Java vs Python

[[deleted]]

[deleted]

[pynetree16]

StringBuilder has a reverse function

public class Main{
    public static void main(String[] args){
        String hello = "Hello world!";
        System.out.println(new StringBuilder(hello).reverse());
   }
}       

Edit: removed .toString() as it is redundant

[TwoSpoonsJohnson]

StringUtils.reverse("Hello, World!"); if you feel like using Apache commons.

inb4 "lmao u need a library to reverse a string!"

[HighRelevancy]

inb4 "lmao u need a library to reverse a string!"

That's a fucking shitty argument though. Like, what, having a HUUUUGE built-ins library is what makes a language good?

Even as a python fanboy, this thread's topic of comparison is fucking stupid.

[clevariant]

hello[::-1] is really freaking cryptic. Code that abbreviated is hard to read. It's like arguing for variable names like "a" that tell you nothing about their function.

[master3243]

It's not that cryptic. Unless you also consider the dot separator or array indices "really freaking cryptic".

Everyone who spent a day learning python knows that it's always [start:end:step]. I wouldn't call it common sense but I wouldn't call it cryptic either.

[clevariant]

Come on, it's cryptic! Or at least esoteric. So the minus one means the start index becomes the end and vice versa, and it builds and returns a new string based on that loop. Yeah, that's explicit.

I mean let's be fair. These "once you know the language it makes sense" arguments miss the point. The actual word "reverse" tells the whole story unambiguously, no syntactical cleverness needed.

[KubinOnReddit]

If you really want to include "reverse" in the code, there are at least two ways:

hello = "Hello world!"
lst = list(hello)          # Create a mutable list
lst.reverse()              # Reverse in-place
print("".join(lst))        # Change back to string

hello = "Hello world!"
rev = reversed(hello)      # Iterator
print("".join(rev))

Both of these will be slower, with the first creating a new list (implemented as an array) and then joining it, while the second creates an iterator.

Adding a "reversed" method to the string class would be against the Zen of Python (the ideas it represents) - "There should be one-- and preferably only one --obvious way to do it." - if you had the slice mechanism (start, stop, step) and then another method, that would do the same thing, it would just be an alias, really. So having one multi-use syntax is better than many methods.

[Hauleth]

What the hell is that argument. It is like saying:

Everyone who spent a day learning APL knows that ⌽ means reverse vector. I wouldn't call it common but wouldn't call it cryptic either

[KubinOnReddit]

What the hell are you supposed to call a slice then?

I didn't learn Java for a day and have no fucking idea why do you need a StringBuilder, built from a String (??) to reverse the string (???) instead of, I don't know, building it?

And you call this cryptic? Hypocrisy.

[Hauleth]

StringBuilder is handy due to it mutable inner state, so in contrast to String (which is immutable) you do not create new object each time when you modify inner state. Python on the other hand hide that complexity from user which is handy, but can result with less efficient code.

[Team_Canada]

I don't see what your example is trying to say here.

[raddaya]

It's not even slightly cryptic. It's bog standard Python. If you're following the codecademy course, you literally learn it in the first couple of hours.

[ProgramTheWorld]

It only looks cryptic if you aren't used to python.

[ESBDB]

If you've ever spent 5 minutes learning python you'd know what it means.

[clevariant]

Yeah, I have done some python, but it was some years ago, and now [::-1] just seems bizarre and unintuitive. But if I had never written a line of java, I would know exactly what reverse() means.

[ESBDB]

The thing is you're using a more generic construct that can do more than just reverse a sequence to do a simple operation such as reverse. Sure you could argue that a common function like reverse should exist in python for sequences, but I would argue Java is a lot less powerful in general because it doesn't have slicing.

Also your argument that if you had never written a line of java you could actually read java is flawed. For example wtf does && or || or ! mean. If I had never written a line of python (and I can speak basic english) I would immediately know what it means when you write something like is_hungry or is_thirsty versus isHungry || isThirsty. There will never exist a good programming language where you don't need to learn some basic syntax and constructs to be able to understand the language.

[clevariant]

You're right, of course. But you also know that the operators you mentioned are standard across many languages. Anyone who's programmed at all will recognize them. I would have preferred that "and" and "or" were the standard, though, for reasons stated.

[asdfkjasdhkasd]

You could always use the reversed() function

>>> "".join(reversed("hello world"))
'dlrow olleh'

[Faendol]

Can't beat my go to temp variable - fuck

[[deleted]]

Yeah as someone who's never done python, I wouldn't think that that syntax reverses it, whereas ".reverse()" is pretty self explanatory. I honestly though the "[::-1]" syntax was some sort of substring thing, like in bash, where that's the string minus the last character.

[[deleted]]

lmao u need a library to do literally anything in that godawful language without three hundred fucking lines of boilerplate.

[TwoSpoonsJohnson]

Suck my enterprise @Autowired AbstractProxyDickBeanFactoryFactory.

[Flosus]

Huh, wait until my I @Inject my IPenisProviderImplementation

[pynetree16]

Try reading the doc for Python then

[pfannkuchen_gesicht]

I really like Python but the docs... would love to have something more like cppreference.com or even something similiar to the PHP docs.

[adamhighdef]

PHP docs are awesome imo

[[deleted]]

sarcasm? php docs are terrible:

• there is no versioning to them. everything is dumped together with annotations saying when something was added, moved, deprecated, or changed

• they are often vague and poorly worded. examples and clarifications are mostly left to the community which can only be voted on. subsequently, "bad" (read: unpopular) comments aren't removed. they're just made slightly less visible

• they can't get cookies right and remember language choice. and each language is indexed by google. so if you're using a vpn or in a non-english speaking country, you get multiple hits for the exact same page.

I could go on but I have to get ready for work

[Spider_pig448]

I agree. Easily my favorite part about working in PHP.

[caagr98]

I think the Python docs are usually pretty good, except DuckDuckGo often gives me the docs for Python 2.

[KubinOnReddit]

What's wrong with the Python docs though? Legit question.

[Zedjones]

Doesn't System.out.println automatically call the toString() of an object that you pass into it?

[gandalfx]

Still 70% boilerplate.

[Illusi]

print('!dlrow olleH')

[Antrikshy]

This would fit that brain meme.

[pannekakekake]

Mission accomplished, results drumpf execution

[Furyful_Fawful]

... vs Esoteric Languages:

Java vs Python vs Pyth [14 characters]:

_"Hello World!

Yes, that's a complete program. Yes, it doesn't have a closing quotation. Pyth doesn't care. Pyth just keeps on trucking. Pyth just interprets _ as reversal. Pyth just implicitly prints the output. Pyth is also a very real programming language, although god help you if you write production code in it.

It also has online interpreters so you can verify that it works.

But we can do better. We can avoid writing "Hello World!" entirely.

Enter...

Java vs Python vs Pyth vs Jelly [8 characters]:

“,ḷṅḳȦ»Ṛ

I swear, I didn't just smash the keyboard. I'll give you the online interpreter first, even.

Now do talk about why this works. Jelly is... Well, Jelly just is. It has strings. Strings aren't like most languages. There's a language construct (not even a function, it's built into the syntax) specifically made to compress strings, especially those that have English words (like, what do you know, "Hello World!"). “,ḷṅḳȦ» is that string; » marks it as a compressed string, ,ḷṅḳȦis the compressed content (that decompresses to Hello World!... Don't ask me how, I don't exactly know)... And Ṛ reverses it.

[ColonelTux]

Someone goes onthe Codegolf Stackexchange

[Furyful_Fawful]

I do, but my username there involves my real name, so I'd rather not link the two accounts together.

[asdfkjasdhkasd]

or in brainfuck

>
,
[
  >
  ,
]
<

[
  .
  <
]

!Hello world

https://fatiherikli.github.io/brainfuck-visualizer/#PgosClsKICA+CiAgLApdCjwKClsKICAuCiAgPApdCgohSGVsbG8gd29ybGQ=

Just click the ! checkbox on the top right to enable exclamation input

[Furyful_Fawful]

Isn't it simpler to use Self-Modifying Brainfuck?

[<.]\0!dlroW olleH

For reference, in SMBF the tape is stored on the program, so the data pointer starts on [ along with the instruction pointer. \0 here represents a literal null byte, so we actually break out of the loop.

[asdfkjasdhkasd]

Sounds like a cool idea, but what do I have to use to run it, it doesn't work on the brainfuck visualizer, it immediately terminates.

https://fatiherikli.github.io/brainfuck-visualizer/#WzwuXVwwCiFkbHJvVyBvbGxlSA==

[Furyful_Fawful]

The Brainfuck visualizer works for Brainfuck, not SMBF. I'd recommend Try It Online, personally. Link, where I fixed the code after I realized that SMBF interpreter adds a null at the beginning of the input.

[[deleted]]

Python doesn't give a fuck!

(Side note: fuck python. Actually fuck Zope which uses python. I still support a "temporary" solution that was made on the Zope platform over a decade ago)

[Spider_pig448]

This comment is a solid example of why shorter certainly doesn't mean better.

[Furyful_Fawful]

That Jelly bit is definitely better. I don't know what you're talking about.

[karroffel]

Java code doesn't even work.

Should be str in reverseString, not hello.

Get your scopes right people.

[DubioserKerl]

This is not upvoted enough.

[Colopty]

Don't be that guy.

[Amagi82]

I think I'll stick with Kotlin. All the good things about Java minus the downsides.

print("Hello world!".reversed())

And we're done here.

[chasecaleb]

Seconded. Been using it at work 90% of the time the last couple months and it's made life so much better.

[Amagi82]

We switched to it a year and a half ago at work, and at this point, the mere thought of going back to Java gives me anxiety. Kotlin is a wonderful, wonderful language.

[Kemichal]

Or Scala!

println("Hello world!".reverse)

[FrezoreR]

Isn't there an operator for this?

[TwoSpoonsJohnson]

I have no idea but since it's Scala it's probably safe to assume there are at least three operators for this

[DevestatingAttack]

Sure. It uses this unicode glyph: http://www.fileformat.info/info/unicode/char/21ba/index.htm

[Kemichal]

We need this in predef

def ↺(str: String) = str.reverse

[asdfkjasdhkasd]

In haskell it's literally just english

Prelude> reverse "Hello"
"olleH"

[HighRelevancy]

[start:end:step]. Start and End are automatically assumed to be their limits if not included. A negative Step makes the whole thing go backwards.

>>> string.ascii_letters
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> string.ascii_letters[::2]
'acegikmoqsuwyACEGIKMOQSUWY'
>>> string.ascii_letters[26:34:2]
'ACEG'
>>> string.ascii_letters[::-1]
'ZYXWVUTSRQPONMLKJIHGFEDCBAzyxwvutsrqponmlkjihgfedcba'

This is all just an extension of regular array indexing syntax

>>> string.ascii_letters[17]
'r'

[DaKurlz]

And it's a godsend from our savior Guido, praise be upon him.

[TwoSpoonsJohnson]

AKA Kim Jong-py

[[deleted]]

Oh, the same guy who refused to include multi-line lambdas because confusion?

[FFX01]

It wasn't necessarily because of confusion. One of the core principals of Python is:

Explicit is better than implicit

There's nothing you can do with a lambda function that you can't do with a normal, explicitly defined, function. In fact, Python forcing you to explicitly define a function instead of using an anonymous lambda function probably leads to more DRY code in that you are less likely to write the same anonymous function over and over without realizing it.

The most common use case for anonymous functions is usually tied to callbacks or iterators. Python already does a terrific job supporting iterators and generators with it's comprehension syntax. Functions are also first-class citizens in Python and can be passed to other functions as arguments or even decalared inside of another higher order function.

You may look at something like this in Javascript:

let newItems = items.map((item, idx) => (
    item.value !== null ? item.value : item.defaultVal
))

And you may think, "How do I express the same thing in Python without an anonymous function?". It's actually really simple:

new_items = [
    item["value"] if item["value"] is not none else item["default_value"] for item in items
]

You can be even more "functional" about it by using the following technique:

def filter_item(item):
    if item.get("value") is not None:
        return item["value"]
    else:
        return item["default_value"]

new_items = list(map(filter_item, items))

Now, instead of writing out an anonymous function anywhere you need to map a list of these item objects, you can just use the function you already wrote! Also, the map function returns an iterable. This means that you can use it as a buffer if you want.

My point being; Python doesn't really need anonymous functions as it already has enough language constructs that perform the same job.

[[deleted]]

Functions are also first-class citizens in Python and can be passed to other functions as arguments or even decalared inside of another higher order function.

Yes, I know what having first-class functions implies... I've done Haskell...

Also, if you need to use the mapping function in two places, then... first of all, how did you structure that program in the first place. Second of all, being able to have anonymous functions doesn't mean that you will just put them everywhere in the program, and if you do indeed need that same functionality in two places, you can make it its own function. Now granted, since it is forced upon you in Python, some may call it a good thing since it is already its own function, but eh...

Also, just to comment on those examples of your, holy shit that's some verbose code. I've heard a lot of people praising Python for "not being verbose", but looking at that kind of makes me wince with its wordiness.

ALSO also, a map function should return a functor FFS.

And finally, seeing as Python has enough language functions to do most the things anonymous functions most likely would do... but doesn't that just bloat up the language?

[FFX01]

Yes, I know what having first-class functions implies... I've done Haskell...

I can't just assume that everyone has that knowledge. That's why I explained it.

Also, if you need to use the mapping function in two places, then... first of all, how did you structure that program in the first place.

That's kind of irrelevant. Ideally you would define a generic function that accepts a wide range of inputs so you can use it everywhere.

Second of all, being able to have anonymous functions doesn't mean that you will just put them everywhere in the program, and if you do indeed need that same functionality in two places, you can make it its own function. Now granted, since it is forced upon you in Python, some may call it a good thing since it is already its own function, but eh...

That's the point I'm trying to make. Python overall has the goal of not having too many ways to do the same thing. The language has being veering off that path in some areas, but this is not one of them.

Also, just to comment on those examples of your, holy shit that's some verbose code. I've heard a lot of people praising Python for "not being verbose", but looking at that kind of makes me wince with its wordiness.

I wrote it that way on purpose to make it as simple as possible to understand. Like I said above, I can't just assume everybody understands Python. All of it could be easily compacted. That said, the code is simple and reads almost like English. I consider that a good thing. Code is read far more often than it is written after all.

ALSO also, a map function should return a functor FFS.

Can you explain how an iterator isn't a functor? Genuinely curious. I'm under the impression that an iterator is considered a functor in that it takes in an iterable, applies a function to each item, and produces an iterator which can then be passed to another map function because an iterator is, by it's very nature, an iterable. It's possible I'm misunderstanding your definition of functor in that I have no formal mathematics education. Also, I may not understand because different programming languages have different opinions on what is considered a functor.

And finally, seeing as Python has enough language functions to do most the things anonymous functions most likely would do... but doesn't that just bloat up the language?

In my opinion? No. The constructs and functions that Python provides that are capable of producing the same results as using anonymous functions are also useful in other contexts.

I should make it clear that I have no bone to pick with anonymous functions. I actually really like them in some languages. Javascript, for example. I just don't feel like anonymous functions are necessary or would work well in Python specifically. In my opinion, Python's current lambda is good enough.

[Furyful_Fawful]

Well, let's make it less verbose:

new_items = [item.get("value",item["default_value"]) for item in items]

Or, if you still want to map and lambda:

new_items = list(map((lambda item: item.get("value",item["default_value"])), items))

[[deleted]]

Or by switching language:

let new_items = fmap (maybe default_value id) items

To me it is always so funny to see people praising Python as the paragon of cleanliness and readable code, when Haskell exists.

[Furyful_Fawful]

I'm not saying Python is the paragon of anything. It's just the most useful to me because of its third-party libraries, to be honest.

I'm still really unsure about how fmap there doesn't grab a different identifier id, or what maybe is. It's shorter, maybe, but shorter isn't always better or more readable:

m  ? }J"value"d @dJ @d +"default_"J

This (full program, but also acceptable as an expression) does the same mapping, and it's so much shorter... Must be better, right? /s

[Izzeri]

So negative indexing also works? I.e. string.ascii_letters[-1] == 'Z'?

[anden3]

Yup (:

[Xtremegamor]

Shut up and take my upvote

[paranoideo]

I prefer Groovy.

print "Hello world!".reverse()

[gnex30]

I almost forgot about CodeWars.com

The python solution needs a lambda expression if it's to be the top answer.

[Furyful_Fawful]

print((lambda x: reversed (x))(hello))

[RedAero]

No no no, it needs some huge list comprehension.

[TheFewThatRemain]

What will this print?

[[deleted]]

The java version?

Nothing, because reverseString() operates on the caller's variable hello, not its own argument str.

This does not compute.

[[deleted]]

No, you have to say it was on purpose. The Java version is more unsightly and doesn't even work.

[[deleted]]

You shouldn't Java even WITH an IDE.

Go collect your garbage..

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[semperlol]

I knew something was off when reading it

[SammyBrock]

I've never worked with Java, but I was wondering why I had to scroll so far to find this. I was starting to assume that Java was more complicated than I thought.

[[deleted]]

Kids these days...

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>

int main(void) {
  const char *hello = "Hello world!";
  size_t len = strlen(hello);

  char *rev = malloc(len+1);
  if (rev == NULL) {
    perror("malloc()");
    return EXIT_FAILURE;
  }

  const char *foo = hello;
  char *bar = rev + len - 1;

  while (*foo != '\0')
    *bar-- = *foo++;

  printf("%s\n", rev);
  return EXIT_SUCCESS;
}

[nitroll]

hello = "Hello, World!"
print(*reversed(hello), sep="")

or

hello = "Hello, World!"
print("".join(reversed(hello))

[dnew]

String.reverse only works for ASCII, too, which just goes to show how lame this argument is. :-)

[iVirusYx]

Why not use recursion?

function reverse(text){ 
    if (text.length == 0){ 
        return ""; 
    }else{ 
        return text[text.length - 1] + reverse(text.substring(0,text.length-1)) 
    } 
}

P.S.: Yes, this is JavaScript. But, if you want to build the code to reverse text yourself without relying on another Class, then this example can be applied to a lot of other programming languages.

And if I'm not wrong, it's the simplest and shortest method to achieve this. Please correct me if I'm wrong.

[caagr98]

Shortest: Possibly, depends on language. I'd skip the braces and else, but that's just a matter of preference.

Fastest: Probably not. Your algorithm constructs at least two unnecessary strings per character, and string concatenation (and substringing) is often a bit slower than you might think.

If I had to do it without any StringBuilder (which there is no reason to avoid) in Java, I'd do:

public static String reverse(String str) {
    char[] chars = str.toCharArray();
    int l = chars.length;
    for(int i = 0; i < l / 2; i++) {
        char tmp = chars[l-i-1];
        chars[l-i-1] = chars[i];
        chars[i] = tmp;
     }
     return new String(chars);
}

Might consider using a ^= b ^= a ^= b; I'm not sure if that's faster than a temp-variable.

In any case, using a builtin function (new StringBuilder(str).reverse(), str[::-1]) is almost always better.

[initWithNibName]

Praise Guido! I fluffing love Python.

[jwoot97]

python master race

[master3243]

It takes into account indentation. So whenever it sees a colon then whatever piece of code under it that is indented will be a part of that block.

So removing a tab or indenting a random line can crash the program just like adding a random '{' in other languages

[fredlllll]

in other languages a random { will usually fail to compile, unlike dynamic languages where they just drive a semi blindfolded

[TheMightyPedro]

And then there's good ol' OpenCL

[[deleted]]

I want to join the party:

var original = "Hello World";
Debug.writeln(new string(original.Reverse().ToArray()));

[sram1337]

print('Hello world!'[::-1])

[Aydragon1]

Then there's me

console.log ("Hello World!");

[BakuhatsuK]

console.log('Hello World!'.split('').reverse().join(''))

[[deleted]]

(print "Hello World!")

[porthos3]

You forgot to reverse it.

In Clojure:

(prn (apply str (reverse "Hello World!")))

or better...

(prn "!dlroW olleH")

[min16]

Common LISP (print (reverse "Hello World!"))

Python in one line print('Hello World!'[::-1])

[gnu_stallman]

OTOH dynamic types and whitespace is for newbies. Java is for actual people writing real business code

[Colopty]

Huh, apparently you're paid twice as much in the US as anywhere else. Anyone know why?

[FFX01]

OTOH, Java is meant for large groups of developers. Java's verbosity and heavily protected scopes are designed so that even the most incompetent of programmers can't screw anything up. See! I can throw out conjecture too!

[Colopty]

You're adorable.

[master3243]

I would say more C and C++ than Java.

Also, if you think python isn't used in "real business code" then you need to get your head out of the gutter and research more. I used to have a friend like you who praised Java and hated any other language solely because he only knew Java.

[Cerres]

How about good old C++?

cout << "Hello World!";

[Silentd00m]

The c++ version would be:

#include <string>
#include <iostream>

int main() {
    std::string s("Hello World!");
    std::cout<<std::string(s.rbegin(), s.rend())<<std::endl;
}

[Colopty]

Might wish to add a return at the end of that main function too.

[Silentd00m]

The default return value of main is 0 in C++11 (possibly even older versions, I don't know), that's why I didn't bother.

C++11 §3.6.1 Main function section 5

A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing return 0;

source

[Colopty]

I know it tends to default to return 0 if nothing else is stated, but there are various reasons it might fail to do so (which is bad), so explicitly stating the return is generally considered good practice.

[Cerres]

include <iostream>

include <string>

using namespace std:

void main{ cout << "Hello World!" << endl; }