Interfaces to replace multiple inheritence

Howdy,
I have, conceptually, the following situation: I have a Ball abstract class. The Ball has several
concrete methods. It also has an abstract method getAppearance (that would somehow return how a
Ball is visualized). I have several "adjective" subclasses that I would like to build from it, for example:
SpikyBall, GlowingBall, ColorBall, etc. I would like these classes to be concrete.
Additionally, I would like to have a concrete class of any permutation of this list of adjectives, for example:
SpikyColorBall, GlowingColorBall, SpikyGlowingColorBall. I want to accomplish this
using as little code rewriting as possible, and, hopefully, none at all.
Using certain other single letter languages that I won't name here, I used Multiple Inheritence. A
SpikyColorBall would inherit from both SpikyBall and ColorBall, who both inherited from
Ball. I was told I could accomplish this in Java using interfaces instead of multiple inheritence, which
Java doesn't support. How is this accomplished? Could you give me (or forward me to) a good
example? Again, the power I'm looking for is multiple inheritence's code-reusability.
As a side note, why did Java choose to use interfaces instead of multiple inheritence?

Courtesy of yawmark...
composition_v_inheritance
Bruce Eckel, author of Thinking In Java, has this to say about composition vs. inheritance:
When deciding between inheritance and composition, ask if you need to upcast to the base type. If not, prefer composition (member objects) to inheritance. This can eliminate the perceived need for multiple base types. If you inherit, users will think they are supposed to upcast.
Choose composition first when creating new classes from existing classes. You should only used inheritance if it is required by your design. If you use inheritance where composition will work, your designs will become needlessly complicated.
Bill Venners: Composition versus Inheritance
Use inheritance (of implementation) only when the class satisfies the following criteria:
1) "Is a special kind of," not "is a role played by a";
2) Never needs to transmute to be an object in some other class;
3) Extends rather than overrides or nullifies superclass;
4) Does not subclass what is merely a utility class (useful functionality you'd like to reuse); and
5) Within PD: expresses special kinds of roles, transactions, or things.
-- from Java Design: Building Better Apps and Applets (2nd Edition), by Peter Coad and Mark Mayfield

Similar Messages

Is multiple inheritence is possible in sap?

can any one help me?
is multiple inheritence possible in sap ?
and is one class can extend multiplre interfaces??

Hi,
Multiple inheritance as a concept is not allowed in ABAP Objects. But the effect and behaviour that you get by multiple inheritance is acheviable in ABAP objects with the help of interfaces. As follows.
An interface can inlcude more than one interface, that is an interface can extend more than one interface. Now if you have say interface1, interface2 and interface3.
interface4 can be declared to include all three other interfaces. And you class can include this interface4 in its interfaces tab.
Due to this your class gets the behviour(methods) that is defined in all ther interfaces. You can assign an object of this class to a reference of any one of these four interfaces. So one object can react to method calls on four different interfaces which is what you want to achevie in multiple inheritance.
Regards,
Sesh

I acheived Multiple Inheritence in JAVA !!!!!!!!

Hi,
Im in ob_imit2_a2 group. I can use member variables and methods of two(or more) classes in another class without importing them just like Multiple Inheritence in C++.
TECHNICAL COMMENTS REQUIRED
See Below
///////// Outer.java
public class Outer implements myInterface, myInterface2{
public Outer() {
System.out.println("outer class");
public void check()
     inter2.test();
     inter.test();
////////// myInterface.java
interface myInterface{
class interclass{
     interclass()
          System.out.println("SS");
     public void test()
          System.out.println("TEST");
public interclass inter=new interclass();
//////////myInterface2.java
interface myInterface2{
class interclass2{
     interclass2()
          System.out.println("SS 2");
     public void test()
          System.out.println("TEST 2");
public interclass2 inter2=new interclass2();
//////////// Main.java
public class Main {
public static void main(String abc[]) {
Outer o = new Outer();
     o.check();
}

Any and all variables declared in an interface are always implicitly public, static, and final; meaning that they are constants and NOT member variables. You can call these methods directly from the main method (a static scope) as well; meaning that they are not associated with any instance of the class Outer; i.e. they are NOT inherited.
The difference between inheritance (extending) and realization (implementing) is that when extending you inherit everything from your parent class, and while implementing you are taking up a role and agree to fulfill all the responsibilities (methods) of that role.

Is there an example to use interface to replace if then else pattern in F#

is there an example to use interface to replace if then else pattern in F#
i want to make match pattern with only one rule to represent dynamic number of rules which is use
let rec fun1 m number fun2param =
match m with
| fun2param(a,b,number) -> ****rewrite terms ****
let fun2param number =
if number = 1 then
function.....
elif number = 2 then
function ....
computing nightmare

In general, you use a match
let fun2param number =
match number with
| 1 -> function.....
| 2 -> function ....
in the same way as you would use a `switch` construct in 'C' in place of a repeated if/elif...elif/else
Your request is somewhat vague, so I'm not sure whether you would benefit from wrapping that behind an active pattern.

How to replace multiple occurences of space in a string to a single space?

How to replace multiple occurences of space in a string to a single space?

Hi,
try this code.
data : string1(50) type c,
          flag(1) type c,
          dummy(50) type c,
          i type i,
          len type i.
string1 = 'HI READ    THIS'.
len = strlen( string1 ).
do len times.
if string1+i(1) = ' '.
flag = 'X'.
else.
if flag = 'X'.
concatenate dummy string1+i(1) into dummy separated by space.
clear flag.
else.
concatenate dummy string1+i(1) into dummy.
endif.
endif.
i = i + 1.
enddo.
write : / string1.
write : / dummy.

Replace multiple space characters with a single space

Hi,
Oracle 11g R2.
Looking for a way to replace multiple space characters in a row with a single space. For example, the text "abc abc" should look like "abc abc". I tried toying with replace, but it only works for the case of 2 spaces. Need a solution for the cases where there could be 2 or more spaces.
select replace(column1, chr(32)||chr(32), chr(32)) from tablea

Hi,
If you had to do this without regular expressions, you could use:
SELECT REPLACE ( REPLACE ( REPLACE (str, ' ', '~ ')
                 , ' ~'
          , '~ '
          )     AS new_str
FROM    table_x;assuming there is some sub-string (I used '~' above) that never occurs right next to a space.
However, unless you're uisng Oracle 9 (or earlier, which you're not doing) you don't have to do this without regular expressions. As you can see, the way Solomon showed is much simpler.

Replacing multiple spaces with a single space

Hi friends,
I have a string. It can have zero/one/multiple spaces. I want to make the multiple spaces to single space.
Here are the cases:
1. ' a b c d efg h' should be changed to 'a b c d e f g h'
2. ' a b c d e f g h ' should be changed to 'a b c d e f g h'
3. 'a b c d e f g h' should not be changed
4. 'abcdefgh' should not be changed
Both REPLACE and TRANSLATE do not help. I don't want to go for LOOP logic. Please help me to get it in SQL query.
Thanks in advance!

Hi,
964559 wrote:
Hi friends,
I have a string. It can have zero/one/multiple spaces. I want to make the multiple spaces to single space.
Here are the cases:
1. ' a b c d efg h' should be changed to 'a b c d e f g h'One solution is to post your string on this site, and then copy it back again. (See below for a more serious solution .)
This site is doing exactly what you want the function to do: it replaces multiple consecutive spaces with a single space. As a result, it's hard to see what you mean.
To preserve spacing on this site, type these 6 characters
\(small letters only, inside curly brackets) before and after each section where you want spacing preserved.
2. ' a b c d e f g h ' should be changed to 'a b c d e f g h'
3. 'a b c d e f g h' should not be changed
4. 'abcdefgh' should not be changed
Both REPLACE and TRANSLATE do not help. I don't want to go for LOOP logic. Please help me to get it in SQL query.
Thanks in advance!Regular expressions make this easy:SELECT TRIM ( REGEXP_REPLACE ( str
, ' +'
) AS compressed_str
FROM table_x;
You can use nested REPLACE calls to get the same results, but it's messy.
Edited by: Frank Kulash on Feb 5, 2013 10:18 AM
Added TRIM

How to find and replace multiple cells at a time

I am doing repetitive work re find text in numbers but then replace following cells with text. How can I find and replace multiple cells at a time?
i.e. doing my own budget spreadsheet and coding all transactions with description and code

Did you try the "Find/Replace" dialog box?:
Then click the "Replace All" button in the bottom left.

Replace multiple spaces

Hi dear experts,
I need a function/procedure that replaces multiple spaces by one space.
(This is because of an Application Express representation of strings in a report).
(I have to replace ' ' by '_' in this post just because of the same phenomenon).
Strings like "This___is_an_________example"
should become " This_is_an__example".
I need something like:
create or replace function remove_multispaces(text_in in varchar2) return varchar2 is
begin
while instr(text_in,'__') >0 /* two blanks */
loop
execute immediate replace (text_in,'__','_'); /*replace 2 blanks by 1 */
end loop;
return (text_in);
end remove_multispaces;
But this is definitely not working.
Thank you for your help,
Hergen.

SQL> ed
Wrote file afiedt.buf
1 create or replace function replace_multispaces(in_str varchar2) return varchar2 is
2 out_str varchar2(100):=in_str;
3 begin
4 while(instr(out_str,'__')>0) loop
5 out_str:=replace(out_str,'__','_');
6 end loop;
7 return(out_str);
8 exception
9 when others then
10 dbms_output.put_line(sqlerrm);
11* end;
SQL> /
Function created.
SQL> select replace_multispaces('This___is_an_________example') from dual
2 ;
REPLACE_MULTISPACES('THIS___IS_AN_________EXAMPLE')
This_is_an_example
SQL>

Replacing multiple spaces with another character

i need to replace multiple spaces with another char in a string
my code is
Dim text as String="a bit much a little much" Dim arr As String() = text.Split({" "c}, StringSplitOptions.RemoveEmptyEntries)Dim newtext As String = String.Join(" ", arr) MsgBox(newtext)
it returns to "a bit much a little much "
But i want to replace only long spaces with "=" as "a bit much =a little much"
How can i do that?

This version uses two spaces to split the string and then trims any additional single spaces. It returns "a bit much = a little much".
Dim text As String = "a bit much a little much "
Dim parts() As String = text.Split({" "}, StringSplitOptions.RemoveEmptyEntries)
Dim newText As String
If parts.Length = 2 Then
newText = parts(0).Trim & " = " & parts(1).Trim
End If

Replace multiple characters to single character

Hi friends,
I would like to replace multiple characters in a string to a single character. The character may be a pipe (|) or a tilde (~).
For example "|||asdf||123|xyz||" should be changed to "asdf|123|xyz".
I use Oracle 11g2.
Thanks in advance!

Without regexp
with testdata as (
    select '||asdf||||123|xyz|' str from dual union all
    select 'asdf|123|||||||xyz||||' from dual union all
    select '||||||asdf|||123||||||xyz||||||' from dual
select
trim (both '|' from
    replace (
        replace (
            replace (str,'|','|'||chr(0))
            ,chr(0)||'|'
        ,chr(0)
) str
from testdata
STR
"asdf|123|xyz"
"asdf|123|xyz"
"asdf|123|xyz"
with regexp
with testdata as (
    select '||asdf||||123|xyz|' str from dual union all
    select 'asdf|123|||||||xyz||||' from dual union all
    select '||||||asdf|||123||||||xyz||||||' from dual
select
trim (both '|' from
    regexp_replace (
        str
        ,'\|+'
        ,'|'
) str
from testdata
STR
"asdf|123|xyz"
"asdf|123|xyz"
"asdf|123|xyz"
Message was edited by: chris227 regexp added

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Part 1 - Overwriting a Single Template
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What Ken has said also applied to
<img src="/assets/images/Lights/lights_select.jpg" width="400" height="400" alt="Lighting Thumbnails" />
which look for the JPG in http://davidcoshdesign.com/assets/images/Lights/lights_select.jpg rather than http://davidcoshdesign.com/nea/assets/images/Lights/lights_select.jpg
Gramps

Implementation of multiple inheritence

hi
i am goutam.how can we implement multiple inheritence in java.and how two super classes can be inherited in one sub class

keep it to one thread, please!

Multiple Inheritence/Const Compiler bug

I'm encountering what appears to be a bug when mixing multiple inheritence & const/non-const methods. The compiler (WorkShop 6 Update 2) is accepting the following ill-formed code :
class Base1 {
int a; //If Base1 is empty, the problem doesn't appear.
//A virtual function elicits the bug as well.
class Base2 {
public:
void mutator() { //non-const method
class Derived : public Base1, public Base2 {
class Foo {
private:
Derived my_derived;
public:
void f() const {
my_derived.mutator();
int main (int argc, char* argv[])
Foo my_foo;
my_foo.f();
Note how f() in class Foo is const, yet attempts to call mutator(), a non-const method that my_derived gets via inheritence to Base2. This is ill formed and should, I believe, yield a compiler error. If the code is just subtly changed, the correct error will appear. For instance, if Base1 is empty, the appropriate error appears. Alternatively, if Base2 appears before Base1 in Derived's inheritence list, then the appropriate error appears.
Is this a known problem? Is there a patch available? I'm very concerned that this bug is allowing const-incorrect code to be developed unknowingly, as it has in the project I'm involved in.
Thanks in advance for giving this your attention!
David Michael

The bug report hasn't been filed yet. If you have contract with Sun, please follow the service channel to file the report. Otherwise, I can do it for you. Please provide:
- O/S version
- Architecture
Please notice that if you don't have contract with sun, the bug might be in a low priority.
- Rose

Replacing multiple new line characters

how to replace multiple new line characters in a line.
Suppose for example my line contains Example1#####Example2##Example3###Example4,
then the output should be Example1#Example2#Example3#Example4.

Hi Sid,
You Can try this code
DATA: ld_string TYPE string,
      ld_string1 TYPE string,
      ld_string2 TYPE string,
      ld_string3 TYPE string.
ld_string = 'Example1#####Example2##Example3###Example4'.
REPLACE ALL OCCURRENCES OF '######' in ld_string with '#'.
REPLACE ALL OCCURRENCES OF '####' in ld_string with '#'.
REPLACE ALL OCCURRENCES OF '###' in ld_string with '#'.
REPLACE ALL OCCURRENCES OF '##' in ld_string with '#'.
write:/1 ld_string.
Regards
Pavan

Interfaces to replace multiple inheritence

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