JEP 495 Question

[Tagir Valeev]

Hello!

I agree that methods like readInt and readDouble should be added, if we
really want to make Java appealing for beginners who try to write console
applications. It looks to me that sometimes we think too much and avoid
making decisions and taking responsibility if there's no single obviously
good way to solve the problem. Here any decent solution would be good
enough, were it just a shortcut to parseDouble(readln()) or having a
Scanner.nextDouble under the hood. Either way is much better than having no
solution at all. Students will get used to it, and we can easily ignore
nitpickers who would criticize it and insist that the opposite solution
should be implemented. Because nitpickers will do this in any case.

I personally would prefer even more beginner-friendly solution, like
repeatedly asking for a number and displaying a friendly error message if
the user types something different (without throwing an exception). Sure,
this is not flexible and should not be used in production-quality
applications. But this is what would be the least scary for beginners.

I also see the desire to keep the API surface not bloated, but you can see
how many people connected to education actually requested methods to read
numbers in this mailing list. Do you remember them requesting anything
else? To me it's clear that reading numbers in a one method call is a
single most wanted addition to IO. You'll see many more such requests after
the feature is graduated (well, unless every single student moves to
Python).

With best regards,
Tagir Valeev

On Thu, Nov 7, 2024 at 9:47 PM Kenneth Fogel <kfogel at dawsoncollege.qc.ca>
wrote:

> I understand your position and ten years ago I would agree with it
> wholeheartedly but not anymore. I am excited about JEP 445 and how it might
> bring more students and self learners to Java. Today’s learners want fast
> results. It is why I believe so many are hooked on Python. I dislike Python
> because it is an untyped language, but we cannot ignore that:
>
>
>
> Python: loan = input("Loan: ")
>
> makes more sense to those starting out than:
>
> Java: var loan = Double.parseDouble(readln("Loan: "));
>
>
>
> Both will throw exceptions if you enter “bob” for the value, just at
> different points in the execution.
>
>
>
> I feel that any language should evolve not only with new features but in
> new ways to learn that match how people learn today. I do agree that there
> can easily be a flood of requests that could probably make Java look like
> GW-BASIC.
>
>
>
> Thank you, Brian, for providing the summary of why you and the Java team
> decided not to have a numeric read. As they say, we will have to agree to
> disagree.
>
>
>
> Ken
>
>
>
>
>
>
>
>
>
>
>
> *From:* amber-dev <amber-dev-retn at openjdk.org> *On Behalf Of *Brian Goetz
> *Sent:* November 7, 2024 2:41 PM
> *To:* Barry Burd <bburd at drew.edu>; amber-dev at openjdk.org
> *Subject:* Re: JEP 495 Question
>
>
>
> Yes, these were considered, and dismissed with prejudice, in part because
> the model implied by readInt and readDouble is a problematic one, because
> it greatly complicates the "reading state" that has to be understood by the
> user (e.g., what if there's no digits on the line, does it read another
> line?  what if the digits end mid-line, does it leave the cursor there?
> what if it consumes all the characters on the line, and then you read a
> string?)  These are issues that invariably trip up beginners and
> experienced users alike.
>
> The locution you suggest, which is to use readln() to read a line into a
> String, then parseInt() to convert to an int, is more wordy than some of
> the alternatives, but much clearer and simpler as to what is going on,
> because it composes two simple functions (read a string, convert a string
> to an int).  This is good for beginners, because they can see that there
> are steps here to get the data into the form they want.  The readInt()
> method provides the illusion of simplicity, but ends up moving significant
> complexity to where we are more likely to trip over it in the dark.
>
> I'm not saying there will never be a richer way to do this, but readInt()
> and friends are definitely not it.
>
> More generally, one of the worst things about creating an IO class is that
> it immediately becomes  target for a flood of "can you just add my one
> favorite method" requests.  We might add a few more methods to it in the
> next decade.  But we also might not; less is more.
>
> On 11/7/2024 12:06 PM, Barry Burd wrote:
>
> I see that parameterless println() and readln() methods are being added to
> java.io.IO in JEP 495. I'm still wondering if there's been any thought to
> including methods like readInt and readDouble. In the early stage of an
> introduction to Java, it's common to have the student input int values and
> double values for simple examples. With the current spec, the best way to
> do this (as far as I can see) is
>
>       var n = Integer.parseInt(readln("Enter a number"));
>
> It seems natural to simplify this with a readInt method, and the addition
> of such a method wouldn't weigh heavily on the java.io.IO package.
> Any thoughts?
>   --Barry
>
>
>
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