General performance improvement:

[mosbat]

1- Replaced single element lists with java's singletonList to conserve memory.
2- Replaced empty lists with java's emptyList() to conserve memory.
3- Removed commented code.
4- Fixed classes without set package.
5- Replaced string concatenations with StringBuilders'.
6- Other minor improvements.

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 67.74194% with 10 lines in your changes missing coverage. Please review.

Project coverage is 73.46%. Comparing base (7b962a4) to head (486754a).

Files with missing lines	Patch %	Lines
...om/thealgorithms/conversions/AnyBaseToAnyBase.java	0.00%	4 Missing ⚠️
...thealgorithms/conversions/HexaDecimalToBinary.java	0.00%	4 Missing ⚠️
...orithms/datastructures/lists/SinglyLinkedList.java	0.00%	1 Missing ⚠️
...in/java/com/thealgorithms/maths/VampireNumber.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6078      +/-   ##
============================================
+ Coverage     73.44%   73.46%   +0.02%     
- Complexity     5082     5097      +15     
============================================
  Files           657      657              
  Lines         17632    17632              
  Branches       3396     3394       -2     
============================================
+ Hits          12949    12954       +5     
+ Misses         4181     4176       -5     
  Partials        502      502              

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[siriak]

Looks good, thanks!