Question

I’m looking for a Java library for converting values that supports generic types. That is, if I have Foo<T>, then the library should support converting a String to Foo<String> or Foo<Int>.

Of course given a class, one cannot tell its generic component. My aim is to populate a bean with string values. So the bean’s properties can be examined for the generic type information.

Answer 1

Here is a skeleton of a solution:

public interface Converter {
    boolean canConvert(Class<?> sourceCls, Type targetType);

    Object convert(Object source, Class<?> sourceClass, Type targetType) throws CannotConvertException;
}

Note the source type is a Class, but the target is a Type. If it is a Class, then code can be delegated to one of the existing libraries. If targetType is a ParameterizedType, then you can get the type arguments (classes) from it, then the standard libraries can be used to convert to them.

To use:

• for fields: Type targetType = field.getGenericType()
• for setter methods: Type targetType = method.getGenericParameterTypes()[0]