Ask the problem of subclass initialization

dior315

When the child class is instantiated, the parent class and child class are loaded, the variables of the parent class and the child class are initialized, and the constructor methods of the parent class and the child class are called, so that a parent class is instantiated? Then the instantiation ends, the parent object becomes garbage?
I'm not sure, you guys have helped a lot. Thank you.

nanase

This parent class does not have any specific references, it should be garbage.

lz look at this code again

class X
{
    Y b = new Y ();

    X ()
    {
System.out.println ("X");
    }
}

class Y
{
    Y ()
    {
System.out.println ("Y");
    }
}

public class Test extends X
{
    Y y = new Y ();

    Test ()
    {
System.out.println ("Z");
    }

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

dior315

Read some previous related articles. Now I understand, haha.
I summarized it:
1. Loading, static initialization. Starting from main (), the loader is started. It searches for the keyword "extends" and loads the relevant classes from bottom to top. Then start static initialization from the root base class.
2.Continue to main ().
3.Instance variables (instance variables) are always initialized before the constructor. If the object is instantiated in main (), then the instance variable is initialized from the root base class and the constructor is executed. Finally, initialize the instance variable to the class where main () is located and execute the constructor.
4.Continue to main ().