Partial code cleanup based on IDE warnings

[patrickkostjens]

Based on warnings from my IDE, I did some code cleaning. The issues I fixed fall in the following categories:

• Use System.arraycopy instead of manual iteration.
• Use Collections methods instead of manual iterator or redundant array initialisation.
• Replace uses of deprecated methods.
• Replace non-looping while loops by if-statements.
• Remove redundant if-statements.
• Use Objects' equals method instead of string comparison using == or !=.
• Replace unnecessarily verbose if-statements.
• Remove redundant return-statements.

Additionally, I updated the copyright year for the files I modified.

[kno10]

Most of these changes are not good, and some may even introduce bugs, sorry.

Sometimes, the automatic recommendations of IDEs are not good.

[patrickkostjens]

I can agree with your reasoning in most of the cases. For the others, see my comments there.

I agree not all IDE recommendations may be valid and I guess it is better for me to stick with the parts of the code that I am actually using/changing since I do not know enough about the project yet. I appreciate you reviewing them anyway since it gives me a better understanding of some conventions and choices within the project.