class  BaseHandler {
       private  String name;
      BaseHander(String name){  this .name = name;}
       public  String getName(){ return  name};
      
       abstract   void  handle();

       private   static  HashMap<String, BaseHandler> map =  new  HashMap<String, BaseHandler>();
       public   final   static   void  registerHandler(BaseHandler handler) {
             map.put(handler.getName(), handler);
      } 

       public   final   static  BaseHandler getHandler(String name){
             return  map.get(name); //todo: учесть ситуацию, когда не существует обработчика для name 
      }
}


 class  XXXHandler  extends  BaseHandler {
       void  handle() {
            System.out.println("Preved");
      }
}

//Инициализация. В принципе можно разместить в статическом блоке класса BaseHandler
BaseHandler.registerHandler( new  XXXHandler());
...

//usage       
String s = ...;
BaseHandler.getHandler(s).handle();
      

String s = ...;
BaseHandler.getHandler(s).handle( new  Context(....));

 class  XXXHandler  extends  BaseHandler {
      XXXHadler() { super ("xxx")}
       void  handle() {
            System.out.println("Preved");
      }
}

 import  java.lang.reflect.Method;
 import  java.lang.reflect.InvocationTargetException;

 public   class  Test {

    //1.4
     public   static   void  main(String[] arg)  throws  NoSuchMethodException, IllegalAccessException, InvocationTargetException {

        Test test =  new  Test();

        Method methodA = test.getClass().getDeclaredMethod("doA",  new   Class []{ int . class , String. class ,  float . class });
        methodA.invoke(test,  new  Object[]{ new  Integer( 1 ), "Petya",  new   Float ( 3 . 5 )});

        Method methodB = test.getClass().getDeclaredMethod("doB",  new   Class []{ int . class , String. class ,  Float . class });
        methodB.invoke(test,  new  Object[]{ new  Integer( 1 ), "Petya",  new   Float ( 3 . 5 )});

    }

    //1.5
     public   static   void  main(String[] arg)  throws  NoSuchMethodException, IllegalAccessException, InvocationTargetException {

        Test test =  new  Test();

        Method methodA = test.getClass().getDeclaredMethod("doA",  int . class , String. class ,  float . class );
        methodA.invoke(test,  1 , "Petya",  3 .5f);

        Method methodB = test.getClass().getDeclaredMethod("doB",  int . class , String. class ,  Float . class );
        methodB.invoke(test,  1 , "Petya",  3 .5f);

    }

     void  doA( int  a, String b,  float  c) {
        System.out.println("doA:" + a + " " + b + " " + c);
    }

     void  doB( int  a, String b,  Float  c) {
        System.out.println("doB:" + a + " " + b + " " + c);
    }
}

catch (InvocationTargetException e) {

    if (e.getCause() != null) {

        throw e.getTargetException();

    }

}