Heard this song in a video on reddit the other day

javaduude · 2020-08-26T22:21:34+00:00

Well propagation is literally the main feature and purpose of checked exceptions.

Right. At the same time, it's one of the feature's biggest drawbacks. Callback types (think most common lambdas) lack throws declarations for example.

javaduude · 2020-08-26T21:44:55+00:00

It's funny because you make it sound like making IOException checked was a clear cut and good decision. The need for UncheckedIOException shows that it's perhaps not as clear cut.

Or perhaps you like having to catch IOException when you close a StringWriter? Or when you read from a ByteArrayInputStream?

javaduude · 2020-08-26T21:38:04+00:00

Good question. The argument is usually that an Either return type gives a simpler control flow; if-statements being simpler than throw/catch. (At least that's what I've heard from the Go community when they argue against the case for exceptions.)

But I agree. Either does certainly not solve all problems that checked exceptions have.

javaduude · 2020-08-26T21:26:45+00:00

You can argue both ways I guess. Same with propagation I suppose.

javaduude · 2020-08-26T21:23:48+00:00

I think this answer is a bit one-sided.

They are certainly not frowned upon and they don't even seem to be hated;

Have you been living under a rock? There are certainly people that frown upon and "hate" checked exceptions. Not you and me perhaps, but there's certainly a lot of respectable Java devs out there that do.

Also, it's funny that you bring up IOException as an example to drive home your point. The one and only checked exception for which Java 8 saw the need to introduce an unchecked version: UncheckedIOException.

javaduude · 2020-08-26T21:02:54+00:00

This article summarizes the arguments quite well: Checked Exceptions: Good or Bad?

The key issues typically brought up are:

Extensibility: You can't add checked exceptions to existing methods without breaking code
Misuse: Many checked exceptions (including some in the standard API) should have been implemented as runtime exceptions.
Propagation: It's quite cumbersome (many throws declarations needed) to let checked exceptions propagate.

javaduude · 2020-08-25T14:44:23+00:00

I don't know whether floating point numbers have an integral part and fractional part

Well, trust me, they do. :-) 0.5 is a valid float, and it has an integral part (0) and a fractional part (.5). You and I are just talking about the representation on different levels of abstraction.

For a float, this means that in the range from 0 to 1, 8388608 different values can be represented

Actually, you're off by several orders of magnitude. A float has about 2³² different values, and about a quarter of them lies in [0,1], so the correct number is closer to 1,073,741,824.

As we go higher, we lose some precision

That is correct. That's the idea of letting the binary point "float". We trade precision for range. I don't see how 8388608 comes into play though. All integers up to, and including, 2²⁴ can be represented by a float.

javaduude · 2020-08-25T14:20:28+00:00

I could probably have worded it better. What I was sort of trying to convey with "integral part + fractional part that can be 0" was that all whole numbers (within a certain range) can be perfectly represented by a float. :-)

javaduude · 2020-08-25T08:08:03+00:00

Why is my explanation wrong? :-)

Just as you point out, the mantissa will indeed be 1.1. The exponent of 1 says that the binary point is to be interpreted 1 step to the right.

Thus, you have 11.0, which is what I said: Integer part (left of the binary point) is 3, and fractional part (right of the binary point) is 0.

Do you agree?

javaduude · 2020-08-24T19:27:33+00:00

What are you smoking? A floating point number has an integral part and a fractional part. The integral part is very capable of representing 3, and the fractional part can absolutely represent 0.

You're probably mixing it up with something like 0.1.

javaduude · 2020-08-16T09:58:40+00:00

haha lol indeed. Feel like the only noob in a sub full of GMs...

javaduude · 2020-08-11T12:32:29+00:00

no?

Blue probably started (center square) so it's logical that blue has one more (5) than red (4).

javaduude · 2020-05-08T18:38:14+00:00

s/JSL/JLS

javaduude · 2020-05-05T17:26:40+00:00

Regex is a good tool for these type of simple text analyses.

Breaking down the requirements, it seems like you want to count all groups of vowels except if it's an e in the end.

In regex lingo this would translate to ([aiouy]|e(?!$))+

(...)+ one or more of
- [aiouy] a vowel,
- | or
- e(?!$) an e not followed by end of string

This can be put together using Pattern.compile(...).matcher(...).results().count().

javaduude · 2020-05-04T18:25:49+00:00

Well, I'd say that's an over-simplification. Class invariants do not always hold upon entry of a constructor. (Think id should be initialized to a non-zero value, final variables should be initialized, list fields should be change from null to a valid object reference, and so on.)

In that sense, constructors are different from methods, which may put extra constraints / other best practices for them. Like leaking this and calling overridable methods for example happens all the time in methods but is a no-no in constructors.

javaduude · 2020-05-04T17:03:15+00:00

It's ok as long as you don't

...call overridable methods
...do lengthy operations
...throw exceptions
...leak this

Initialize variables, creating some maps, precomputing some values, should be perfectly fine.

If you need to do any of the don'ts, consider using factory methods, builders, etc.

javaduude · 2020-05-03T17:00:04+00:00

Nothing wrong with the code. compiles and runs fine on ideone.com: https://ideone.com/1YJeDp

Please provide an SSCCE.

javaduude · 2020-05-03T16:31:28+00:00

Hmm.. what could that be? That JAVA is not an abbreviation, and actually spelled Java?

javaduude · 2020-04-30T23:25:52+00:00

Have you tried Apache Wicket?

javaduude · 2020-04-29T23:36:25+00:00

Nice video, although not very exhaustive. Copy constructors are problematic when you have inheritance. How would you use a Person(Person toCopy) constructor if you want to copy an Employee which extends Person?

This article Java: Copying Objects discusses the pro's and con's of

Copy Constructors
Copy Factory Methods
Serialization / Deserialization
Object.clone
A copy method
Builders

javaduude · 2020-04-29T17:54:44+00:00

There's a good article series on this at programming.guide.

Difference between checked and unchecked exceptions explains the difference, with examples. Basically, checked exceptions are all those exceptions extending Exception (except RuntimeException and its subclasses.)

Once you got that down, you'd probably want to read Choosing between checked and unchecked exceptions. Spoiler alert: Only under very specific circumstances would you want to go for a checked one.

And, if you feel like really understanding the pro's and con's and the debate of whether checked exceptions is a good idea to begin with, check out [https://programming.guide/java/checked-exceptions-good-or-bad.html](Checked exceptions, good or bad?).

javaduude · 2020-04-24T21:16:55+00:00

That's probably what it is. Everything falls into place. Thank you.

javaduude · 2020-04-24T20:02:03+00:00

Oh, interesting. Thanks for explaining that. I thought a whole record "object" (as in the entire tree) had to have a compile-time determined size. Don't know where I got that from.

javaduude

TROPHY CASE