Summary of the execution order of static, non-static, and constructive methods in a class

Little scum · Posted on 4/6/2017 3:12:32 PM

1 /*

2 * Several principles

3 * 1. Static member variables

4 * 1. Static member variables are class variables, and all objects share the same memory space

5 * 2. The declaration and definition of static member variables is executed only once when the class is loaded for the first time

6 * 3. When loading a class for the first time, first assign initial values to all static member variables according to the type, and then attach right values to those with rvalues

7 * 2. Static initial block

8 * 1. Static initialization blocks are only executed once when the class is loaded for the first time

9       * ······ Multiple static member variables and static initiation fast reference occurrence order are executed sequentially······

10 * 3. Dynamic member variables

11 * 1. The definition of dynamic member variables is executed before the constructor each time an object is instantiated

12 * 4. Dynamic initialization block

13*1. The dynamic initialization block is executed before the constructor each time an object is instantiated

14       * ······ Multiple dynamic member variables and dynamic initialization blocks are executed in the order in which they appear······

15 * Summary: In general, when a class is loaded for the first time, it is executed in the following order, without inheritance involved

16 * 1. Execute static member variable definition and static initialization block in the order of occurrence

17 * 2. Execute dynamic member variable definition and dynamic initialization block in the order of occurrence

18 * 3. Execute the constructor

19 * When instantiating an object again, only steps 2 and 3 can be executed

20       *

21       * ············ Member variables and definitions and initialization blocks are executed before the constructor·········

22 * 5. When inheritance is involved, it shall be carried out in the following order

23 * 1. Execute the static member variable definition and static initialization block of the parent class, and execute the static member variable definition and static initialization block of the subclass

24 * 2. Execute the non-static member variable definition and dynamic initialization block of the parent class, and execute the parent class construction method

25 * 3. Execute the definition of non-static member variables of subclasses and dynamically initialize blocks, and execute the subclass construction method

26 * Also: If the method used in the parent class construction method has been rewritten by the subclass, then the subclass rewrite method is used when calling the parent class constructor when constructing the subclass object

Little scum · Posted on 4/6/2017 3:17:20 PM

When loading a class for the first time, first assign initial values to all static member variables according to the type, and then execute multiple static member variables in sequence for the attached right value with right values

[Source] Summary of the execution order of static, non-static, and constructive methods in a class

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