Java Reflection Basics Application Notes

The reflection mechanism is widely used. Here's a simple note under

 PackageCom.shone.ailin;ImportJava.lang.reflect.Constructor;ImportJava.lang.reflect.Field;Importjava.lang.reflect.InvocationTargetException;ImportJava.lang.reflect.Method; Public classReflectdemo { Public Static voidMain (string[] args)throwsException {printvar ();        CreateInstance ();            Printallvarname (); }        //Print all member variable names    Private Static voidPrintallvarname () {//TODO auto-generated Method StubPoint P =NewPoint (1,3); Field[] Fields=P.getclass (). Getdeclaredfields ();  for(inti=0;i<fields.length;i++) {System.out.println ("var[" +i+ "]=" +fields[i].getname ()); }            }    //Print the value of a member variable    Private Static voidPrintvar ()throwsnosuchfieldexception, SecurityException, IllegalArgumentException, illegalaccessexception {point P=NewPoint (1,4); Field FX= P.getclass (). Getdeclaredfield ("x"); Fx.setaccessible (true);//it has to be added here. Otherwise, an exception will be thrown. Because it is a private member variable, it requires a violent reflection        intx = (int) Fx.get (p); System.out.println ("X=" +x); }    //To create an instantiated object and invoke a method    Private Static voidCreateInstance ()throwsException, SecurityException {Constructor<Point> con = point.class. GetConstructor (int.class,int.class); Try{Point instance= Con.newinstance (1,3); Method m= Instance.getclass (). Getdeclaredmethod ("Addcount",int.class,int.class); M.setaccessible (true); Try {                intCount = (int) M.invoke (instance,2,7);                            System.out.println (count); } Catch(illegalaccessexception e) {e.printstacktrace (); } Catch(IllegalArgumentException e) {e.printstacktrace (); } Catch(InvocationTargetException e) {e.printstacktrace (); }                                } Catch(nosuchmethodexception e) {e.printstacktrace (); } Catch(SecurityException e) {e.printstacktrace (); }    }    }

Point class

 PackageCom.shone.ailin; Public classPoint {Private intx;  Public inty;  PublicPoint (intXinty) {//TODO auto-generated Constructor stub        Super();  This. x =x;  This. y =y; }        Private intAddcount (intXinty) {returnx+y; }}

Java Reflection Basics Application Notes