Protected Methods in Interfaces
Why don't interfaces allow you to declare protected methods? Is there a way around this?
The reason I ask involves a current project of mine. I have an inheritance hierarchy including an abstract Event base class with many concrete derived Events. I want to define many protected methods in the base Event class, which all my derived Events will use, in order to save me a lot of coding. I'm also trying to make my program reusable, and isolate the protocol changes to this Event hierarchy and a Packet hierarchy as well. For both these hierarchies, I want to implement interfaces that make sure that the programmer defines these necessary, protected methods. Yet I cannot declare protected methods in my interfaces!
> I have this same desire: to have protected
methods within interfaces.
Interfaces are not intended to (nor can they) provide
implementation.Yes, this is clear. Yet they "promise" an implementation. In the Java interface model, they only promise the public interface. I have yet to see why they cannot promise protected methods. I'm not really interested in code inheritance (reusing the code). I'm interested in what is called interface inheritance to achieve certain polymorphic goals.
>
> any design patterns that can be used to get
around this problem.
I'd suggest using composition rather than
inheritance. Let me know if I should explain
further.
Yes, I understand about composition (or delegation) as a way to "inherit" the functionality; however, I want to treat the subclasses polymorphically. I'm designing class library/frameworks that require a certain level of structure. The subclasses need to maintain the encapsulation provided by protected methods. I don't want external clients calling the protected methods, but the only way to achieve multiple (interface) inheritance is through Java's public interfaces, which then exposes the methods. I see no way around this problem. I'm not familar with the technical challenges of implementing multiple inheritance within compilers etc. At first glance, I don't see why allowing methods to be declared protected within the Java interface construct would cause serious technical problems.
~
P.S. Yes, this is an old thread...
Sorry, yes this is an old thread. I did some searching on this topic and this thread came up. Thanks for your reply.
Similar Messages
-
Why only public methods in interfaces?
Howdy all,
I'm wondering if someone can shed some light on why Java doesn't allow interfaces to declare non-public methods.
Ideally, I'd like to do something like this:
public Interface Foo {
protected void setFooProperty(int);
public int getFooProperty();
public Interface Goo {
protected void makeGooey(boolean);
public boolean isGooey();
public class A implements Foo
public class B implements Goo
public class C implements Foo, GooI don't see any technical reason why interfaces must be restricted to declaring public methods only, but it seems too arbitrary to have been done without reason. Any ideas?I don't think that is a good idea to put non-public methods in public interfaces. But I beleive that's a good idea to have protected (or friendly) interfaces to be used only in package scope. It could help a lot some projets defining a second level of data exposure of an object so that developers of that package could have more information that others users from outside the package have that are interesting to develop better algorithm that work with that data. In this way, we can defien thre levels of that access: The lower is the package user, that can see the minimum that's possible, above him we have the package developer that don't work directly with the data, but needs some deep access to it to do cool stuff, and finally we have the guy that is doing the object that deals directly with the data (and encapsulate it).
In this way we can decouple a little the data from the algorithms that work on it, put between them an interface that standarize the access to the data in an intermediate level.
Hope you are able to understand what I wrote (my english isn't so good!).
RGB -
ALV - access to protected method
Hello,
I have a object from class "CL_GUI_ALV_GRID" and want to change the protected attribute "EVT_DELAYED_CHANGE_SELECTION Constant Protected" with the method
CALL METHOD alv_grid->SET_DELAY_CHANGE_SELECTION
EXPORTING
time = lv_delay.
How can I access this protected attribute?
Thanks in advance,
HolgerThis will do what you want
Trick is to define a sub class inheriting the super class where the protected attributes and methods exist in - then you can access the protected methods and attributes.
If you do this don't forget to call the SUPER CONSTRUCTOR (of the class you are inheriting from) in your constructor method. Code example shown below.
Here I want the original and modified table of an alv grid but you can adapt this code to whatever you need.
Hope it helps.
create blank screen (100) with a custom container CCONTAINER1 and the following scren logic in it
PROCESS BEFORE OUTPUT.
MODULE STATUS_0100.
PROCESS AFTER INPUT.
MODULE USER_COMMAND_0100.
now look at the code here. Note text in Bold
PROGRAM zdynfieldcat.
class zcltest definition deferred. "For field symbol reference.
Simple test of dynamic ITAB with user defined (not ddic) fields
Build dynamic fcat
Table structure obtained via new RTTI functionality
use ALV grid to display and edit.
Create a blank screen 100 with a custom container called CCONTAINER1.
James Hawthorne
Define field symbols as these can't be defined in classes
field-symbols: <dyn_table> type standard table,
<g2> type ref to zcltest,
<g1> type ref to cl_gui_custom_container,
<actual_tab> type standard table,
<outtab> type table,
<fs1> type ANY,
<FS2> TYPE TABLE,
<fs3> type table,
<fs4> type table,
<fs5> type table.
<b>class zcltest definition inheriting from cl_gui_alv_grid.
define this as a subclass so we can access the protected attributes
of the superclass cl_gui_alv_grid</b>
public section.
types: g4 type ref to cl_gui_custom_container.
types: g3 type ref to cl_alv_changed_data_protocol.
data: i_parent type g4,
lr_rtti_struc TYPE REF TO cl_abap_structdescr, "RTTI
zog like line of lr_rtti_struc->components. "RTTI
types: struc like zog.
types: struc1 type table of struc.
methods:
constructor
importing i_parent type g4,
disp_tab
importing p_er_data_changed type g3,
create_dynamic_fcat
importing zogt type struc1
exporting it_fldcat type lvc_t_fcat.
Protected section.
data: stab type ref to data,
wa_it_fldcat type lvc_s_fcat,
c_index type sy-index.
endclass.
<b>class zcltest implementation.
METHOD constructor.
CALL METHOD super->constructor
EXPORTING
i_appl_events = 'X'
i_parent = i_parent.
endmethod
method disp_tab.
*mt_outtab is the data table held as a protected attribute
in class cl_gui_alv_grid.
assign me->mt_outtab->* TO <outtab>. "Original data
assign p_er_data_changed->mp_mod_rows TO <FS1>.
stab = p_er_data_changed->mp_mod_rows.
assign p_er_data_changed->mt_inserted_rows to <fs3>.
assign p_er_data_changed->mt_deleted_rows to <fs4>.
assign p_er_data_changed->mt_mod_cells to <fs5>.
assign stab->* TO <fs2>.
do whatever you want with <outtab>
contains data BEFORE changes each time.
Note that NEW (Changed) table has been obtained already by
call to form check_data USING P_ER_DATA_CHANGED
TYPE REF TO CL_ALV_CHANGED_DATA_PROTOCOL.
Entered data is in table defined by <fs2>
In this method you can compare original and changed data.
Easier than messing around with individual cells.
do what you want with data in <fs2> validate / update / merge etc
endmethod.</b>
method create_dynamic_fcat.
loop at zogt into zog.
c_index = c_index + 1.
clear wa_it_fldcat.
wa_it_fldcat-fieldname = zog-name .
wa_it_fldcat-datatype = zog-type_kind.
wa_it_fldcat-inttype = zog-type_kind.
wa_it_fldcat-intlen = zog-length.
wa_it_fldcat-decimals = zog-decimals.
wa_it_fldcat-coltext = zog-name.
wa_it_fldcat-lowercase = 'X'.
if c_index eq 2.
wa_it_fldcat-emphasize = 'C411'.
endif.
if c_index eq 3.
wa_it_fldcat-emphasize = 'C511'.
endif.
append wa_it_fldcat to it_fldcat .
endloop.
endmethod. "create_dynamic_fcat
endclass. "zcltest IMPLEMENTATION
class lcl_grid_event_receiver definition.
public section.
methods:
handle_data_changed
for event data_changed of zcltest
for event data_changed of cl_gui_alv_grid
importing er_data_changed,
toolbar
for event toolbar of zcltest
importing e_object
e_interactive,
user_command
for event user_command of zcltest
importing e_ucomm.
endclass.
class lcl_grid_event_receiver implementation.
method handle_data_changed.
code whatever required after data entry.
various possibilites here as you can get back Cell(s) changed
columns or the entire updated table.
Data validation is also possible here.
call method <g2>->disp_tab
EXPORTING
p_er_data_changed = er_data_changed.
endmethod. "handle_data_changed
method toolbar.
data : ls_toolbar type stb_button.
clear ls_toolbar.
move 0 to ls_toolbar-butn_type.
move 'EDIT' to ls_toolbar-function.
move space to ls_toolbar-disabled.
move 'Edit' to ls_toolbar-text.
move icon_change_text to ls_toolbar-icon.
move 'Click2Edit' to ls_toolbar-quickinfo.
append ls_toolbar to e_object->mt_toolbar.
clear ls_toolbar.
move 0 to ls_toolbar-butn_type.
move 'UPDA' to ls_toolbar-function.
move space to ls_toolbar-disabled.
move 'Update' to ls_toolbar-text.
move icon_system_save to ls_toolbar-icon.
move 'Click2Update' to ls_toolbar-quickinfo.
append ls_toolbar to e_object->mt_toolbar.
clear ls_toolbar.
move 0 to ls_toolbar-butn_type.
move 'EXIT' to ls_toolbar-function.
move space to ls_toolbar-disabled.
move 'Exit' to ls_toolbar-text.
move icon_system_end to ls_toolbar-icon.
move 'Click2Exit' to ls_toolbar-quickinfo.
append ls_toolbar to e_object->mt_toolbar.
endmethod. "toolbar
method user_command.
case e_ucomm .
when 'EDIT'. "From Tool bar
perform set_input.
perform init_grid.
when 'UPDA'. "From Tool bar
perform refresh_disp.
perform update_table.
when 'EXIT'. "From Tool bar
leave program.
endcase.
endmethod. "user_command
endclass. "lcl_grid_event_receiver IMPLEMENTATION
program data
include <icon>.
define any old internal structure NOT in DDIC
types: begin of s_elements,
anyfield1(20) type c,
anyfield2(20) type c,
anyfield3(20) type c,
anyfield4(20) type c,
anyfield5(11) type n,
end of s_elements.
data: wa_element type s_elements,
wa_data type s_elements.
Note new RTTI functionality allows field detail retrieval
at runtime for dynamic tables.
data:
grid1 type ref to zcltest,
grid_handler type ref to lcl_grid_event_receiver,
c_dec2 type s_elements-anyfield5,
wa_it_fldcat type lvc_s_fcat,
it_fldcat type lvc_t_fcat,
lr_rtti_struc TYPE REF TO cl_abap_structdescr, "RTTI
lt_comp TYPE cl_abap_structdescr=>component_table,"RTTI
ls_comp LIKE LINE OF lt_comp, "RTTI
zog like line of lr_rtti_struc->components, "RTTI
struct_grid_lset type lvc_s_layo,
l_valid type c,
new_table type ref to data.
types: struc like zog.
data: zogt type table of struc,
grid_container1 type ref to cl_gui_custom_container,
g_event_receiver type ref to lcl_grid_event_receiver,
ok_code like sy-ucomm,
i4 type int4.
start-of-selection.
call screen 100.
module status_0100 output.
if grid_container1 is initial.
create object grid_container1
exporting
container_name = 'CCONTAINER1'.
assign grid_container1 to <g1>.
create object grid1
exporting i_parent = grid_container1.
we need reference to this instance so we can use
Methods etc of zcltest class and alv (superclass)
in our event receiver class.
assign grid1 to <g2>.
create object grid_handler.
set handler:
grid_handler->user_command for grid1,
grid_handler->toolbar for grid1,
grid_handler->handle_data_changed for grid1.
Get the Internal table structure
lr_rtti_struc ?= cl_abap_structdescr=>describe_by_data( wa_data ).
Build field catalog just use basic data here
colour specific columns as well
zogt[] = lr_rtti_struc->components.
call method grid1->create_dynamic_fcat
EXPORTING
zogt = zogt
IMPORTING
it_fldcat = it_fldcat.
Create dynamic internal table and assign to field symbol.
Use dynamic field catalog just built.
call method cl_alv_table_create=>create_dynamic_table
EXPORTING
it_fieldcatalog = it_fldcat
IMPORTING
ep_table = new_table.
assign new_table->* to <dyn_table>.
perform populate_dynamic_itab.
perform init_grid.
perform register_enter_event.
set off ready for input initially
i4 = 0.
call method grid1->set_ready_for_input
EXPORTING
i_ready_for_input = i4.
endif.
endmodule. "status_0100 OUTPUT
module user_command_0100 input.
*PAI not needed in OO ALV anymore as User Commands are handled as events
*in method user_command.
*we can also get control if the Data entered and the ENTER is pressed by
*raising an event.
Control then returns to method handle_data_changed.
endmodule. "user_command_0100 INPUT
form populate_dynamic_itab.
load up a line of the dynamic table
c_dec2 = c_dec2 + 11.
wa_element-anyfield1 = 'Tabbies'.
wa_element-anyfield2 = 'ger.shepards'.
wa_element-anyfield3 = 'White mice'.
wa_element-anyfield4 = 'Any old text'.
wa_element-anyfield5 = c_dec2.
append wa_element to <dyn_table>.
endform. "populate_dynamic_itab
form exit_program.
call method grid_container1->free.
call method cl_gui_cfw=>flush.
leave program.
endform. "exit_program
form refresh_disp.
call method grid1->refresh_table_display.
endform. "refresh_disp
form update_table.
The dynamic table here is the changed table read from the grid
after user has changed it
Data can be saved to DB or whatever.
loop at <dyn_table> into wa_element.
do what you want with the data here
endloop.
switch off edit mode again for next function
i4 = 0.
call method grid1->set_ready_for_input
EXPORTING
i_ready_for_input = i4.
endform. "update_table
form set_input.
i4 = 1.
call method grid1->set_ready_for_input
EXPORTING
i_ready_for_input = i4.
endform. "set_input
form switch_input.
if i4 = 1.
i4 = 0.
else.
i4 = 1.
endif.
call method grid1->set_ready_for_input
EXPORTING
i_ready_for_input = i4.
endform. "switch_input
form init_grid.
Enabling the grid to edit mode,
struct_grid_lset-edit = 'X'. "To enable editing in ALV
struct_grid_lset-grid_title = 'Jimbos Test'.
call method grid1->set_table_for_first_display
EXPORTING
is_layout = struct_grid_lset
CHANGING
it_outtab = <dyn_table>
it_fieldcatalog = it_fldcat.
endform. "init_grid
form register_enter_event.
call method grid1->register_edit_event
EXPORTING
i_event_id = cl_gui_alv_grid=>mc_evt_enter.
Instantiate the event or it won't work.
create object g_event_receiver.
set handler g_event_receiver->handle_data_changed for grid1.
endform. "register_enter_event -
How to use protected method in jsp code
Could anyone tell me how to use protected method in jsp code ...
I declare a Calendar class , and I want to use the isTimeSet method ,
But if I write the code as follows ..
========================================================
<%
Calendar create_date = Calendar.getInstance();
if (create_date.isTimeSet) System.out.println("true");
%>
============================================================
when I run this jsp , it appears the error wirtten "isTimeSet has protected access in java.util.Calendar"The only way to access a protected variable is to subclass.
MyCalendar extends Calendar
but I doubt you need to do this. If you only want to tell if a Calendar object has a time associated with it, try using
cal.isSet( Calendar.HOUR ); -
How to create a method in Interface Controller
Hi Guys,
I am working with webdynpro ABAP sample application "Component usage" . There i got a issue like i am not able to create a method in Interface controller. There i am not able to edit anything. Can anybody please let me know how to do that.
Thanks In Advance
Regards
RavikumarHi Ravi,
Check This
If one Web Dynpro component (parent component) needs access to another Web
Dynpro component (child component) the parent component can declare the use
of the child component. A specific component usage instance is then created and
the parent component accesses the functionality of the child component via its
component interface controller.
The only parts of a Web Dynpro component that are visible to the user, are the
interface controller and the interface view(s).
All Web Dynpro components have only one interface controller. Via the
interface controller, data, methods, and event handlers can be exposed to
other components.
Interface views represent the visual interface of a Web Dynpro component.
There is a one-to-one relationship between a Window and an interface view.
Each time a window is defined, a related interface view is automatically
generated, which makes the window accessible from outside the component.
The interface view only exposes those inbound and outbound plugs to the
component user that have the interface property checked. Methods and
context data of the window are not accessible via the related interface view.
If the component has no views, there is no need to have Windows. In this
case, the component will not implement an interface view. Such components
having no visual interface are known as faceless components.
Regards
Sarath -
Not sure how to use protected method in arraylisy
Hi,
Im wondering how to use the removeRange method in java arraylist, its a protected method which returns void.
http://java.sun.com/j2se/1.3/docs/api/java/util/ArrayList.html#removeRange(int,%20int)
So if my class extends Arraylist i should be able to call the method but the compiler states that it still has protected access in arraylist. Does this mean im still overriding the method in arraylist ? A little explanation of whats happeneing would be appreciated as much as an answer
thanksIn this codefinal class myClass extends java.util.ArrayList {
private ArrayList array = new ArrayList();
public myClass(ArrayList ary){
for(int i=0;i<7;i++) {
array.add(ary.get(i));
ary.removeRange(0,7)
}You are defining a class called myClass which extends ArrayList.
You have a member variable called array which is an ArrayList
You have a constructor which takes a parameter called ary which is an ArrayList
Since ary is an ArrayList, you cannot call it's removeRange() method unless myClass is in the java.util package. Do not put your class in the java.util package.
It seems like what you want to do is to move the items in one ArrayList to another ArrayList rather than copying them. I wrote a program to do this. Here it isimport java.util.*;
public class Test3 {
public static void main(String[] args) {
MyClass myClass = new MyClass();
for (int i=0; i<5; i++) myClass.add("Item-"+i);
System.out.println("------ myClass loaded -------");
for (int i=0; i<myClass.size(); i++) System.out.println(myClass.get(i));
MyClass newClass = new MyClass(myClass);
System.out.println("------ newClass created -------");
for (int i=0; i<newClass.size(); i++) System.out.println(newClass.get(i));
System.out.println("------ myClass now contains -------");
for (int i=0; i<myClass.size(); i++) System.out.println(myClass.get(i));
class MyClass extends java.util.ArrayList {
public MyClass() {}
public MyClass(MyClass ary){
for(int i=0;i<ary.size();i++) add(ary.get(i));
ary.removeRange(0,ary.size());
}You should notice now that I don't create an ArrayList anywhere. Everything is a MyClass. By the way, class names are normally capitalized, variable names are not. Hence this line
MyClass myClass = new MyClass();
In the code above I create an empty MyClass and then populate it with 5 items and then print that list. Then I create a new MyClass using the constructor which takes a MyClass parameter. This copies the items from the parameter list into the newly created MyClass (which is an ArrayList) and then removes the items from the MyClass passed as a parameter. Back in the main() method, I then print the contents of the two MyClass objects.
One thing which may be a little confusing is this line.
for(int i=0;i<ary.size();i++) add(ary.get(i));
the add() call doesn't refer to anything. What it really refers to is the newly created MyClass object which this constructor is building. This newly created object is the 'this' object. So the line above could be rewritten as
for(int i=0;i<ary.size();i++) this.add(ary.get(i));
Hopefully this helps a little. The problems you seem to be having are associated with object oriented concepts. You might try reading this
http://sepwww.stanford.edu/sep/josman/oop/oop1.htm -
Protected methods, what did i do wrong?
Hi there, I'm trying to understand why I cant access a Protected Method from a library that I'm trying to use..
Some guidance would be great:
public class Registration {
//Create new instance of ConnectionBean
ConnectionBean conBean = new ConnectionBean();
public Registration() {
public void regUser() {
String server = JOptionPane.showInputDialog( "Enter Server address" );
InetAddress inetaddress;
try {
conBean.connect( inetaddress = InetAddress.getByName( server ));
catch( UnknownHostException unknownhostexception ) {
Object aobj[] = {
"Cancel", "OK"
int i = JOptionPane.showOptionDialog(null, "Retry Server?", server +
": Not Responding", -1, 2, null, aobj, aobj[1]);
if( i == 1 )
regUser();
System.out.println( "Cannot resolve " + server + ":" + unknownhostexception.toString ());
return;
catch( IOException ioexception ) {
Object aobj1[] = {
"Cancel", "OK"
int j = JOptionPane.showOptionDialog( null, "Cannot Connect to:",
server,-1, 2, null, aobj1, aobj1[1] );
if( j == 1 )
regUser();
System.out.println( "Cannot connect " + server);
return;
System.out.println( "Registering User" );
registrationProcess();
public void registrationProcess () {
InfoQueryBuilder iqb = new InfoQueryBuilder();
InfoQuery iq;
IQRegisterBuilder iqRegb = new IQRegisterBuilder();
IQRegister iqReg = new IQRegister( iqRegb );
try {
//Need to getXMLNS packet method getXMLNS() is protected
iqReg.getXMLNS();
catch ( InstantiationException e ) {
System.out.println( "Error in building Registration packet" );
String username = JOptionPane.showInputDialog( "Enter: Username" );
String password = JOptionPane.showInputDialog( "Enter: Password" );
The error as would be expected:
Registration.java:96: getXMLNS() has protected access in org.jabber.jabberbeans.Extension.IQRegister
iqReg.getXMLNS();
^
1 error
Appreciate the help!! :)I tried to extend the class to make it a subclass of IQRegister (which holds the protected method) but I'm getting this error:
Reg.java:19: cannot resolve symbol
symbol : constructor IQRegister ()
location: class org.jabber.jabberbeans.Extension.IQRegister
public class Reg extends IQRegister {
^
1 error
Any ideas?
thanks -
Java access to protected methods
Hi,
I use a java toolkit, and want to access a class (Morphy) in it.
There is only one constructor function for class Morphy:
Morphy(WordNet wn).
And here is the doc of the class Morphy.
http://nlp.stanford.edu/nlp/javadoc/wn/doc/danbikel/wordnet/Morphy.html
As some methods in this class are protected, and I will call them.
Here is my code:
import danbikel.wordnet.WordNet;
import danbikel.wordnet.Morphy;
public class wn extends Morphy {
public void test(){
wn a=new wn();
a.morphWord("running","v"); // it is a protected method in Morphy
It just report an compile error: cannot find symbol: symbol : constructor Morphy().
Can anyone tell me how to fix the problem? I don't know how to add the constructor in my code.
Thanks a lot in advance.Read [this tutorial|http://java.sun.com/docs/books/tutorial/java/IandI/super.html] from "subclass constructors" and then think about what
wn a=new wn();tries to do what it can't do. -
Access to protected method is ot allowed
Hi,
there is class with a protected method. I get the message
"Access to protected method is ot allowed"
How must such methods be called if they are protected ?
Regards
sasErdem, please try to post in the correct forum. ABAP Objects questions belong in this forum, not general.
Second, Amit Khare is correct. The concept of Public/Protected/Private methods and attributes is not limited to ABAP Objects. It is a common concept to most object oriented programming languages. But if your read the ABAP Help on the appropriate keywords, then it is explained very clearly.
matt -
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 -
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 AMHello 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 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. -
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. -
Static methods in interface (Yes, once again!)
I know there has been many questions about why static methods in interfaces are not allowed. I know it is forbidden by the JLS. But does anyone know the exact reason for this? Is it just a design issue or are there technical difficulties with allowing it?
I can't think of any reason that it should be impossible to allow static methods in interfaces. I don't even think it would be very difficult to do. More importantly, it could probably be done without breaking existing code and existing JVMs (not too sure about the last one).
So once again: Was the choice of not allowing static methods in interfaces a design choice or a technical choice?A better example of what you are suggesting is surely ...
interface i {
static void one();
class a implements i {
static void one() {
// do something
class b implements i {
static void one() {
// do something else
}What would be the point of ever doing this?
You cant call i.one() as the method doesn't exist without an instance of an implementing class.
To actually ever be able to use that method you would effectively be casting an INSTANCE of a or b -> i. If you have an instance of an a or b then there is absolutely no reason for that method to be static.
If you wanted to implement some sort of class (ie static) behaviour then class a could call its own internal static method from within the 'one' method.
To get right to the point ... there isn't one. If it gets added to the language (and I can't see it in my wildest dreams) then Sun have lost their marbles, surely?
Unless someone can give a good example of when it might be correct and useful to do so? I can't even see how it would be a convenience as it is completely unusable, no? -
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,
JayI 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.
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