Java class loading sequence and java Loading Sequence

Java class loading sequence and java Loading Sequence

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First, write the code to verify the result.
Test code:

public class Test {    public static void main(String[] args) {        new Test2();    }}

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Subclass code:

Public class Test2 extends Test3 {System. out. println ("subclass code block");} private String address = getAddress (); static {System. out. println ("subclass static code block");} private static String name = get1Name (); public Test2 () {System. out. println ("subclass constructor");} private String getAddress () {System. out. println ("subclass member variable"); return null;} private static String get1Name () {System. out. println ("subclass static variable"); return null ;}}

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Parent code:

Public class Test3 {private static String name = getName (); private String address = getAddress (); static {System. out. println ("parent static code block");} {System. out. println ("parent code block");} public Test3 () {System. out. println ("parent constructor");} private String getAddress () {System. out. println ("parent class member variable"); return null;} private static String getName () {System. out. println ("parent static variable"); return null ;}}

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The above code can check the order of class loading.

Run the code. The console prints the result as follows:

With a parent category. PNG
No parent category. PNG

It is found that the loading sequence of variables and code blocks is related to the order in the code.

Summary:
If no parent class exists, the loading sequence is:
Static member variables, static code blocks --- member variables, code blocks ---- constructor.

When a parent class exists, the loading sequence is:
Static member variables of the parent class, static code blocks of the parent class --- static member variables of the Child class, static code blocks of the Child class ----- parent member variables and parent code blocks
---- Parent class constructor ----- Child class member variable, Child class code block ---- Child class constructor.