Question

I need to code a method, something like :

MyClassObject convert(Class MyClass , String value)

The convert method’s job is to convert the String into an object of MyClass, where MyClass can be anything (except a primitive) – Integer, Boolean, Character, Date… the possibilities are huge here – and that’s the reason I gave up my stupid if-else block to handle all the cases individually.

I could see something related to this for C# (don’t know if it works) , don’t know if we have a Java equivalent for this or this

I understand not everything can be converted from a string, I am ready to handle exceptions for non-parseable items.

I don’t know if this is possible or not. If not, please help me with a proper design pattern for my code.

Thanks !

Answer 1

Your best bet is probably the ServiceLoader mechanism. This allows you to define a pair of interfaces, e.g.:

interface StringConverterProvider{
    StringConverter<T> getConverterFor(Class<T> clazz);
}

interface StringConverter<T>{
    T convert(String s);
}

… and then locate all the implementations of these interfaces available at runtime, like so:

ServiceLoader<StringConverterProvider> converterProviderLoader
    = ServiceLoader.load(StringConverterProvider.class);

T convert(String s, Class<T> t){
    for(StringConverterProvider scProv : converterProviderLoader){
        StringConverter<T> converter = scProv.getConverterFor(t);
        if (converter != null)
            return converter.convert(s);
        }
    return null;
}

You make your implementation of the interfaces available to ServiceLoader by listing them in a special file in the META-INF directory in your jar file; see the javadoc for details.