Yes, there are several good ones. And they’re improving over time.

And, of course, there is an experienced instructor/developer who can detect plagiarism just by looking at the code. I know one who can detect code plagiarism from many semesters ago, and pinpoint exactly who shared their code and exactly how it was altered.

I suggest you read this answer for a guaranteed method to avoid getting caught by plagiarism detection software or by an experienced human detector like the one described above:

By the way, C and C++ are two completely separate programming languages, evolving along separate paths. Neither is or ever has been a proper subset or proper superset of the other. There are features in C, for example, which do not exist in C++. There is no C/C++ language.

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You can utilise a number of websites to evaluate the calibre of your Java code. Here are a few well-liked choices:

1. SonarQube: SonarQube is a popular platform for evaluating the quality of code and it supports a number of programming languages, including Java. Among with other capabilities, it provides static code analysis, code coverage, and code duplication identification.

2. PMD: PMD is a source code analyzer that can spot problems in your code including unnecessary variables, empty catch blocks, and ineffective code. Java is among the many programming languages that it supports.

3. FindBugs: Use the static analysis tool FindBugs to find potential issues in your code. It checks for errors including null pointer dereferences, out-of-bounds array indexes, and thread synchronisation difficulties.

4. Checkstyle: Checkstyle is a programme that verifies your code in accordance with a set of guidelines and enforces coding standards. It can verify that your code follows best practises and is readable and maintainable.

5. Codacy: A platform that provides code analysis and review services for a number of programming languages, including Java. Among with other capabilities, it provides static code analysis, code duplication detection, and code coverage.

All of these tools can assist you in finding and fixing problems in your Java code, hence raising the code's overall quality.

Regular expressions paired with a dictionary divided up into sections based on length. It’s rather hard to do, and it’s time-consuming, but you’ll find that the more you do it, the easier it becomes.

Essentially what you do is you make a Regex list for lengths of various words, and match it to the section it corresponds to. Then, you make another regex to match the letters to the ones most commonly used with it or most commonly switched up. Then, display the words that the computer thinks the user is trying to use.

You can go deeper and make it more complex to make your suggestions more accurate, but about three layers of Regex should work well enough.

No.

First, we need to define “mistake”.

It might be syntax mistake. A parser for your language would be able to diagnose that. But you’d need parsers for all those “any language” all at one site, and that would be tens of thousands of parsers. That isn’t going to happen.

It might be a type error. You’d need a parser and a typechecker for “any language”. We already can’t get parsers for everything, so that kills that. Assume you can get a parser for every language; then you need typecheckers for every language. Unlikely in practice, but might be possible in the same world in which you can get a parser for every language. Not a world I live in.

It might be an error the compiler manual says is “erroneous”. That’s language-design-committee speak for “the compiler can’t check for this (usually due to incomputability limits)”. Here you are pretty much screwed, because it means the behavior of your program at runtime can be anything, from producing the right answer by accident, or erasing all the facts from the Internet. You can only run the program and hope it does something spectacularly wrong, otherwise it might do something that is wrong but extremely subtle, like computing a million digits of Pi but getting just the thousandth digit wrong.

Lastly, it might be a mistake in the functionality, e.g., you coded a program that doesn’t compute what your specifications says it should compute. Without writing down the specification formally (you have done that, right? Uh, no? Well…) there is nothing to check your program against to see that it is wrong. No spec, no way to check your program didn’t meet the spec. You might think that writing a spec in English (or your native langauge) might be a way out, but now you need a perfect parser for the native language. Nobody knows how to build really good ones, let alone perfect ones.

OK, let’s assume you have a formal spec. Now you need to prove that your program meets the specification. We don’t have theorem provers that can do this automatically in general when your program does meet the spec, so out of luck again. It can be harder, even impossible, to prove your program does NOT meet the specification. Sometimes you can’t even find out that it is wrong.

The worst part might be a tool that could actually prove your program and the spec were inconsistent (e.g., your program really is wrong). If it did so by producing a nonconstructive proof, it might only tell you that your program is wrong…without telling you where. Ugh.

Generally, automatic debugging is hard, and you’re not likely to see it for all languages at the same place, ever. People have some success in building bug finders for some languages some of the time, and they are getting better. Slowly. If you can get such a tool for your language, it is likely to be pretty useful because most bugs are stupidly simple.

But in general, you’re pretty much screwed. Time to get out the debugger.

This is what I check during code review :
1. Does the code align completely with the business functionality ?
2. Can the code cause unintentional side effects (from a business domain point of view) ?
3. Can some parts of the code be replaced by standard libraries like Apache Commons or Google Guava ?
4. Is it possible to minimize the memory footprint ?
5. Is the code readable ? Are the variable names, method names and class names meaningful and indicative of their functionalities?
6. Is the code well equipped to handle concurrency ? Are the Date and Number formatter instances defined in a thread local context ? Is every critical section guarded by a lock ?
7. Are there enough unit tests ? Ideally I'd want every public method to have one corresponding unit test
8. Are there a few integration tests ?

I suggest using PHPStorm (paid license), Sublime Text (free/paid), Atom (free, open source), or Notepad++ (free) for programming.

• PHPStorm is very powerful IDE. If you are working with modern frameworks or large projects this tool makes your job easier by a lot. It has large choice of plugins for almost any task and smart auto-completion and hints. It might take a week or two to realise it’s full potential, but if used properly it can save a lot of time and effort.
• Sublime Text has free version that reminds you to buy it every once in a while. It has great syntax highlighting making it great general tool for programming. It has a lot of community plugins and some auto-completion. Ideal for smaller projects.
• Atom is very similar to sublime, but from feedback I hear it is somewhat slower. Biggest difference is that Atom is open source, while Sublime is closed source. This allows you to hack it to fit your needs. If this is something you need is quite subjective. (More detailed Atom vs Sublime comparison here: How does Atom compare with Sublime Text?)
• Notepad++ is even simpler tool. It gives syntax highlighting and has some plugins, but generally I wouldn’t use it for projects. It is ideal for editing config files or making small scripts. Natively it only supports windows, while other options are cross platform.

If you are learning programming I suggest using sublime or atom as they will be enough for most starting projects. Though check if you might get PHPStorm cheap/free as they offer special deals for students (if you are one).

Otherwise, if you are starting carrier in web development I strongly suggest PHPStorm. The price for it’s license is nothing compared to time you will save if you use it correctly.

The question is “How can I check the source code of open-source software such as Linux and LibreOffice?”

Projects such as the Linux kernel and LibreOffice are distributed under one of the open source licenses. You can find the base source for the versions of the packages online - and with some (perhaps a lot) of effort, you can find the PATCHES that the Linux distribution you favor made to it, as well as how they built it.

But these packages depend on the context of the build environment used - which can include an enormous number of other packages as well.

You can inspect the original source, inspect the patches (and apply the patches and inspect the result), and try to duplicate the build environment.

If by some chance, you’re able to duplicate the build environment, you MIGHT be able to produce a (nearly) identical package to what you download. (There are likely to be compilation times and dates involved that’ll result in differences.)

And once you have that, you can start inspecting the source with confidence to “check” it - whatever that means.

It’s like pulling a thread on a sweater. You’ll graduate from the simple source to the included build scripts, to the tools used by the build scripts and any libraries used, and on and on and on and on.

There will be hundreds of different coding styles and (likely) some very obscure constructs involving the many languages used.

My own experience of “checking” software - even after I’m sure I have the correct source - is that can take weeks (or months) to understand the code well enough to realize that most of the bugs I think I see are not bugs.

Mostly these days, I satisfy myself with surveying the code.

We’re talking about tens of millions of lines of code - or more, just for the two packages I mention (excluding the dependencies.)

You can spend a long time on it.

Of Course! Why not?

There are several free tools available like Grammarly, Ginger, WhiteSmoke, SpellCheck24 and so on.

Among all these, Grammarly would be the best as it can be easily installed and used. As Grammarly plug-in/add-on is available which can be added easily to your browser. This helps you in correcting your spelling mistakes, word usage, punctuation errors, Grammatical errors instantly and similarly around 250 language-related problems. For Facebook, LinkedIn, like social media comments, posts - everywhere you can have Grammarly as your support.

Try once, then you will recommend others to use it.

Mostly what the class/.java file does.

For example if I am writing a class to handle files in a unix box file i will name it as: DataListener.java, but thats me because it is waiting for some data in a specific folder, otherwise will name something like FolderDataListener or something like UtilsJMSDataListener where utils is the folder name, and handler name similar like UtilsJMSDataHandler/UtilsJMSDataParser etc etc

Another example is if I am writing a Log manager which extends my original feed back manager then i will name it as : LogFeedbackManager.java

You get the idea :)

Package names can be in small letters like “common”, “db”, “utils”,”filter”,”handlers” etc

Some so-called "grammar" checkers--which are poor at checking grammar--can read HTML documents. They simply disregard or strip out HTML coding and analyze a plain-text copy of the file. You can find out about them by checking their websites or, better, by downloading free-trial copies (most have them) and seeing for yourself.

As for spelling checkers, here's a short text full of spelling mistakes that a spelling checker won't catch:

"I live in gentile poverty, but half hardily. I get exited these days by buying my time. I make due as best I can, but though I strive with mite and mane, only once and awhile have I past mustard and towed the line. Should I get off tender hooks, buy a wide angel lens, and improve my pigeon English?"

You need a specialized checker to catch mistakes like these, which are common today because people's spelling is increasingly based more on what they hear than on what they read.

You are into a deep subject. There have been many metrics defined to evaluate SW. Carnegie Mellon University has sort of led the charge. You want to check them out. Also if you have access, the IEEE Software SIG has a lot of information. TRW has also done research in this area, see: https://pdfs.semanticscholar.org/705a/91b5fea45fff9fc7b59617cfc676da6419d9.pdf

These metrics are examples of static analysis that tries to gather information about SW without executing it. A commercial company that offers metrics is: McCabe IQ - Software Metrics Glossary

Be aware that imposing metrics on a project can have unintended consequences. For example limiting a module to 100 lines of code, forces developers to arbitrarily split modules impacting coherency. (Even if you can get an override, it is quicker to split a module than to bother.)

There is an old book on the subject that is still worth reading: Software Verification and Validation: Realistic Project Approaches (Prentice-Hall series in software engineering): Deutsch, Michael S.: 9780138220723: Amazon.com: Books