如何使用泛型将这两种方法合而为一？

Question

I know a lot of Java Generics questions like this already exist such as ( How to refactor two Java methods into one? ), but I guess I just need to see it with my own, simpler function -- with an example of how to call it, to completely understand java generics...I apologize and thank you in advance!

All I know Is that I will probably need to use instanceof, and Class.forName to handle the different return types (and possibly add a second argument for the desiredClass, or can this be deduced somehow without adding the second argument?)

public static <T> T getSanitizedURI(String theUrl, Class desiredReturnType) {
}

but then what?

public static URI getSanitizedURI(String theUrl) {
        URI sanitizedUri = null;
        try{
            URL url = new URL(theUrl);
            sanitizedUri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
        } catch(Exception e) {
            e.printStackTrace();
        }
        return sanitizedUri;
    }

    public static String getSanitizedURIString(String theUrl) {
        String sanitizedUrl = theUrl;
        try{
            URL url = new URL(theUrl);
            URI uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
            sanitizedUrl = uri.toASCIIString();
        } catch(Exception e) {
            e.printStackTrace();
        }
        return sanitizedUrl;
    }

Answer 1

In my opinion, this is not a good use case for generics. If the user wants a String they can use the method that returns a String . If they want a URI they can use the method that returns a URI . Generics would be more appropriate if it is not possible to determine at the time of writing the method all the different types that the method could be used for, or if the method is to be used for lots of different types.

However, you can reduce the code duplication as follows

public static String getSanitizedURIString(String theUrl) {
    return getSanitizedURI(theUrl).toASCIIString();
}

Note that this will throw a NullPointerException if getSanitizedURI returns null . You may prefer to handle this case differently, such as returning theUrl as suggested by @ViacheslavVedenin.