Thinking in Java extract notes

/**

*
<P> title: </P>

*

*
<P> Description: </P>

* Both combination and inheritance allow setting sub-objects in the class. The combination is displayed and the inheritance is implicit.

* A combination is usually used when you need to use functions in the class instead of interfaces.

*

* You shall reserve the right to "change underlying implementation ".

* Why is "upward transformation" required "?

* The export class is the superset of the base class. That is to say, the export set may have more methods and metadata than the base class.

Su,

* The only possible occurrence of a class interface is the loss of the interface, rather than obtaining them.

*

* If it is necessary to transform upwards, inheritance is necessary.

* An object can be used either as its own type or as its base type. This is called "upward transformation ".

"Upcasting

*

*

*
"Dynamic binding" is also called "post-binding" and "runtime binding"

* When a subclass object is created, the base class object is referenced, and the base class object is used to call the overloaded method in the subclass

, Which will be dynamically bound to the subclass.

*

*/

/**

*
<P> title: </P>

*

*
<P> Description: </P>

*(
1) Hide implementation
Hiding

* Java access permission modifier, which isProgramThe library developers should specify to the client programmer which can be used and which cannot be used.

* You usually need to consider which Members want to be disclosed to the client programmer.

* Any method you think is a class assistant, you can set it to private

*(
2)

*

*

*
Class is used to create a new data type, instead of simply creating a data and method box. Each compilation unit can only have one public
Class

*

*/