We Keep Coding

Save values to file(e.g yml) in java

First of all this might be a dumb question and I searched for some days but didn't find an answer. So if there is an existing answer concerning my question, I would be grateful for a link.
I don't know if anyone of you ever coded Spigot, Paper or Bukkit, but there was a class called YamlConfiguration which had the following methods:
public FileConfiguration cfg = YamlConfiguration.loadConfiguration(file);
cfg.set(path.path2, "hello");
cfg.getInt/String/...(path.path2); (which obviously returns "hello")
cfg.save(file);
The produced file then looks like this:
path:
path2: "hello"
So you could basically save any value in those files and reuse them even if your program has been restarted.
I know have moved forward from Spigot/Paper to native Java and I'm missing something like that Yaml-thing. The only thing I found was a kind of a config file, where every time the whole file is overwritten, when I try to add values.
Can you show me a proper way of saving values to a file? (would be nice without libraries)

I'm missing sth like that Yaml-thing
SnakeYAML should have you covered. Without knowing anything about your use-case, it makes no sense to discuss its usage here since its documentation already does cover the general topics.
The only thing I found was a kind of a config file, where everytime the whole file is overwritten, when I try to add values.
Saving as YAML will always overwrite the complete file as well. Serialization does not really work with append-only. (Serialization is the term to search for when you want functionality like this, by the way.)
If you mean that previous values were deleted, that probably was because you didn't load the file's content before or some other coding error, but since you don't show your code, we can only speculate.
Can you show me a proper way of saving values to a file?
People will have quite different opinions on what would be a proper way and therefore it is not a good question to ask here. It also heavily depends on your use-case.
would be nice without libraries
So you're basically saying „previously I used a library which had a nice feature but I want to have that feature without using a library“. This stance won't get you far in today's increasingly modular software world.
For example, JAXB which offers (de)serialization from/to XML was previously part of Java SE, but has been removed as of Java SE 11 and is a separate library now.

adding to my methods quick documentation description (android studio)

Is there a way to add to a description in a methods quick documentation? I have some methods I created that I plan to use later down on the line and want to add to its quick documentation to remind myself what the method is for in case I forget, without having to go into the method itself to read comments describing what the method does.

Is there a way to add to a description in a methods quick documentation?
The best way to document your methods is giving them (and their parameters) meaningful names.
Comments should not repeat what the code expresses itself. But no generator will ever look into your head to extract your intention from there. It rather will analyze the code and build the comment based on what's already written.
Therefore (meaningful) comments cannot be generated.
There are two valid reasons why you should write comments (yourself):
Interfaces
Interfaces need (JavaDoc) comments to explain the contract behind the method, to express the callers expectation as a help for the implementer.
odd ball solutions
Is there something in your code done in an unusual way?
Then add a comment why you did it so.
There might also be comments for legal reasons e.g. copyright marks, license texts and alike. But there should not be any other comment then this, especially nothing generated.

If you want to put comments in a single place for an entire project, or keep comments co-located with a set of files, try using a README. These are usually written in Markdown for easy conversion to beautifully formatted HTML for easier reading. Try an online markdown editor.

Java - Trying to plan the layout of a programs classes

I'm having a bit of trouble figuring this out so if you can help that would be great.
I have written a bit of code that gets a list of URLs from a sitemap. I then go each page, scrape all the links, and then test their status(200,404, etc).
I am using HttpClient. I have it all working OK but as I am new to Java I reckon my code is a complete hack/maze and I could most likely get far better performance if it was organised correctly. So what I have is
Main class - This builds the gui
Parse the sitemap class - This parses the sitemap and get a list of the urls.
Class called PingURl - I'm sure my above is poor but this is the bit I reckon is worst. This class opens all the urls, scrapes them for links, then tests the links for their status and returns it. I presume this class should be broken down? Most importantly I think I should be isolating the testing of the links in it's own class, so it would be easy to implement threads later on?
Basically I'm looking for advice. If someone could help me with laying out the project a bit better. Secondly I believe this is my weakest area so to improve I need to learn more about this, I don't even know what to call this(design/layout problem?). Can you also recommend resources to learn more about this?

Java is a language which IMO, embodies good OO design. Designing with OO in mind is very effective.
http://java.sun.com/developer/onlineTraining/Programming/BasicJava2/oo.html
In terms of your problem, I think it works pretty well. You are kind of following a Model-View-Controller pattern: http://www.codinghorror.com/blog/2008/05/understanding-model-view-controller.html
I can't tell you how to design your code, but I will tell you how I would do it if I were presented with the same problem:
I would get a class to represent a hyperlink. In that class there would be the hyperlink that has been scraped, and a getter and setter. As well as a boolean value and a ping function. That means that if I create a "hyperlink" object, then I can invoke ("ping") on that object because it is part of that class. That means that the ping function simply sets the boolean that represents connectivity.
That way, your parser basically gets a page, and for each link it finds, it creates a new "hyperlink" object based on your own "hyperlink" class. And puts it in an array. So once your parser executes you get an array of pointers to hyperlinks.
Then all you have to do is invoke the ping function on each one to see if it is there.
I think this design is the best because it scales from doing one hyperlink test to doing 1000 quite easily.
There is soooo much stuff out there about design, there are countless principals as well. There is never one absolute way to solve a problem. But the more experience you get, and the more you read up on design patterns and models the better you will get at it :)

Evaluating creation of GUI via file vs coding

I'm working on a utility that will be used to test the project I'm currently working on. What the utility will do is allow user to provide various inputs and it will sends out requests and provide the response as output.
However, at this point the exact format (which input is required and what is optional) has yet to be fleshed out. In addition, coding in Swing is somewhat repetitive since the overall work is simple though this should be the safest route to go as I have more or less full control and every component can be tweaked as I want. I'm considering using a configuration file that's in XML to describe the GUI (at least one part of it) and then coding the event handling part (in addition to validation, etc). The GUI itself shouldn't be too complicated. For each type of request to make there's a tab for the request and within each tab are various inputs.
There seems to be quite a few questions about this already but I'm not asking for a 3rd party library to do this. I'm looking to do this myself, since I don't think it'll be too overly complicated (hopefully). My main consideration for using this is re-usability (later on, for other projects) and for simplifying the GUI work. My question is: are there other pros/cons that I'm overlooking? Is it worth the (unknown) time to do this?
I've built GUI in VB.NET and with Flex3 before.

XML is so 2000. It's code, put it in real source files. If it really is so simple that it could be XML, all you are doing is removing the XML handling step and using a clearer syntax. If it turns out to be a little more complicated than you first expected, then you have the full power of your favourite programming language to hand.

In my experience, if your layout really is simple, something like the non-visual builders in FormLayout can lead to really concise code with a minimum of repetition.

If you have to specify the precise location of every control you might look at a declarative swing helper toolkit that can minimize boilerplate and simplify layout. Groovy supports this as does JavaFX, and both are simple library extensions to Java (give or take).
If the form is laid out in a pattern, using a definition file in a format like XML or YAML will work. I've done that and have even set up data bindings in that file so that you don't even have to deal with listeners or initial values...
If you are sure you want XML, I'd seriously consider YAML though, it's really close but instead of:
<outer>
<inner a=1> abc </inner>
</outer>
I think it's a lot more like:
outer
inner a=1
abc
(I may have that a bit wrong, but that's close I think. Anyway, you should never force anyone to type XML--if you are set on XML, provide a GUI with which to edit it!)

Domain name interpretation utility for java

I find myself with a need for a java utility for taking a fully-qualified hostname, and producing the domain name from that.
In the simple case, that means turning host.company.com into company.com, but this gets rapidly more complicated with host.subdomain.company.com, for example, or host.company.co.uk, where the meaning of "domain name" gets a bit fuzzy. Throw in complications with the definition of SLD and ccSLD, and it gets messy.
So my question is whether there's a 3rd-party library out there that understands these things and can give me sensible interpreations.

Mozilla regularly maintains the rules that it uses in its browser for cookie security in a format that can be parsed and used by others:
http://publicsuffix.org/
Searching Google, there are probably Java libraries that can parse the list, but I don't know the quality of any of them.

I don't think such a thing exists, since it's an adminstrative rather than technical issue, and a very multi-lateral one, at that.
If you end up rolling your own, this page on the Mozilla wiki looks like a good starting point, with lots of references. Looks like a major headache though. Just look at the rules for Japan. Ouch.

Not sure if it's for the same purpose, I do something similar in my code. When I set cookies, I want to set the domain as close to top as possible so I need to find the domain one-level lower than a public suffix. For example, the highest domain you can set cookie for host.div.example.com is .example.com. For host.div.example.co.jp is .example.co.jp.
Unfortunately, the code is not in the public domain. It's very easy to do. I basically use following 2 classes from Apache HttpClient 4,
org.apache.http.impl.cookie.PublicSuffixFilter
org.apache.http.impl.cookie.PublicSuffixListParser
I forgot the exact reason but we had to make some very minor tweaks. You just walk the domain from top to bottom, first valid cookie domain is what you need.
You need to download the public suffix list from here and include it in your JAR,
http://mxr.mozilla.org/mozilla-central/source/netwerk/dns/src/effective_tld_names.dat?raw=1