What is the main difference between pass-by-reference and pass-by-value?
Ans:
Other languages use pass-by-reference or pass-by-pointer. But in Java no matter what type of argument you
pass the corresponding parameter (primitive variable or object reference) will get a copy of that data, which is
exactly how pass-by-value (i.e. copy-by-value) works.
In Java, if a calling method passes a reference of an object as an argument to the called method then the passedin
reference gets copied first and then passed to the called method. Both the original reference that was
passed-in and the copied reference will be pointing to the same object. So no matter which reference you use, you
will be always modifying the same original object, which is how the pass-by-reference works as well.
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If your method call involves inter-process (e.g. between two JVMs) communication, then the reference of the
calling method has a different address space to the called method sitting in a separate process (i.e. separate
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JVM). Hence inter-process communication involves calling method passing objects as arguments to called method
by-value in a serialized form, which can adversely affect performance due to marshaling and unmarshaling cost.
calling method has a different address space to the called method sitting in a separate process (i.e. separate
Java - Fundamentals
41
JVM). Hence inter-process communication involves calling method passing objects as arguments to called method
by-value in a serialized form, which can adversely affect performance due to marshaling and unmarshaling cost.
