Protected method in Final Class

Hi all
Can we have protected method in Final class ?
If so how is it possible ?
Vicky

Final classes cannot have subclasses and hence no need of protected methods.
No comments on possibility.
Check this link from SAP help to know more :
http://help.sap.com/saphelp_nw70/helpdata/en/dd/4049c40f4611d3b9380000e8353423/content.htm
Hope this helps you.
Edited by: Harsh Bhalla on Dec 19, 2009 3:35 PM

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Protected methods in abstract classes

Hello All
I have some problem which I cannot find a workaround for.
I have three classes:
package my.one;
public abstract class First {
protected void do();
protected void now();
package my.one;
public class NotWantToHave extends First {
protected First obj;
public NotWantToHave(First O) { obj = O; }
public void do() { obj.do(); }
public void now() { obj.now(); }
package my.two;
public class Second extends my.one.First {
protected void do() { System.out.println("Second does"); }
protected void now() { System.out.println("Second does now"); }
package my.three;
public class Three extends my.one.First {
protected my.one.First obj;
public Three(my.one.First O) { obj = O; }
protected void do() { System.out.println("Doing"); }
protected void now() { obj.now(); } // Not possible, see later text
Problem is, as one can read in http://java.sun.com/docs/books/tutorial/java/javaOO/accesscontrol.html , it says that you cannot access protected members and methods from classes if they are in a different package. However, since my class Three should not concern about the method now() but should use from some other class that implements (i.e. class Second), the question I have is how to do?
One way would be to implement a class that simply make a forward call to any protected method in the same package the abstract class is in like in class NotWantToHave and pass it to the constructor of class Third while this class was created with an instance of class Second. However, such a call would look very clumsy (new my.three.Third(new my.one.NotWantToHave(new my.two.Second()));). Furthermore, everyone could create an instance of class NotWantToHave and can invoke the methods defined as protected in class First, so the access restriction would be quite useless.
Does anyone has a good idea how to do?

Hi
One way I found is to have a nested, protected static final class in my super-class First and provide a protected static final method that returns a class where all methods of the super-class are made public and thus accessible from sub-classes at will. The only requirement is that a sub-class must invoke this method to encapsulate other implementations of the super-class and never publish the wrapper class instance. This will look as follows:
package my.one;
public abstract class First {
protected final static class Wrap extends First { // extend First to make sure not to forget any abstract method
    protected First F;
    public void do() { F.do(); }
    public void now() { F.now(); }
    protected Wrap(First Obj) { F = Obj; }
} // end Wrap
protected final static First.Wrap wrap(First Obj) { return new First.Wrap(Obj); }
protected abstract void do();
protected abstract void now();
} // end First*******
package my.two;
public class Second extends my.one.First {
protected void do() { System.out.println("Second does"); }
protected void now() { System.out.println("Second does now"); }
} // end Second*******
package my.three;
public class Three extends my.one.First {
protected my.one.First.Wrap obj;
public Three(my.one.First O) { obj = my.one.First.wrap(O); }
protected void do() { System.out.println("Doing"); }
protected void now() { obj.now(); } // Not possible, see later text
} // end Third*******
In this way, I can access all methods in the abstract super class since the Wrap class makes them public while the methods are not accessible from outside the package to i.e. a GUI that uses the protocol.
However, it still looks clumsy and I would appreciate very much if someone knows a more clear solution.
And, please, do not tell me that I stand on my rope and wonder why I fall down. I hope I know what I am doing and of course, I know the specification (why else I should mention about the link to the specification and refer to it?). But I am quite sure that I am not the first person facing this problem and I hope someone out there could tell me about their solution.
My requirements are to access protected methods on sub-classes of a super-class that are not known yet (because they are developed in the far, far future ...) in other sub-classes of the same super-class without make those methods public to not inveigle their usage where they should not be used.
Thanks

How to Access Protected Method of a Class

Hi,
I need to access a Protected method (ADOPT_LAYOUT) of class CL_REIS_VIEW_DEFAULT.
If i try to call that method by using class Instance it is giving error as no access to protected class. Is there any other way to access it..

Hi,
You can create a sub-class of this class CL_REIS_VIEW_DEFAULT, add a new method which is in public section and call the method ADOPT_LAYOUT of the super-class in the new method. Now you can create an instance of the sub-class and call the new sub-class method.
REPORT ZCD_TEST.
class sub_class definition inheriting from CL_REIS_VIEW_DEFAULT.
public section.
methods: meth1 changing cs_layout type LVC_S_LAYO.
endclass.
class sub_class implementation.
method meth1.
call method ADOPT_LAYOUT changing CS_LAYOUT = cs_layout.
endmethod.
endclass.
data: cref type ref to sub_class.
data: v_layout type LVC_S_LAYO.
start-of-selection.
create object cref.
call method cref->meth1 changing cs_layout = v_layout.

Final method and final class

What is final method and final class in abap objects.

ejp wrote:
Since that doesn't work--or would overyy complex to implement... would be impossible to implement. Once the method-local copy goes out of existence, ipso facto it can never be changed. This is the whole point.I consider it impossible too, but I'm not a language/compiler/runtime expert, so I allowed for the possibility that there could be some way to do it--e.g. local variables that are references in inner classes live on the heap instead of the stack, or something. My point isn't that it's possible, just that if it were somehow to be done, it would by ugly, so we may as well consider it impossible--it just ain't gonna happen.
we go with the logic, "Okay, we need to copies, but keeping them in sync is a nightmareNo, it is +meaningless.+No, it's not meaningless. If we have the two copies, and they're not final, then after the inner object is created, the method can continue running, and either the method or the inner object could modify its copy. As far as our code knows, it's the same variable, so there'd have to be some way to keep them in sync. That's either impossible or undesirably complex--like the above, it doesn't matter which--so it's final in order to get past the issue of keeping the copies in sync.

ECATT: How to access a protected method of a class with eCATT?

Hi,
These is a class with a protected method. now i am willing to automate the scenario with eCATT. Since the method is Protected i am unable to use createobj and use callmethod. Could anyone suggest me a work around for this ?
Regards
Amit
Edited by: Amit Kumar on Jan 10, 2012 9:53 AM

Hello Anil,
You can write ABAP Code to do that inside eCATT Command.
ABAP.
ENDABAP.
Limitation of doing that is you can only use local variable inside ABAP.... ENDABAP. bracket.
Regards,
Bhavesh

How to use protected method of a class in application

Hi,
will u please tell me how to use protected method of class in application. (class:cl_gui_textcontrol, method:limit_text)
Thanks in advance,
Praba.

Hi Prabha,
You can set the maximum number of characters in a textedit control in the CREATE OBJECT statement itself.
Just see the first parameter in the method . I mean MAX_NUMBER_CHARS. Just set that value to the required number.
Eg:
data: edit type ref to CL_GUI_TEXTEDIT.
create object edit
exporting
    MAX_NUMBER_CHARS       = 10
   STYLE                  = 0
   WORDWRAP_MODE          = WORDWRAP_AT_WINDOWBORDER
   WORDWRAP_POSITION      = -1
   WORDWRAP_TO_LINEBREAK_MODE = FALSE
   FILEDROP_MODE          = DROPFILE_EVENT_OFF
    parent                 = OBJ_CUSTOM_CONTAINER
   LIFETIME               =
   NAME                   =
EXCEPTIONS
    ERROR_CNTL_CREATE      = 1
    ERROR_CNTL_INIT        = 2
    ERROR_CNTL_LINK        = 3
    ERROR_DP_CREATE        = 4
    GUI_TYPE_NOT_SUPPORTED = 5
    others                 = 6
IF sy-subrc <> 0.
MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
           WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
In this case, the max: number of characters will be set to 10.
I hope your query is solved.
Regards,
SP.

How to get protected method ?

I thought i can get protected method of my class when calling a Class.getMethod(String, Class []) in another class which inside the same package. However, it seem that i can't do that because it throw me a NoSuchMethodException when the method was protected. I thought all classes in same package can access the protected methods or fields of each other ??? Why ?
So, how i'm able to get the protected method in runtime ? (Hopefully no need to do anything with the SecurityManager)

It is working
Pls try the following program ...
public class p1 {
public static void main(String as[]) {
p2 ps2 = new p2();
ps2.abc();
class p2 {
protected void abc() {
System.out.println("Hello");
regards,
namanc

How to access a proctected method of a class

Hi All,
I have the below code where in the idents_get is a protected method of the class.so when i activate it is throwing an error, method is unkown or protected or private.
data: gv_class TYPE REF TO /tdag/cpcl_decl_sub_view_ctrl.
   create object gv_class.
    CALL METHOD gv_class->idents_get
      EXPORTING
        i_estcat       = gc_estcat6
        i_pos_wanted   = 1
      IMPORTING
        et_idents      = lt_idents
      changing
        xt_recns       = li_recn
      EXCEPTIONS
        read_failed    = 1
        others         = 2.
i know protected methods can be accessed in derived class.
I'm new to ABAP oops concepts please give me some pointers to access a protected method.
or any sample code to access protected method.
Thanks in advance,
Srilakshmi.

Hello Srilakshmi
You can access protected methods WITHIN an instance of the class or WITHIN an instance of a sub-class.
However, in your case you are calling the method from the report and, therefore, the class must be PUBLIC.
Regards
Uwe

Protected method

Hi experts
how to call a protected method .
thanks
priyank

Hi,
You can call a protected method in a class if the class is a subclass of that super class.
for that use inheritance.
class super_class definition.
protected section.
methods protected_method.
endclass.
class super_class implementation.
method protected_method.
end method.
endclass.
Class sub_class inheriting from super_class.
endclass.
Class sub_class implementation.
method protected_method. " If you are redefining
end method.
endclass.
start-of-selection.
data: ref_sub type ref to sub_class. " referenec variable
create object ref_sub. "creating instance or object
call method ref_sub->protected_method. " calling the protected method
like that
check out this link-
http://www.sapbrainsonline.com/ARTICLES/TECHNICAL/OBJECTS/objects.html
Regards,
Sujit

Inaccessible with local variable(non-final) via method local inner class

Hi All,
Usually local variables, including automatic final variable live on the stack and objects & instanace variables live on the heap.The contracts for using the method local inner class should allow merely method final variable, not non-final stack variable.
Can anyone please clarify me ,behind the scene what is actual fact why method inner class should not access the stack(method) variable and only allow final variable?
Is anything correlated with the stack and heap aspects?
Thanks,
Stalin.G

[email protected] wrote:
...behind the scene what is actual fact why method inner class should not access the stack(method) variable and only allow final variable?...explained by dcminter and Jardium in [an older thread|http://forums.sun.com/thread.jspa?messageID=10694240#10694240|http://forums.sun.com/thread.jspa?messageID=10694240#10694240]:
...Final variables are copied into inner classes - that's why they have to be declared final; to avoid the developer making an incorrect assumption that the local variable can be modified and have the change reflected in the copy.
When a local class uses a local variable, it doesn't actually use the variable. Instead, it takes a copy of the value which is contained in the variable at the moment the class is instantiated. It's like passing the variable to a constructor of the class, except that you do not actually declare any such constructor in your code.
To avoid messy execution flows to be present in a Java method, the Java language authors thought it was better to allow a single value to be present in such a variable throughout all its life. Thus, the variable has to be declared final.
...HTH

Overidding a method defined in a Final class via an interface.

Hi,
Is it possible to override methods of a final class
which has implemented methods of an interface.
interface A{
     void method1();
public final class FinalityA implements A{
     public void method1(){
          // Code
}Now,I would like to override the functionality of
method1() defined in class FinalityA.
I cannot subclass FinalityA as this class is final.
// Invalid.
class Myclass extends FinalityA{
}Is it possible to override the functionality defined in method1()
Please suggest

You can do:
public class MyClass implements A {
   private final FinalityA _wrapee;
   public MyClass(FinalityA wrapped) {
       _wrapee = wrapped;
public void method1() {
       .. do some special processing
      _wrapee.method1();
       .. do some more stuff
        }If you want to get really clever you can do stuff with java.lang.reflect.Proxy that allows you to automatically pass on calls to interface methods (this kind of thing is increasingly used for stuff like transaction management).
What you can't do is to fiddle with the code of the method if called from a reference to FinalityA rather than a reference to the interface. The whole point of final classes and methods is to prevent that.

Why method local inner class can use final variable rather than....

Hi all
Just a quick question.
Why method-local inner class can access final variable defined in method only?
I know the reason why it can not access instance variable in method.
Just can not figure out why??
any reply would be appreciated.
Steven

Local classes can most definitely reference instance variables. The reason they cannot reference non final local variables is because the local class instance can remain in memory after the method returns. When the method returns the local variables go out of scope, so a copy of them is needed. If the variables weren't final then the copy of the variable in the method could change, while the copy in the local class didn't, so they'd be out of synch.

How to use protected method of a particular class described in API

I read in some forum that for accessing protected method reflcetion should be used. If I'm not wrong then how can I use reflection to access such methods and if reflection isn't the only way then what is another alternative. Please help me...
regards,
Jay

I read in some forum that for accessing protected
method reflcetion should be used. If I'm not wrong
then how can I use reflection to access such methods
and if reflection isn't the only way then what is
another alternative. Please help me...Two ways:
- either extend that class
- or don't use it at all
If you use reflection, you're very likely to break something. And not only the design. Remember that the method is supposed to be inaccessible for outside classes.

How do I redefine a Method of a Final Class?

Hi,
Is it possible to redefine a method of a final class and if so, can someone please give me a brief example of that technique?
Thank you very much!
Andy

Hi,
Please find the example.
Program Description :      Interface I1 contains two methods : M1 and M2.
I1 is included and incorporated in class : C1 with M2 as a final method. Both the methods are implemented in class C1.
Class C2 is a subclass of class C1. It redefines method : I1M1 and re-implements it, but it does not do that for I1M2 as that is declared as final method.
In the START-OF-SELECTION block, object OREF1 is created from class C1 and OREF2 from class C2 and both the methods M1 and M2 are called using both the objects.
Example:
report ytest .
interface i1 .
methods : m1 ,
            m2 .
endinterface.
class c1 definition.
public section.
   interfaces : I1 final methods m2 .
endclass.
class c1 implementation.
method i1~m1.
   write:/5 'I am m1 in c1'.
endmethod.
method i1~m2.
   write:/5 'I am m2 in c1'.
endmethod.
endclass.
class c2 definition inheriting from c1.
public section.
   methods : i1~m1 redefinition .
endclass.
class c2 implementation.
method : i1~m1.
   write:/5 'I am m1 in c2'.
endmethod.
endclass.
start-of-selection.
data : oref1 type ref to c1,
         oref2 type ref to c2 .
   create object : oref1 , oref2.
   call method : oref1->i1~m1 , u201C Output : I am m1 in c1
                  oref2->i1~m1 , u201C Output : I am m1 in c2
                  oref1->i1~m2 , u201C Output : I am m2 in c1
                  oref2->i1~m2 . u201C Output : I am m2 in c1
Output :      I am m1 in c1
I am m1 in c2
I am m2 in c1
I am m2 in c1
Thanks,
Anitha

Invoking method of final subclass of abstract class is slow

hi,
I've diagnosed a performance regression in my code which boils down to the example at the end of the post.
Would it be possible to have the vm dynamically figure out that within the hotspot in the test method, its
safe to ditch the dynamic dispatch and skip that overhead?
I thought marking the method as final would allow the vm to peform some run-time optimisations - I'm pretty sure I've been able to measure that in different situations; marking the test method's parameter (a) as final, also doesn't help.
Rather than have an abstract class, its looking like the performance requirements will dictate some copy and paste to
help the vm along - does anyone know if I'm missing something here?
thanks in advance,
asjf
The output I see (using 6.0 update 10) is:
B foo 28
B bar 95
C foo 29
C bar 86
D foo 26
D bar 92
E foo 29
E bar 82
public class MethodCallPerfTest {
     public static void main(String[] args) {
          test(new B());
          test(new C());
          test(new D());
          test(new E());
     public static void test(A a) {
               long start= System.currentTimeMillis();
               for(int i=0; i<8000000; i++)
                    a.foo();
               System.out.println(a.getClass().getSimpleName()+" foo "+(System.currentTimeMillis() - start));
               long start= System.currentTimeMillis();
               for(int i=0; i<8000000; i++)
                    a.bar();
               System.out.println(a.getClass().getSimpleName()+" bar "+(System.currentTimeMillis() - start));
abstract class A {
     int j;
     final void foo() {j++;}
     abstract void bar();
final class B extends A {
     int k;
     void bar() {k++;}
final class C extends A {
     int l;
     final void bar() {l++;}
class D extends A {
     int m;
     final void bar() {m++;}
class E extends A {
     int n;
     void bar() {n++;}
}

is it because references to the final fields are resolved at compile-time ?
such that the compiler must know the value of USE in:if(USE){
// a
// b at compile time so it can remove either "b" or "a". I think so. hmm.

Protected method in Final Class

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