Methods & Classes II Flashcards
What are advantages of using classes?
Links Data with code manipulation
Controls access
Three Access Modifiers & Default Access
Public
Protected - only applicable to inheritance
Private - accessible only by members of its class
Default access is public
What standard methods control access to members?
Get()
Put()
Can you pass objects to methods?
Yes, it’s common
Call by value
Copies the value of an argument into a parameter
Primitive are passed by value
Call by Reference
The reference to an argument is passed to the parameter.
Objects are passed by reference
Will changes to an object inside a method affect the original object?
Yes
Method Overloading
When two or more methods within the same class share the same name with different parameters.
E.g. Constructors
How is the correct method chosen if it is overloaded?
By matching arguments with parameters.
Recursion
A method calling itself
E.g. A factorial
What happens during recursion?
New local variables & parameters are allocated storage on the stack & the method is executed with these new variables.
Does a recursive call make a new copy of the method?
No, just the arguments are new.
What happens when there are too many recursive calls to a method?
A stack overrun
Why do recursion rather than iteration?
Some types of algorithms can be more clear & simple
How do you end the loop of recursive calls within a method?
You must include a conditional statement to force the method to return without recursion.
When can you access a class member without referencing an object?
If that member is declared static.
You don’t need to create an object prior to accessing a static member.
Ex: className.member
Static variables are essentially global variables
Which can be static - methods or variables?
Both
What restrictions do static methods have?
They can
directly call only other static methods
access only static data
do not have a this reference
When is a static block executed?
When a class is first loaded, before it is used for anything else & before objects are constructed.
Can classes be nested?
Yes - a nested class is declared within another class.
What are inner classes?
What can they access?
Non-static nested classes
They can access all variables & methods of the outer class.
What are the advantages of nesting a class?
It creates a localized class that is not known outside its block
Varargs method
A method that takes a variable number of arguments depending on its precise usage.
Varargs method syntax
int …v
Specified by ellipses …
The arguments are stored in an array referenced by the name given.
Can you combine normal & variable parameters?
Yes, but the varargs must be the last declared & there can only be one.
Ambiguity errors
Can occur due to varargs & overloading. Often exposes conceptual flaws in the code.
