"Java programming" Object oriented OOP (i)

Object-oriented concepts:

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Object-oriented programming Oop:object oriented programming

Process-oriented Programming ooa:oriented object analyze

Object-oriented design ood:oriented

Object:

Class:

Package: Encapsulation

Inheritance: Inheritance

Polymorphic: Polymorphism

Attribute (member variable):

Behavior (member function):

Heap: Heap

Arrays and objects in the heap

Stack: Stack

Method in the Stack

Member variables:

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Member variables are defined in the class and can be accessed throughout the class.

Member variables are established with the creation of an object and exist in the heap memory where the object resides.

The member variable has a default initialization value of NULL, or you can specify a default value

Local variables:

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Local variables are defined only in local scopes, such as within functions, within statements, and so on.

Local variables exist in the stack memory.

The scope of the action ends, and the variable space is automatically freed.

Local variables do not have default initialization values.

constructor function:

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Characteristics:

The function name is the same as the class name

Do not define return value types

There is no specific return value, and the object is definitely returned after creation.

If the class does not have a constructor defined, the JVM allocates an empty construct.

If the class defines a constructor, there is no empty construct.

Role:

Initializes the object.

Attention:

The characteristics of the default constructor.

Multiple constructors exist in the form of overloading.

Code block:

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Defined:

The code uses a separate {} enclosing content.

Classification:

To construct a code block:

One of the members of the class

Use a section of code enclosed in {}

When an object is created, it is called before the constructor.

Local code block:

Code blocks defined within a method

Static code block:

Constructs a block with the static decorated code, which is called once when the class is loaded and is no longer called. The initialization process for static member variables is usually placed.

"Java programming" Object oriented OOP (i)