Java notes--finalize, static, abstract, final, this keyword __java

1, the life cycle of the object (1) finalize package cn.sdut;
 public class AA {int x=100;
 
 int y=100;
  Public AA () {x=10;
 y=20;
  public AA (int x, int y) {super ();
  this.x = x;
 This.y = y;  
  @Override protected void Finalize () throws Throwable {System.out.println ("AA finalize ...");
 Super.finalize ();
 public void mm () {System.out.println (x+ "= =" +y);
  public static void Main (string[] args) {AA aa=new aa ();
  AA.MM ();
  
  ... aa=null, and the other is the same.
 System.GC ();

}//(2) static package cn.sdut;
 public class AA {static{//Static code block a program in which a static block of code executes the first System.out.println ("Static Block ...");  static int x=100;
 
 Class variable, static variable int y=100;
 Public AA () {y=20;
  public AA (int x, int y) {super ();
  this.x = x;
 This.y = y;  
  @Override protected void Finalize () throws Throwable {System.out.println ("AA finalize ...");
 Super.finalize (); public static void mm ()//class method, static method {System.out.println (x+ "=");
     public static void Main (string[] args) {AA aa=new aa ();
     System.out.println (aa.x);
     x+=20;
     AA bb=new AA ();
     System.out.println (aa.x);
     System.out.println (aa.x);
 AA.MM ();

}//2, Abstract//(1) Abstraction classes cannot be instantiated, (2) Abstract classes can define abstract methods or Non-abstract methods, and (3) classes that contain abstract methods must be abstract classes.

Package Cn.sdut;
 Public abstract class AA {static{System.out.println ("Static Block ...");
  static int x=100;
 
 int y=100;
 Public AA () {y=20;
  public AA (int x, int y) {super ();
  this.x = x;
 This.y = y;  
  @Override protected void Finalize () throws Throwable {System.out.println ("AA finalize ...");
 Super.finalize ();
 public abstract void mm ();
 
 public void mm2 () {};

public static void Main (string[] args {}} 3, final modifier variable, only 1 times assigned; Cosmetic method, subclass cannot override (overwrite) method.

Package Cn.sdut;
 public class AA {final int x;
 
 int y=100;
  Public AA () {x=20;
 y=20;
  public AA (int x, int y) {super ();
  this.x = x;
 This.y = y; Public final VOID mm2 () {};
  
 public static void Main (string[] args) {final int a=10;

} 4, this package cn.sdut;
 public class AA {final int x;
 int y=100;
 
 int z; 
  Public AA () {this (20,20);  
 z=10;
  public AA (int x, int y) {this.x = x;
 This.y = y;
 public void mm2 () {System.out.println (this.x+ "= =" +this.y);
 
 };
 public void Mm3 () {this.mm2 ();
 
 };

 public static void Main (string[] args) {}}