在Java中，如何在枚举本身内获取枚举的值？

I want to override toString() for my enum, Color. However, I can't figure out how to get the value of an instance of Color inside the Color enum. Is there a way to do this in Java?

我想为我的枚举，颜色覆盖toString（）。但是，我无法弄清楚如何在Color枚举中获取Color实例的值。有没有办法在Java中这样做？

Example:

例：

public enum Color {
    RED,
    GREEN,
    BLUE,
    ...

    public String toString() {
        // return "R" for RED, "G", for GREEN, etc.
    }
}

6 个解决方案

#1

public enum Color {
    RED("R"),
    GREEN("G"),
    BLUE("B");

    private final String str;
    private Color(String s){
        str = s;
    }
    public String toString() {
        return str;
    }
}

You can use constructors for Enums. I haven't tested the syntax, but this is the idea.

您可以为Enums使用构造函数。我没有测试过语法，但这是个主意。

#2

You can also switch on the type of this, for example:

您也可以打开它的类型，例如：

public enum Foo { 
  A, B, C, D 
  ; 
  @Override 
  public String toString() { 
    switch (this) { 
      case A: return "AYE"; 
      case B: return "BEE"; 
      case C: return "SEE"; 
      case D: return "DEE"; 
      default: throw new IllegalStateException(); 
    } 
  } 
}

#3

Enum.name() - who'd of thunk it?

Enum.name（） - 谁是thunk？

However, in most cases it makes more sense to keep any extra information in an instance variable that is set int the constructor.

但是，在大多数情况下，将任何额外信息保存在构造函数中设置的实例变量中更有意义。

#4

Use super and String.substring():

使用super和String.substring（）：

public enum Color
{
    RED,
    GREEN,
    BLUE;

    public String toString()
    {
        return "The color is " + super.toString().substring(0, 1);
    }
}

#5

Java does this for you by default, it returns the .name() in .toString(), you only need to override toString() if you want something DIFFERENT from the name. The interesting methods are .name() and .ordinal() and .valueOf().

Java默认为你执行此操作，它返回.toString（）中的.name（），如果你想从名称中获得不同的东西，你只需要覆盖toString（）。有趣的方法是.name（）和.ordinal（）和.valueOf（）。

To do what you want you would do

做你想做的事你会做

.toString(this.name().substring(1));

What you might want to do instead is add an attribute called abbreviation and add it to the constructor, add a getAbbreviation() and use that instead of .toString()

您可能想要做的是添加一个名为abbreviation的属性并将其添加到构造函数中，添加一个getAbbreviation（）并使用它来代替.toString（）

#6

I've found something like this (not tested tho):

我发现了这样的东西（未经过测试）：

public enum Color {
RED{
public String toString() {
    return "this is red";
}
},
GREEN{
public String toString() {
    return "this is green";
}
},
...

}

Hope it helps a bit !

希望它有点帮助！

#1

public enum Color {
    RED("R"),
    GREEN("G"),
    BLUE("B");

    private final String str;
    private Color(String s){
        str = s;
    }
    public String toString() {
        return str;
    }
}