Java: instantiating an enum using reflection

Question

Suppose you have a text file like:

my_setting = ON some_method = METHOD_A verbosity = DEBUG ... 

That you wish to to update a corresponding object accordingly:

Setting my_setting = ON; Method some_method = METHOD_A; Verbosity verbosity = DEBUG; ... 

Where all are different kind of enums.

I would like to have a generic way to instantiate the enum values. That is, at runtime using reflection, and without knowing the enum types of the object in advance.

I would have imagined something like this:

for (ConfigLine line : lines) {    String[] tokens = line.string.split("=", 2);    String name = tokens[0].trim();    String value = tokens[1].trim();     try    {       Field field = this.getClass().getDeclaredField(name);          if(field.getType().isEnum())       {          // doesn't work (cannot convert String to enum)          field.set(this, value);          // invalid code (some strange generics issue)          field.set(this, Enum.valueOf(field.getType().getClass(), value));       }       else       { /*...*/ }    }    catch //... } 

The question is: what should there be instead? Is it even possible to instantiate an unknown enum given its String representation?

Answer 1

field.set(this, Enum.valueOf((Class<Enum>) field.getType(), value)); 

• getClass() after getType() should not be called - it returns the class of a Class instance
• You can cast Class<Enum>, to avoid generic problems, because you already know that the Class is an enum

Answer 2

Alternative solution with no casting

try {     Method valueOf = field.getType().getMethod("valueOf", String.class);     Object value = valueOf.invoke(null, param);     field.set(test, value); } catch ( ReflectiveOperationException e) {     // handle error here }