GetClass (), class attributes, and GetName () parsing (finishing)

One,

GetClass Method:
Type: public final class<? Extends Object> getclass ()
Function: Returns the Java.lang.Class object of the Run-time class of the object (interpretation on the API)
There is a method type to know that the method can only be invoked by an instance variable of the class
Example:

JButton B1 = new JButton ("Button1"); System.out.println (B1.getclass ());
Output:
Class Javax.swing.JButton

Class attribute
When you want to get a class object (as a function argument), you can't call the GetClass method, you can only use the class name. class to achieve the effect
Example:

System.out.println (Jbutton.class);

Output:
Class Javax.swing.JButton

GetName method:
Type: Public String getName ()
Function: Returns the entity name represented by the secondary class object as a string
Example:

JButton B1 = new JButton ("Button1"); System.out.println (B1.getname ());
Output:
Javax.swing.JButton

It can be found that the class attribute and the output returned by the GetClass are the same, with GetName returned with a class and a space less than the preceding two kinds.

. The Eclipse tool can press "." And then immediately prompts you for a choice.
So how does he know "." What are the ways to do it later?
The grammar he uses is GetClass (). GetMethods ();

Second,

. class is actually loaded in the Java runtime

GetClass () is dynamically loaded when the program is run

The following examples illustrate:
First build a base class baseclass      package  classyongfa;      public  class  Baseclass {      Private  String height;   public  string  getheight ()    {      return  height;  }       Public  void  setheight (string height)    {           this .height=height;       }   Following is the inheritance BaseClass class extendclass      package  classyongfa;      Public  class  extendclass extends  Baseclass {      Private  string  width;   public  string getwidth ()    {      return  width;  }      public  void  setwidth (string width)    {           this .width=width;       }    Public  static  void  main (string[] arg0)    {       Baseclass baseclass1=new  extendclass ();      baseclass baseclass2=new  baseclass ();      system.out.println (Baseclass1.getclass (). GetSimpleName ());// The actual operation is inherited class Extendclass       System.out.println (Baseclass2.getclass (). Getsimplename ()); The actual operation is BaseClass             system.out.println (baseclass.class. Getsimplename ());//Load Time class name    System.out.println (extendclass.class. Getsimplename ());//Load time class name      }      Results       extendclass   baseclass   baseclass   Extendclass

Three, four ways to get class objects Java reflection mechanism

Here is a concrete example to illustrate. This example comes from the "proficient in Hibernate 3.0 Java Database Persistence Layer Development practice" book.

First build a file under the Com.hqh.reflect Useinfojava

Package com.hqh.reflect;

public class Useinfo {

Private Integer ID;
Private String UserName;
private String password;

Public Integer getId () {
return ID;
}

public void SetId (Integer id) {
This.id = ID;
}

Public String GetUserName () {
return userName;
}

public void Setusername (String userName) {
This.username = UserName;
}

Public String GetPassword () {
return password;
}

public void SetPassword (String password) {
This.password = password;
}

}

Package com.hqh.reflect;

public class Getclasstest {

public static void Main (string[] args) {
Getclasstest test = new Getclasstest ();
if (test. Classcheck ())
System.out.println ("OK");

}

public Boolean Classcheck () {
try {
SYSTEM.OUT.PRINTLN ("Obtaining objects through the class itself");
Class userclass = This.getclass ();
System.out.println (Userclass.getname ());
System.out.println ("===========");

System.out.println ("Get the parent class object from an instance of a subclass");
Useinfo useinfo = new Useinfo ();
UserClass = Useinfo.getclass ();
System.out.println (Userclass.getname ());
Class Subuserclass = Userclass.getsuperclass ();
System.out.println (Subuserclass.getname ());
System.out.println ("===========");

System.out.println ("Get Objects by class name. Class");
Class forclass = Com.hqh.reflect.UseInfo.class;
System.out.println (Forclass.getname ());
System.out.println ("===========");

SYSTEM.OUT.PRINTLN ("Fetch object by string of class name");
Class forname = Class.forName ("Com.hqh.reflect.UseInfo");
System.out.println (Forname.getname ());
System.out.println ("=============");

catch (Exception e) {
E.printstacktrace ();
return false;
}
return true;
}
}

Results:

Get objects from the class itself
Com.hqh.reflect.GetClassTest
===========
Gets the parent class object from an instance of a subclass
Com.hqh.reflect.UseInfo
Java.lang.Object
===========
Gets the object
Com.hqh.reflect.UseInfo
===========
through a string of class names.
Com.hqh.reflect.UseInfo
=============
OK