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AKGBackup - The backup program



Section 5 : Operators and Assignments

Determine the effect upon objects and primitive values of passing variables into methods and performing assignments or other modifying operations in that method.

Argument passing:

Call by value: 

This method copies the value of an argument into the formal parameter of the sub-routine. Therefore, changes made to the parameter of the sub-routine have no effect on the argument used to call it. In Java when a simple type is passed, it is passed by value.

Call by reference:

In this method, a reference to an argument (not the value of the argument) is passed to the parameter. Inside the sub-routine, this reference is used to access the actual argument specified in the call. So, the changes made to the parameter will affect the argument used to call the sub-routine. When you pass an object to a method, it is passed by reference.

When an object reference is passed to a method, the reference itself is passed by value. However, since the value being passed refers to an object, the copy of that value will still refer to the same object that its corresponding argument does.

Objects as parameters:

One of the most common uses of object parameters involve constructors. Frequently you will want to construct a new object which is initially the same as some existing object. To do this you must define a constructor that takes an object of its class as a parameter. You will also require this when you want to initialize an object of a class with an object of another class (possibly of super class).

section5-1-1 | section5-1-2 | section5-2 | section5-3 | section5-4

Sections : 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11





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