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Passing Variables into Methods- Java Passing Mechanism Explained

Every Programming Language has its own way of passing the variables into methods. There are basically two ways of passing variables- Pass by Reference and Pass By Value. The former deals with the passing of reference or pointer to particular variable and the latter involves passing a copy of the variable to the method. C supports both ways of passing and the Pass By Reference is supported b means of Pointers. Every Java Beginner ponders over “Is Java a Pass By Value?” or “Is it a Pass By reference?”  or “Both?”. Before answering the question i would like to throw light on Passing Object Reference variables and Passing primitive reference variables.

Object Reference Variables: These are the variables which refer to the object of the declared type or its subtype. Something like

Animal a = new Animal()

where  a is the reference variable

Passing Object Reference Variables:

When a object variable is passed into the method, only the copy of the Object reference is passed and not the Object itself. The bit pattern in the reference variable is copied into the method parameter. What is this bit pattern? This bit pattern is the address of the specific object in the memory (on the heap). In other words, both the caller and the called method will now have identical copies of the reference and thus both will refer to the same exact object on the heap.

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