20165334 Java Programming 4th Week of study summary

Study number 20165334 "Java Program Design" 4th Week study summary textbook study content summary fifth main content

• Subclass and Parent class
• Inheritance of subclasses
• Subclasses and objects
• Hide and method overrides for member variables
• Super keyword
• Final keyword
• Objects on top of a transition object
• Inheritance and polymorphism
• Abstract class and abstract method
• For abstract programming

• Open-Close principle

  About the Transition object

  Use of transformed objects on
  1. On the transform object cannot manipulate the new member variables of the subclass, you cannot call the new method of the subclass.

2. On a transformed object you can access a subclass of inherited or hidden member variables, or you can call an instance method overridden by a method or subclass that inherits from a child class.

3. If the subclass overrides an instance method of the parent class, the instance method that is overridden by the subclass must be called when the instance method is invoked with the transformed object.

Sixth chapter

• Main content
• Interface
• Implementing interfaces
• Understanding Interfaces
• Interface callbacks
• Interface and polymorphism
• interface variables do parameters

• Interface-Oriented Programming

  Understanding of the interface

  (1) An interface can abstract an important standard of behavior, which is represented by an abstract method.

(2) You can assign a reference to the object of the class that implements the interface to the interface variable, which can invoke the interface method implemented by that class, that is, the specific behavior given by the class according to the standard of behavior in the interface.

The interface and the abstract class are compared as follows:

1. Abstract classes and interfaces can have an abstract method.

2. There can be only constants in an interface, no variables, and there can be constants or variables in an abstract class.

3. Abstract classes can also have non-abstract methods, interfaces are not available.

Problems in code debugging and the resolution process

The code of the textbook debugging basically belongs to some careless errors caused by errors, in accordance with the error prompts are corrected. But in this week's JDB test encountered some difficulties in this blog to do a related summary

Code Hosting

(run result of statistics.sh script)

Last week's summary of the wrong quiz

Learning progress Bar

	lines of code (new/cumulative)	Blog Volume (Add/accumulate)	Learning Time (new/cumulative)	Important Growth
Goal	5000 rows	30 Articles	400 hours
First week	100/200	2/2	20/20
Second week	300/500	2/4	18/38
Third week	800/1000	3/7	22/60
Week Four	800/1300	2/9	30/90

Resources

• Java Learning Notes (8th Edition)

• Java Learning Note (8th Edition) Learning Guide

• ...

20165334 Java Programming 4th Week of study summary