[Data Structure (Java)] Generic

https://crane206265.tistory.com/74?category=1076637

[Data Structure (Java)] Array

원래는 SLL을 다룰 차례이지만, SLL implementation을 위해 generic부터 공부하고 가도록 하겠습니다.

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Data type - Primitive type / Wrapper type

primitive type	wrapper type
boolean	Boolean
char	Character
double	Double
int	Integer

 

Primitive Type

- 8 primitive types : int, long, double, float, boolean, byte, short, char

- declared and provided essentially by Java

- allocated on stack memory

 

Wrapper Class

- to handle primitive types as a class

- can be used for generic type

 

 

and, these are base to understanding generic.

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Generic

data type specified by (external) user (not be specified with declaration)

--> "specifiable data type"

 

Operator : <type parameter>

- how to pass a generic type

- should receive wrapper class

- pass the received wrapper classes in order

- if empty set of <> ("diamond operator") : rely on type inference (specified by the passed parameter)

 

ex)

public class ClassName<A, B> {
    A var1;
    B var2;
    public ClassName(A a, B b) {
    	var1 = a;
        var2 = b;
    }
    ...
}

 

 

* array creation with generic

//Example : array

private E[] data = new E[capacity]; //(X)
//Java does not allow the creation of arrays of generics

private E[] data = (E[]) new Object[capacity]; //(O)