Override valueof and toString in Java enum

Question

The values in my enum are words that need to have spaces in them  but enums can t have spaces in their values so it s all bunched up  I want to override toString   to add these spaces where I tell it to   I also want the enum to provide the correct enum when I use valueOf   on the same string that I added the spaces to   For example   public enum RandomEnum        StartHere       StopHere     Call toString   on RandomEnum whose value is StartHere returns string  Start Here   Call valueof   on that same string   Start Here   returns enum value StartHere   How can I do this

User · Answer

You can use a static Map in your enum that maps Strings to enum constants. Use it in a 'getEnum' static method. This skips the need to iterate through the enums each time you want to get one from its String value.

public enum RandomEnum {

    StartHere("Start Here"),
    StopHere("Stop Here");

    private final String strVal;
    private RandomEnum(String strVal) {
        this.strVal = strVal;
    }

    public static RandomEnum getEnum(String strVal) {
        if(!strValMap.containsKey(strVal)) {
            throw new IllegalArgumentException("Unknown String Value: " + strVal);
        }
        return strValMap.get(strVal);
    }

    private static final Map<String, RandomEnum> strValMap;
    static {
        final Map<String, RandomEnum> tmpMap = Maps.newHashMap();
        for(final RandomEnum en : RandomEnum.values()) {
            tmpMap.put(en.strVal, en);
        }
        strValMap = ImmutableMap.copyOf(tmpMap);
    }

    @Override
    public String toString() {
        return strVal;
    }
}

Just make sure the static initialization of the map occurs below the declaration of the enum constants.

BTW - that 'ImmutableMap' type is from the Google guava API, and I definitely recommend it in cases like this.

EDIT - Per the comments:

This solution assumes that each assigned string value is unique and non-null. Given that the creator of the enum can control this, and that the string corresponds to the unique & non-null enum value, this seems like a safe restriction.
I added the 'toSTring()' method as asked for in the question

User · Answer

The following is a nice generic alternative to valueOf    public static RandomEnum getEnum String value      for  RandomEnum re   RandomEnum values          if  re description compareTo value     0          return re              throw new IllegalArgumentException  Invalid RandomEnum value      value

User · Answer

Try this  but i don t sure that will work every where     public enum MyEnum       A  Start There        B  Start Here         MyEnum String name            try               Field fieldName   getClass   getSuperclass   getDeclaredField  name                fieldName setAccessible true               fieldName set this  name               fieldName setAccessible false             catch  Exception e

User · Answer

You can try out this code  Since you cannot override valueOf method you have to define a custom method  getEnum in the sample code below  which returns the value that you need and change your client to use this method instead   public enum RandomEnum        StartHere  Start Here        StopHere  Stop Here         private String value       RandomEnum String value            this value   value             public String getValue             return value              Override     public String toString             return this getValue               public static RandomEnum getEnum String value            for RandomEnum v   values                if v getValue   equalsIgnoreCase value   return v          throw new IllegalArgumentException

User · Answer

You still have an option to implement in your enum this    public static  lt T extends Enum lt T gt  gt  T valueOf Class lt T gt  enumType  String name

User · Answer

How about a Java 8 implementation   null can be replaced by your default Enum  public static RandomEnum getEnum String value        return Arrays stream RandomEnum values    filter m - gt  m value equals value   findAny   orElse null      Or you could use     findAny   orElseThrow NotFoundException  new

User · Answer

I don t think your going to get valueOf  Start Here   to work  But as far as spaces   try the following     static private enum RandomEnum       R  Start There         G  Start Here         String value      RandomEnum String s            value   s           System out println RandomEnum G value   System out println RandomEnum valueOf  G   value    Start Here Start Here

[java] Override valueof() and toString() in Java enum

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