Summary of Java programming ideas and methods

I always felt that the book was too wordy. After reading the summary, it would be easier to recall later. I wanted to be lazy and look for other people's summaries online, but I couldn't find a good one, so I had to do my best to summarize it as best as possible.

Introduction to Objects

I feel like this after seeing Introduction to Objects This book

Contents:

1.1 Abstraction process
1.2 Each object There is an interface
1.3 Each object provides services
1.4 Hidden concrete implementation
1.5 Reusing concrete implementation
1.6 Inheritance
1.7 Interchangeable objects with polymorphism
1.8 Single root inheritance structure
1.9 Container
1.10 Creation and lifetime of objects
1.11 Exception handling: handling errors
1.12 Concurrent programming
1.13 Java and the Internet
1.14 Summary

I feel like I will finally become proficient in Java after reading this. However, this chapter only introduces the basic concepts of OOP including an overview of development methods, and understands the importance of objects.

1.1 Abstraction process

Explain the orientation through the shortcomings of other languages Object language is good.

Assembly language is a slight abstraction of the underlying machine. Imperative languages ​​(such as C and BASIC) are an abstraction of assembly language. Assembly language directly controls the computer's hardware. Imperative languages Languages ​​are based on computer structures to solve problems. OOP languages ​​solve problems based on the structure of the problem and are not restricted to any specific type of problem.

1.2 Each object has an interface

Interface: determines what can be issued to a specific object Request Object: Type name

Looking at the text description, it has risen to a philosophical issue. It is easy to understand from the following example.

Light lt = new Light(); //对象lt.on;//接口向对象发出请求

1.3 Each object provides services

Benefits: 1. Helps improve the cohesion of software 2. Each object can complete a task well, but it does not try to do more things.

Understanding: Design a music player that has lyrics display, playback, pause, and background display (service). At this time, don’t just provide an object (it doesn’t try to do more Things), can provide three objects to complete three services, and three objects provide three services to complete a music player (Cohesion).

1.4 Hidden specific implementation

Download a framework from Github, my goal is to achieve For rapid application development, the framework only needs to provide me with method calls, and hiding the others will not affect my calls.

1.5 Specific implementation of reuse

• Inheritance----is the relationship of a Lychee is a fruit

• combination- ---Has a relationship There is a way to sleep on your stomach

Derive a subclass from the parent class. The subclass can absorb the data attributes and behaviors of the parent class, and can expand new capabilities.

class Shape{ 
  draw();
  erase();
  move();
  getColor();
  setColor();
}

void doSomething(Shape shape){
shape.erase();//...shape.draw();
}

Circle circle = new Circle(); //父类为ShapeTriangle triangle = new Triangle();  //父类为ShapeLine line = new Triangle();  //父类为ShapedoSomething(circle);
doSomething(triangle);
doSomething(line);

public class JianCheng extends Object {  
}

public class JianCheng {  public static void main(String[] args) {  
        JianCheng jiancheng= new JianCheng();  
        System.out.println(JianCheng instanceof Object);  
    }  
}

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