In-depth understanding of Java program Execution order

Look at the code first:
Class Parent {
public static String P_staticfield = "Parent class-static variable";
Public String P_field = "Parent class-variable";
What are the following? Explain the following, not very clear
static {
System.out.println (P_staticfield);
System.out.println ("Parent class-static initialization block");
}
What's this for?
{
System.out.println (P_field);
System.out.println ("Parent class-Initialization block");
}
Public Parent () {
System.out.println ("Parent class-constructor");
}
}
public class Subclass extends Parent {
public static String S_staticfield = "sub-class-Static variable";
Public String S_field = "Subclass--variable";
Static initialization blocks
static {
System.out.println (S_staticfield);
System.out.println ("Subclass-static initialization block");
}
{
System.out.println (S_field);
System.out.println ("Subclass-Initialization block");
}
Public Subclass () {
System.out.println ("Subclass--constructor");
}
public static void Main (string[] args) {
New Parent ();
System.out.println ("-------------------");
New Subclass ();
System.out.println ("-------------------");
New Subclass ();
}
}
The running result of the program is:
Parent class--Static variable
Parent class--static initialization block
Subclass--Static variables
Subclass--Static initialization block
Parent class--variable
Parent class--initialization block
Parent class--constructor
-------------------
Parent class--variable
Parent class--initialization block
Parent class--constructor
Subclass--Variables
Subclass--Initialization block
Sub-class--constructor
-------------------
Parent class--variable
Parent class--initialization block
Parent class--constructor
Subclass--Variables
Subclass--Initialization block
Sub-class--constructor

classA { PublicA () {System.out.println ("A method of construction"); }     Public Static intj =print ();  Public Static intprint () {System.out.println ("A print"); return521; }} Public classBextendsA { PublicB () {System.out.println ("B's Construction method"); }     Public Static intK =print ();  Public Static intprint () {System.out.println ("B print"); return522; }     Public Static voidMain (string[] args) {System.out.println ("Main Start"); b b=NewB (); System.out.println ("------------------------"); A A=NewB (); }}

Output:

A Print
B Print
Main start
The construction method of a
Construction method of B
------------------------
The construction method of a
Construction method of B

In-depth understanding of Java program Execution order