java - Create Fields and methods dynamically -

i want add new fields(variables) , encapsulating methods given class. example: class name student has no fields below:

public class student implements serializable{  } 

then in application instance created;

student s=new student(); 

i want add new methods not exist student class @ run time.for example: want add field called studentname, , getstudentname() , setstudentname() methods.

then @ run time student object this;

public class student implements serializable{      private string studentname;      public void setstudentname(..){}     public string getstudnetname(){return ...;} } 

in application objects written text file , objects of same type not have variables. therefore, want add required fields save memory.

any way there way this? sample code or link?

edit: or else can create class either , create instances not exists ?

edit 2: of answered , got many info , ideas. , changed way better path suggestions well

why not create hashmap of values? more efficient, , has flexibility you're looking for.

public class student {       private hashmap<string, string> values;        public student()       {           this.values = new hashmap<string, string>();       }        public void addvalue(string name, string value)       {           values.put(name, value);       }        public string getvalue(string name)       {           return values.get(name);       } } 

why hashmap?

you said objects may have differing values, , you'll defining new methods , attributes string. well.. achieve functionality without horrible bytecode manipulation. example:

string attrname = "name"; string attrvalue = "jim"; student stu = new student(); stu.addvalue(attrname, attrvalue); 

at moment, you've got 1 value in hashmap. overheard have face hashmap object itself, , 2 methods, frankly fair trade off far tidier solution.