Sample applets that use reflection in Java to analyze classes

ImportJava.util.*;Importjava.lang.reflect.*;/*** This program uses reflection to print all features of a class. *@version1.1 2004-02-21 *@authorCay Horstmann*/ Public classreflectiontest{ Public Static voidMain (string[] args) {//read class name from command line args or user inputString name; if(Args.length > 0) name = Args[0]; Else{Scanner in=NewScanner (system.in); System.out.println ("Enter class name (e.g. java.util.Date):"); Name=In.next (); }      Try      {         //Print class name and superclass name (if! = Object)Class cl = class.forname (name);//to get the class object from a stringClass SUPERCL =Cl.getsuperclass (); //cl.getmodifiers () returns an integer value, using different bit switches to describe the usage of modifiers like public//The modifier.tostring method returns a string that describes the bit switch. A string that converts an integer value to the corresponding modifierString modifiers =modifier.tostring (Cl.getmodifiers ()); if(Modifiers.length () > 0) System.out.print (modifiers + ""); System.out.print ("Class" +name); if(SUPERCL! =NULL&& SUPERCL! = Object.class) System.out.print ("extends" +supercl.getname ()); System.out.print ("\n{\n");         Printconstructors (CL);         System.out.println ();         Printmethods (CL);         System.out.println ();         Printfields (CL); System.out.println ("}"); }      Catch(ClassNotFoundException e) {e.printstacktrace (); } system.exit (0); }   /*** Prints All constructors of a class *@paramcl A class*/    Public Static voidprintconstructors (Class cl) {//with the class object, you get an array containing the constructor object , which contains the class description//information for all constructors of the classConstructor[] Constructors =cl.getdeclaredconstructors (); //extracting information from a constructor       for(Constructor c:constructors) {String name=C.getname (); System.out.print ("   "); String modifiers=modifier.tostring (C.getmodifiers ()); if(Modifiers.length () > 0) System.out.print (modifiers + ""); System.out.print (Name+ "("); //Print parameter Types//returns an array of class objects that describe the type of the parameterclass[] Paramtypes =c.getparametertypes ();  for(intj = 0; J < Paramtypes.length; J + +)         {            if(J > 0) System.out.print (",");         System.out.print (Paramtypes[j].getname ()); } System.out.println (");"); }   }   /*** Prints All methods of a class *@paramcl A class*/    Public Static voidPrintmethods (Class cl) {//returns an array containing the method object, returning all methods of the class or interface, but not including methods inherited by the superclassMethod[] Methods =Cl.getdeclaredmethods ();  for(Method m:methods) {//returns a class object that describes the return typeClass RetType =M.getreturntype (); String name=M.getname (); System.out.print ("   "); //print modifiers, return type and method nameString modifiers =modifier.tostring (M.getmodifiers ()); if(Modifiers.length () > 0) System.out.print (modifiers + ""); System.out.print (Rettype.getname ()+ "+ name +" ("); //Print parameter Types//returns an array of class objects that describe the type of the parameterclass[] Paramtypes =m.getparametertypes ();  for(intj = 0; J < Paramtypes.length; J + +)         {            if(J > 0) System.out.print (",");         System.out.print (Paramtypes[j].getname ()); } System.out.println (");"); }   }   /*** Prints All fields of a class *@paramcl A class*/    Public Static voidPrintfields (Class cl) {//returns an array containing Field objects that record all the fields of this classfield[] Fields =Cl.getdeclaredfields ();  for(Field f:fields) {Class type=F.gettype (); String name=F.getname (); System.out.print ("   "); String modifiers=modifier.tostring (F.getmodifiers ()); if(Modifiers.length () > 0) System.out.print (modifiers + ""); System.out.println (Type.getname ()+ "+ name +"; "); }   }}

Sample applets that use reflection in Java to analyze classes