Java Reflection

Clasa de test Clasa

public class Clasa {
 private int a;
 Clasa(int val){
  a=val;
 }
 Clasa(){
  a=100;
 }
 public int getA(){
  return a;
 }
 public void setA(int val){
  a=val;
 }
 public void setA(int[] val){
  a=val[0]+val[1];
 }
 public void setA(int a,int b){
  this.a=a+b;
 }
 public void setA(String[] ab){
  a=Integer.parseInt(ab[0])+Integer.parseInt(ab[1]);
 }
}

Clasa Reflectie

import java.lang.reflect.Method;


public class Reflectie {
 public int incrementProperty(String name, Object obj) throws Exception{
     String prop = Character.toUpperCase(name.charAt(0)) +
         name.substring(1);
     String mname = "get" + prop;
            //apel get
     Class[] types = new Class[] {};
     Method method = obj.getClass().getMethod(mname, types);
     Object result = method.invoke(obj, new Object[0]);
     int value = ((Integer)result).intValue() + 1;

     //... si mult mai interesantul apel de set
     mname = "set" + prop;
     int[] p=new int[2];
     p[0]=12;
     p[1]=21;
     int abc=12;
     types = new Class[] { int.class};
     method = obj.getClass().getMethod(mname, types);
     method.invoke(obj,abc);
     return value;
 }
}

Clasa Main

public class Main {
 public static void main(String[] args) throws Exception{
  Clasa clasa=new Clasa((int)(Math.random()*100));
  Reflectie ref=new Reflectie();
  System.out.println("Inainte de reflexie: "+clasa.getA());
  ref.incrementProperty("a", clasa);
  System.out.println("Dupa reflexie: "+clasa.getA()); 
      
 }
}

Reflectia: IBM, Java Sun, Java2S
Tehnica utila in cazul inspectarii si modificarii unui obiect in timp real, in runtime.
Prin folosirea: types = new Class[] { int.class}; se specifica ce metoda ar trebui cautata, apoi se obtine metoda method = obj.getClass().getMethod(mname, types); si in final se va apela method.invoke(obj,abc);