
    }
  },
  US {
    @Override
    public String toString() {
      return "United States";
    }
  }

}

用法：

public static void main(String[] args) {
  System.out.println(Country.DE); // Germany
  System.out.println(Country.IT); // Italy
  System.out.println(Country.US); // United States
}

You could override the toString() method for each enum value.

Example:

public enum Country {

  DE {
    @Override
    public String toString() {
      return "Germany";
    }
  },
  IT {
    @Override
    public String toString() {
      return "Italy";
    }
  },
  US {
    @Override
    public String toString() {
      return "United States";
    }
  }

}

Usage:

public static void main(String[] args) {
  System.out.println(Country.DE); // Germany
  System.out.println(Country.IT); // Italy
  System.out.println(Country.US); // United States
}
回复 原文
ヤ经典坏疍 2024-11-26 10:38:09

正如 Benny Neugebauer 提到的，您可以覆盖 toString()。然而，我更喜欢这样的内容：

public enum Country{
    SPAIN("España"),
    ITALY("Italia"),
    PORTUGAL("Portugal");


    private String value;

    Country(final String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }

    @Override
    public String toString() {
        return this.getValue();
    }
}

您还可以添加一个静态方法来检索所有字段、打印所有字段等， 而不是覆盖每个枚举字段的 toString。
只需调用 getValue 即可获取与每个 Enum 项关联的字符串

As Benny Neugebauer mentions, you could overwrite the toString(). However instead overwriting the toString for each enum field I like more something like this:

public enum Country{
    SPAIN("España"),
    ITALY("Italia"),
    PORTUGAL("Portugal");


    private String value;

    Country(final String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }

    @Override
    public String toString() {
        return this.getValue();
    }
}

You could also add a static method to retrieve all the fields, to print them all, etc.
Simply call getValue to obtain the string associated to each Enum item

回复 原文
盛装女皇 2024-11-26 10:38:09

mode1.name() 或 String.valueOf(mode1)。恐怕没有比这更好的了

mode1.name() or String.valueOf(mode1). It doesn't get better than that, I'm afraid

回复 原文
听不够的曲调 2024-11-26 10:38:09
public enum Modes {
  MODE1("Mode1"),
  MODE2("Mode2"),
  MODE3("Mode3");

 private String value;
 public String getValue() {
    return value;
   }
 private Modes(String value) {
  this.value = value;
 } 
}

您可以在任何想要从枚举中获取字符串形式的值的地方进行如下调用。

Modes.MODE1.getvalue();

这将以字符串形式返回“Mode1”。

public enum Modes {
  MODE1("Mode1"),
  MODE2("Mode2"),
  MODE3("Mode3");

 private String value;
 public String getValue() {
    return value;
   }
 private Modes(String value) {
  this.value = value;
 } 
}

you can make a call like below wherever you want to get the value as a string from the enum.

Modes.MODE1.getvalue();

This will return "Mode1" as a String.

回复 原文
梦幻的心爱 2024-11-26 10:38:09

对于我的枚举，我真的不喜欢为它们每个分配 1 个字符串。这就是我在枚举上实现 toString() 方法的方法。

enum Animal
{
    DOG, CAT, BIRD;
    public String toString(){
        switch (this) {
            case DOG: return "Dog";
            case CAT: return "Cat";
            case BIRD: return "Bird";
        }
        return null;
    }
}

For my enums I don't really like to think of them being allocated with 1 String each. This is how I implement a toString() method on enums.

enum Animal
{
    DOG, CAT, BIRD;
    public String toString(){
        switch (this) {
            case DOG: return "Dog";
            case CAT: return "Cat";
            case BIRD: return "Bird";
        }
        return null;
    }
}
回复 原文
余生一个溪 2024-11-26 10:38:09

据我所知，获得该名称的唯一方法是

Mode.mode1.name();

如果您确实需要这种方式，但是，您可以这样做：

public enum Modes {
    mode1 ("Mode1"),
    mode2 ("Mode2"),
    mode3 ("Mode3");

    private String name;       

    private Modes(String s) {
        name = s;
    }
}

As far as I know, the only way to get the name would be

Mode.mode1.name();

If you really need it this way, however, you could do:

public enum Modes {
    mode1 ("Mode1"),
    mode2 ("Mode2"),
    mode3 ("Mode3");

    private String name;       

    private Modes(String s) {
        name = s;
    }
}
回复 原文
深海少女心 2024-11-26 10:38:09

您可以使用Mode.mode1.name()，但通常不需要这样做。

Mode mode =
System.out.println("The mode is "+mode);

You can use Mode.mode1.name() however you often don't need to do this.

Mode mode =
System.out.println("The mode is "+mode);
回复 原文
长梦不多时 2024-11-26 10:38:09

我的解决方案解决你的问题！

import java.util.HashMap;
import java.util.Map;

public enum MapEnumSample {
    Mustang("One of the fastest cars in the world!"), 
    Mercedes("One of the most beautiful cars in the world!"), 
    Ferrari("Ferrari or Mercedes, which one is the best?");

    private final String description;
    private static Map<String, String> enumMap;

    private MapEnumSample(String description) {
        this.description = description;
    }

    public String getEnumValue() {
        return description;
    }

    public static String getEnumKey(String name) {
        if (enumMap == null) {
            initializeMap();
        }
        return enumMap.get(name);
    }

    private static Map<String, String> initializeMap() {
        enumMap = new HashMap<String, String>();
        for (MapEnumSample access : MapEnumSample.values()) {
            enumMap.put(access.getEnumValue(), access.toString());
        }
        return enumMap;
    }

    public static void main(String[] args) {

        // getting value from Description
        System.out.println(MapEnumSample.getEnumKey("One of the fastest cars in the world!"));

        // getting value from Constant
        System.out.println(MapEnumSample.Mustang.getEnumValue());

        System.out.println(MapEnumSample.getEnumKey("One of the most beautiful cars in the world!"));
        System.out.println(MapEnumSample.Mercedes.getEnumValue());

        // doesnt exist in Enum
        System.out.println("Mustang or Mercedes, which one is the best?");
        System.out.println(MapEnumSample.getEnumKey("Mustang or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
                + MapEnumSample.getEnumKey("Ferrari or Mustang, which one is the best?") + " is the best!.");

        // exists in Enum
        System.out.println("Ferrari or Mercedes, wich one is the best?");
        System.out.println(MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
                + MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") + " is the best!");

    }
}

my solution for your problem!

import java.util.HashMap;
import java.util.Map;

public enum MapEnumSample {
    Mustang("One of the fastest cars in the world!"), 
    Mercedes("One of the most beautiful cars in the world!"), 
    Ferrari("Ferrari or Mercedes, which one is the best?");

    private final String description;
    private static Map<String, String> enumMap;

    private MapEnumSample(String description) {
        this.description = description;
    }

    public String getEnumValue() {
        return description;
    }

    public static String getEnumKey(String name) {
        if (enumMap == null) {
            initializeMap();
        }
        return enumMap.get(name);
    }

    private static Map<String, String> initializeMap() {
        enumMap = new HashMap<String, String>();
        for (MapEnumSample access : MapEnumSample.values()) {
            enumMap.put(access.getEnumValue(), access.toString());
        }
        return enumMap;
    }

    public static void main(String[] args) {

        // getting value from Description
        System.out.println(MapEnumSample.getEnumKey("One of the fastest cars in the world!"));

        // getting value from Constant
        System.out.println(MapEnumSample.Mustang.getEnumValue());

        System.out.println(MapEnumSample.getEnumKey("One of the most beautiful cars in the world!"));
        System.out.println(MapEnumSample.Mercedes.getEnumValue());

        // doesnt exist in Enum
        System.out.println("Mustang or Mercedes, which one is the best?");
        System.out.println(MapEnumSample.getEnumKey("Mustang or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
                + MapEnumSample.getEnumKey("Ferrari or Mustang, which one is the best?") + " is the best!.");

        // exists in Enum
        System.out.println("Ferrari or Mercedes, wich one is the best?");
        System.out.println(MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") == null ? "I don't know!" : "I believe that "
                + MapEnumSample.getEnumKey("Ferrari or Mercedes, which one is the best?") + " is the best!");

    }
}
回复 原文
天暗了我发光 2024-11-26 10:38:09

您可以简单地使用：

""+ Modes.mode1

You can simply use:

""+ Modes.mode1
回复 原文
柠檬 2024-11-26 10:38:09
public enum Environment
{
    PROD("https://prod.domain.com:1088/"),
    SIT("https://sit.domain.com:2019/"),
    CIT("https://cit.domain.com:8080/"),
    DEV("https://dev.domain.com:21323/");

    private String url;

    Environment(String envUrl) {
        this.url = envUrl;
    }

    public String getUrl() {
        return url;
    }
}

String prodUrl = Environment.PROD.getUrl();

它将打印：

https://prod.domain.com:1088/

This design for 枚举字符串常量适用于大多数情况下。

public enum Environment
{
    PROD("https://prod.domain.com:1088/"),
    SIT("https://sit.domain.com:2019/"),
    CIT("https://cit.domain.com:8080/"),
    DEV("https://dev.domain.com:21323/");

    private String url;

    Environment(String envUrl) {
        this.url = envUrl;
    }

    public String getUrl() {
        return url;
    }
}

String prodUrl = Environment.PROD.getUrl();

It will print:

https://prod.domain.com:1088/

This design for enum string constants works in most of the cases.

回复 原文
拥抱影子 2024-11-26 10:38:09

枚举只是一个有点特殊的类。枚举可以存储附加字段、实现方法等。例如

public enum Modes {
    mode1('a'),
    mode2('b'),
    mode3('c'),
    ;
    char c;

    private Modes(char c) {
        this.c = c;
    }
    public char character() {
        return c;
    }
}

现在您可以说：

System.out.println(Modes.mode1.character())

并查看输出：
一个

Enum is just a little bit special class. Enums can store additional fields, implement methods etc. For example

public enum Modes {
    mode1('a'),
    mode2('b'),
    mode3('c'),
    ;
    char c;

    private Modes(char c) {
        this.c = c;
    }
    public char character() {
        return c;
    }
}

Now you can say:

System.out.println(Modes.mode1.character())

and see output:
a

回复 原文
爱情眠于流年 2024-11-26 10:38:09
package com.common.test;

public  enum Days {


    monday(1,"Monday"),tuesday(2,"Tuesday"),wednesday(3,"Wednesday"),
    thrusday(4,"Thrusday"),friday(5,"Friday"),saturday(6,"Saturday"),sunday(7,"Sunday");

    private int id;
    private String desc;


    Days(int id,String desc){
        this.id=id;
        this.desc=desc;
    }

    public static String getDay(int id){

        for (Days day : Days.values()) {
            if (day.getId() == id) {
                return day.getDesc();
            }
        }
        return null;
    }

    public int getId() {
        return id;
    }

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

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }



};

package com.common.test;

public  enum Days {


    monday(1,"Monday"),tuesday(2,"Tuesday"),wednesday(3,"Wednesday"),
    thrusday(4,"Thrusday"),friday(5,"Friday"),saturday(6,"Saturday"),sunday(7,"Sunday");

    private int id;
    private String desc;


    Days(int id,String desc){
        this.id=id;
        this.desc=desc;
    }

    public static String getDay(int id){

        for (Days day : Days.values()) {
            if (day.getId() == id) {
                return day.getDesc();
            }
        }
        return null;
    }

    public int getId() {
        return id;
    }

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

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }



};
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