iluwatar / 30-seconds-of-java Goto Github PK

http://www.baeldung.com/java-compress-and-uncompress chapter 5

Bit Manipulation Concepts:-

• Find the element that appears once
• Program to swap two numbers without using the third variable

and more.

It's nice to see the snippets on the web page https://java-design-patterns.com/snippets.html, but in a sense they are not complete since you can't see the imports etc. So it would be great to have a link in each snippet pointing to Github code - to make it easier for the reader.

The current palindrome check snippet uses O(n) space, it can be improved to use O(1) space with this simple algorithm:

  public static boolean isPalindrome(String s) {
    for (int i = 0, j = s.length() - 1; i < j; i++, j--) {
      while (i < j && !Character.isLetter(s.charAt(i))) {
        i++;
      }
      while (i < j && !Character.isLetter(s.charAt(j))) {
        j--;
      }

      if (Character.toLowerCase(s.charAt(i)) != Character.toLowerCase(s.charAt(j))) {
        return false;
      }
    }

    return true;
  }

http://www.baeldung.com/java-compress-and-uncompress chapter 3

In error detection, the Damm algorithm is a check digit algorithm that detects all single-digit errors and all adjacent transposition errors.

https://en.wikipedia.org/wiki/Damm_algorithm

New snippet how to convert an InputStream to String using only core Java libraries. See https://stackoverflow.com/questions/309424/how-do-i-read-convert-an-inputstream-into-a-string-in-java

http://www.baeldung.com/java-compress-and-uncompress chapter 4

https://sonarcloud.io

After #20 we can update Travis build to JDK 11.

Github's instructions: https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors

The codebase has been written for Java 8. Now that we have taken Java 11 to use the snippets should be refactored to use Java 11 style and features.

For checklist, see https://github.com/iluwatar/java-design-patterns/wiki/16.-Java-11-Transition chapter "After the transition".

To show the code snippets correctly on the Korean website, we need a translation of README.md. The result of the translation should be placed to localization/ko/README.md.

Acceptance criteria

• README.md translated to Korean

Hello, I running ./gradlew clean build but 2 test faild. May it occure only on my system?
More detail:

86 tests completed, 2 failed

1. ListFilesInDirectorySnippetTest > testListFilesInDirectory() FAILED
   org.opentest4j.AssertionFailedError at ListFilesInDirectorySnippetTest.java:48

2. InputStreamToStringSnippetTest > testInputStreamToString() FAILED
   org.opentest4j.AssertionFailedError at InputStreamToStringSnippetTest.java:52

The Luhn mod N algorithm is an extension to the Luhn algorithm (also known as mod 10 algorithm) that allows it to work with sequences of values in any base.

https://en.wikipedia.org/wiki/Luhn_mod_N_algorithm

Create new snippet that returns true if all array elements are equal.

https://en.wikipedia.org/wiki/Prime_number

Since we have transitioned to Java 11 we should start using Java's new HttpClient. In this task we update the Http GET snippet to use it.

Links:
https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html

To show the code snippets correctly on the Chinese website, we need a translation of README.md. The result of the translation should be placed to localization/zh/README.md.

Acceptance criteria

• README.md translated to Chinese

The project currently uses a custom checkstyle configuration in config/checkstyle.xml. In this task let's upgrade Checkstyle and start using the built-in Google checks instead of a custom configuration.

Acceptance criteria

• Checkstyle updated to the latest version
• Checkstyle uses Google checks instead of the custom config

To make it easier to quality control the incoming pull requests, we should have a CI build.

Acceptance criteria

• Github Actions based CI-build has been created
• Builds the main branch when it changes
• Incoming pull requests are checked

HTTP post in plain Java. Use of Java 11 HttpClient is preferred.

Links:
https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html

I would like to add a new iterative fibonacci solution and a recursion factorial solution

Hello, In the HttpPostSnippetTest class, the testHttpPost method is failing. This method is intended to test the behavior of an HTTP POST request, but it's currently failing for some reason.

Currently there are no instructions how to contribute to the project. Probably we can start with short instructions in the README.md.

Luhn algorithm is used to validate a variety of identification numbers https://en.wikipedia.org/wiki/Luhn_algorithm

Can provide a search bar so that if user want for a specific algorithm, user can search it.

In this issue we take Checkstyle to use with google_checks.xml ruleset

It is a procedure used to find the greatest common divisors of two positive integers.

Provide snippet that calculates Elo rating https://en.wikipedia.org/wiki/Elo_rating_system

I just realized that the library is one big file, this will be problematic each time this file is modified.

Can we separate each source code as one file?

I think, this is the best we can do to avoid merge conflicts. For example, lines 5-10 is for a specific code, now two pull requests change the same file, in one pull request, the code was changed before lines 5-10, so now, the mentioned specific code 5-10 will be adjusted. The second pull request will have a merge conflict because of that.

And as you can see, if someone will use a specific code in that library, he/she will have a hard time finding all the specific imports for that specific source code, unlike when the source code is just one file, for example, a code for binary search, he/she can simple get it as one file.

Provide snippet that calculates Levenshtein distance https://en.wikipedia.org/wiki/Levenshtein_distance

Provide snippet that checks if word is anagram of another word

https://en.wikipedia.org/wiki/Anagram

I would like to add more algorithms in Array section.

http://www.baeldung.com/java-http-request

The method could play a sound file. No external libraries should be used.

See for example https://30secondsofcode.org/

Currently we are using Java 8. In this task we migrate the codebase to Java 11.

The Verhoeff algorithm is a checksum formula for error detection developed by the Dutch mathematician Jacobus Verhoeff.

https://en.wikipedia.org/wiki/Verhoeff_algorithm

https://en.wikipedia.org/wiki/Quicksort

For example, given the number 15 the output of the method is 1111. Another method is able to convert binary string such as 1111 to integer 15.

I would like to add finding the mean, median and sum to the arrays section.

• Generate a random number between x and y
• Throw dice e.g. 3d6

I would like to add BinarySearch Algorithm in the Algorithm section

The method can play a video file

Add methods for converting integers to hex and hex to integer

While the snippet GetAllMethodsSnippet uses a traditional for loop, and there's nothing wrong with that, I think it might be a good idea to swap for using streams, just because the others in same category (Class) do so.