Passing method arguments - by value or by reference. Theory and examples

When Java passes method arguments (parameters) by value and when by reference?
Here we put the major cases and below you will get an working example of it.

Rules:

• primitive types are passed by value (example in swapPrimitives function);
• arrays data is passed by reference (example in swapInArray function);
• reassigning the argument inside the method does not affect the variable in the caller function;
• all methods called on the arguments are called on the real object (argument variable could be changed);

We will describe the rules with swap function. Some of the methods are wrong and do not swap its arguments. After the code is the output of the program.

Code example: