什么是最好的方法来使用存储在Enum字符串字面量的值? 例如:

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

然后我就可以用《风尚》了。将其字符串表示形式返回为Mode1。而不必一直调用Mode.mode1.toString()。


当前回答

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

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

你可以像下面这样调用任何你想从枚举中获取字符串值的地方。

Modes.MODE1.getvalue();

这将返回“Mode1”作为字符串。

其他回答

我的解决方案!

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!");

    }
}

你不能。我认为你有四个选择。这四家公司都提供了解决方案,但方法略有不同。

选项一:在枚举上使用内置name()。如果您不需要任何特殊的命名格式,这是非常好的。

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

选项二:如果你想要更多的控制,给你的枚举添加覆盖属性

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:使用静态韵母代替枚举:

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public、static和final:

public interface Modes {

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

每个枚举都有一个name()和valueOf(String)方法。前者返回enum的字符串名称,后者给出名称为该字符串的enum值。这就是你要找的吗?

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

Enum本身也有一个静态valueOf(Class, String),所以你也可以使用:

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

此方法适用于任何枚举:

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();
    }
}

Enum是一个有点特殊的类。枚举可以存储额外的字段,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;
    }
}

现在你可以说:

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

并查看输出: 一个