Exception handling without instanceof
Imagine you have 3 Exceptions:
Exception Z
Exception Y extends Z
Exception X extends Y
In a method you do:
throw new X ("...
And that method declares that it throws an Exception:
throws Y
To access this method you have to do through an interface which declares:
throws Z
If you need to handle exceptions X, Y and Z differently, how can you do it without using instanceof which is supposedly bad design? The interface needs to throw the generic 'Z' exception because it doesn't know what exceptions the methods that it invokes will throw.
hi,
just have catch blocks for all exception types; it's
the actual type of the exception thrown that matters,
not the type of the exception that is declared to be
thrown.
try {
} catch (X x) {
} catch (Y y) {
} catch (Z z) {
}You're right! I thought it would catch the top level exception only! Thanks!
Similar Messages
-
Exception handling without BPM
Hello,
I have done exception handling with BPM.
i.e. when there exception comes in mapping I have use Block Exception Handler.
Can this be done without BPM.
Please snd me blog for it.
RegardsHi,
As explained by Michal it is correct, but in message mapping , we can raise an alert .
See the below links
Alerts with variables from the messages payload (XI) - UPDATED - /people/michal.krawczyk2/blog/2005/03/13/alerts-with-variables-from-the-messages-payload-xi--updated
Triggering XI Alerts from a User Defined Function - /people/bhavesh.kantilal/blog/2006/07/25/triggering-xi-alerts-from-a-user-defined-function
Regards
Chilla -
Mediator Exception Handling without fault policies
Hi,
Could somebody help me on defining exception handling to MEDIATOR component?
Is there is a way where we can do this without using the fault policies?
Thanks,
SV.Business faults are application-specific and are explicitly defined in the service WSDL file. You can handle business faults by defining the fault handlers in Oracle JDeveloper at design time. System faults occur because of some problem in the underlying system such as a network not being available. Oracle Mediator provides fault policy-based error handling for system faults.http://docs.oracle.com/cd/E21764_01/integration.1111/e10224/med_faulthandling.htm
Regards,
Anuj -
Hi all,
I'm trying to specify a method activity as an exception handler in the adfc-config. The problem is if I specify a view activity or a bounded task flow as the exception handler then it works fine, but if the exception handler is a method activity then it is not recognized. What could be the cause?. I need to execute a method when an exception occurs.
Version: 11.1.2.0
Edited by: NewBee on Apr 23, 2013 10:37 AMHi,
there should not be a problem with this and I recently did the same with JDeveloper 11g R2 (not sure which version of JDeveloper you use because you did not share this information). I assume you just marked the method activity as an exception handler without any other configuration? If so then set a break point to the managed bean method that you access from the method activity to see if it actually stops there. Also note that not all exceptions are handled by the controller exception handler. E.g an exception during render response phase (typically an exception in a managed bean) is not handled by the controller. Also you need to avoid the managed bean that handles the exception to itself throw one. This however you will see when debugging the bean.
Frank -
How to check was the object bound or not without exception handling?
context.lookup("someName");throws NameNotFoundException in case object was not bound to someName.
How to check was the object bound or not without exception handling?context.lookup("someName");throws NameNotFoundException in case object was not bound to someName.
How to check was the object bound or not without exception handling? -
Sync Send without a Exception Handler ??
hi..
Can a synchronous send step work with out an exception handler..??
im gettin my messages and combinin then n sendin via the sync send to call rfc , followeed by a send back to my server..
at this very stage it expects me to define a handler for the same for the sync send.
regards,
vishalhi bhavesh..
im doin the same...
Mode : Synch
Request Message
Response Message
Receiver From : Send Context
any reason fr it dmandin fr an exception handler../
it tch details i see the error as "no handler defined for this system exception"..
any inputs.. -
This question has been asked time and again, without any clear answers to it. I would appreciate if some one can help me on this.
I am developing a web application with the following architecture:
JSF page calls backing bean methods which calls the service methods. Now my service methods can throw different exceptions like ValidationException, BusinessException, SystemException etc.
Now, what i want to do is : If Validation/Business Exceptions are thrown show the error messages to the user on the same page from which the action was called. And if a SystemException is thrown navigate to a default error page.
How can i handle this thing? Any clues?Thanks for the reply BalusC,
I checked the log files (application log as well as server log) also and there is no other stack trace besides of the exception which i am throwing. Let me elaborate on the exact issue:
I am trying to handle concurrency issues in my application. For example, When two users simultaneously try to edit the same record, the user who first saves the changes successfully. Now when the second user tries to save the changes i want to show him a message that "This record has been modified after you opened it for edit. Please refresh your page and reapply the changes". To show this message i am throwing a BusinessException from my service, which in turn gets propagated to my saveAction method. The saveAction method needs to handle this exception and somehow should show the above message to the user.
To achieve this,
1. i tried catching the exception in my saveAction and added the necessary faces message to FacesContext object. But it does not work. Later i read the reason behind this too, that in the invoke application phase a new context will be created and the messages will not be available to it.
2. I then added the throws clause to my saveAction method, so that my default exception handler will handle it.
saveAction method signature :
public String saveAction () throws BusinessException {
//some code here for save
return null;
}This is my code for the ErrorHandler.jsp:
<body>
<h1 style="color: red">Error</h1><br/><%
// print stack trace.
ExceptionHandler exceptionHandler = new ExceptionHandler();
// unwrap ServletExceptions.
while (exception instanceof ServletException || exception instanceof FacesException ||
exception instanceof ApplicationException) {
if(exception instanceof ServletException) {
exception = ((ServletException) exception).getRootCause();
} else if(exception instanceof FacesException) {
exception = ((FacesException) exception).getCause();
} else if(exception instanceof ApplicationException) {
exception = ((ApplicationException) exception).getCause();
%><font color="red"><%=exceptionHandler.handleException(exception)%></font><br/></body>and this is my code for the handleException method defined in the ExceptionHandler.java:
public static String getMessage(final String msgKey, final Object args[]) {
String message = messages.getProperty(msgKey);
if(args != null) {
final String replaceArgs[] = (String[]) args;
for(int i = 0; i < replaceArgs.length; i++)
message = message.replaceFirst("{" + i + "}", replaceArgs);
return message;
public String handleException(final Throwable exception) {
logger.debug("handleException called..");
String errorMessage = "Unknown error occured.";
String stackTrace = "Stacktrace can not be found. Please check the logs for more details.";
String errorString = null;
final StringWriter stringWriter = new StringWriter();
if(exception != null) {
exception.printStackTrace (new PrintWriter (stringWriter));
stackTrace = stringWriter.toString();
errorMessage = getMessage(exception.getMessage(), null);
errorString = "<b>" + errorMessage + "</b> <br> </br> <br> <input id=\"show\" type=\"button\" value=\"Show Details >>\" onClick=\"toggle();\" /> <div id=\"errorStackTrace\" style=\"display:none;\" > <pre>" + stackTrace + "</pre> </div>";
return errorString;
With the help of this code, i am simply trying to navigate to the error page if an exception occurs and display the appropriate error message with the stacktrace.
The strange thing is, the ErrorHandler.jsp page correctly gets called, which in turn calls the handleException method which returns the formatted error string. (I checked this by adding log statements everywhere). But the system does not actually navigates to the ErrorHandler.jsp page and shows an alert with the following message : "Request error, status : 500 Internal Server Error message : "
Can someone help me figure out what exactly the problem is? -
PL/SQL 101 : Exception Handling
Frequently I see questions and issues around the use of Exception/Error Handling in PL/SQL. More often than not the issue comes from the questioners misunderstanding about how PL/SQL is constructed and executed, so I thought I'd write a small article covering the key concepts to give a clear picture of how it all hangs together. (Note: the examples are just showing examples of the exception handling structure, and should not be taken as truly valid code for ways of handling things)
Exception Handling
Contents
1. Understanding Execution Blocks (part 1)
2. Execution of the Execution Block
3. Exceptions
4. Understanding Execution Blocks (part 2)
5. How to continue exection of statements after an exception
6. User defined exceptions
7. Line number of exception
8. Exceptions within code within the exception block
1. Understanding Execution Blocks (part 1)
The first thing that one needs to understand is almost taking us back to the basics of PL/SQL... how a PL/SQL execution block is constructed.
Essentially an execution block is made of 3 sections...
+---------------------------+
| Declaration Section |
+---------------------------+
| Statements Section |
+---------------------------+
| Exception Section |
+---------------------------+
The Declaration section is the part defined between the PROCEDURE/FUNCTION header or the DECLARE keyword (for anonymous blocks) and the BEGIN keyword. (Optional section)
The Statements section is where your code goes and lies between the BEGIN keyword and the EXCEPTION keyword (or END keyword if there is no EXCEPTION section). (Mandatory section)
The Exception section is where any exception handling goes and lies between the EXCEPTION keyword at the END keyword. (Optional section)
Example of an anonymous block...
DECLARE
.. declarative statements go here ..
BEGIN
.. code statements go here ..
EXCEPTION
.. exception handlers go here ..
END;
Example of a procedure/function block...
[CREATE OR REPLACE] (PROCEDURE|FUNCTION) <proc or fn name> [(<parameters>)] [RETURN <datatype>] (IS|AS)
.. declarative statements go here ..
BEGIN
.. code statements go here ..
EXCEPTION
.. exception handlers go here ..
END;
(Note: The same can also be done for packages, but let's keep it simple)
2. Execution of the Execution Block
This may seem a simple concept, but it's surprising how many people have issues showing they haven't grasped it. When an Execution block is entered, the declaration section is processed, creating a scope of variables, types , cursors, etc. to be visible to the execution block and then execution enters into the Statements section. Each statment in the statements section is executed in turn and when the execution completes the last statment the execution block is exited back to whatever called it.
3. Exceptions
Exceptions generally happen during the execution of statements in the Statements section. When an exception happens the execution of statements jumps immediately into the exception section. In this section we can specify what exceptions we wish to 'capture' or 'trap' and do one of the two following things...
(Note: The exception section still has access to all the declared items in the declaration section)
3.i) Handle the exception
We do this when we recognise what the exception is (most likely it's something we expect to happen) and we have a means of dealing with it so that our application can continue on.
Example...
(without the exception handler the exception is passed back to the calling code, in this case SQL*Plus)
SQL> ed
Wrote file afiedt.buf
1 declare
2 v_name VARCHAR2(20);
3 begin
4 select ename
5 into v_name
6 from emp
7 where empno = &empno;
8 dbms_output.put_line(v_name);
9* end;
SQL> /
Enter value for empno: 123
old 7: where empno = &empno;
new 7: where empno = 123;
declare
ERROR at line 1:
ORA-01403: no data found
ORA-06512: at line 4
(with an exception handler, we capture the exception, handle it how we want to, and the calling code is happy that there is no error for it to report)
SQL> ed
Wrote file afiedt.buf
1 declare
2 v_name VARCHAR2(20);
3 begin
4 select ename
5 into v_name
6 from emp
7 where empno = &empno;
8 dbms_output.put_line(v_name);
9 exception
10 when no_data_found then
11 dbms_output.put_line('There is no employee with this employee number.');
12* end;
SQL> /
Enter value for empno: 123
old 7: where empno = &empno;
new 7: where empno = 123;
There is no employee with this employee number.
PL/SQL procedure successfully completed.
3.ii) Raise the exception
We do this when:-
a) we recognise the exception, handle it but still want to let the calling code know that it happened
b) we recognise the exception, wish to log it happened and then let the calling code deal with it
c) we don't recognise the exception and we want the calling code to deal with it
Example of b)
SQL> ed
Wrote file afiedt.buf
1 declare
2 v_name VARCHAR2(20);
3 v_empno NUMBER := &empno;
4 begin
5 select ename
6 into v_name
7 from emp
8 where empno = v_empno;
9 dbms_output.put_line(v_name);
10 EXCEPTION
11 WHEN no_data_found THEN
12 INSERT INTO sql_errors (txt)
13 VALUES ('Search for '||v_empno||' failed.');
14 COMMIT;
15 RAISE;
16* end;
SQL> /
Enter value for empno: 123
old 3: v_empno NUMBER := &empno;
new 3: v_empno NUMBER := 123;
declare
ERROR at line 1:
ORA-01403: no data found
ORA-06512: at line 15
SQL> select * from sql_errors;
TXT
Search for 123 failed.
SQL>
Example of c)
SQL> ed
Wrote file afiedt.buf
1 declare
2 v_name VARCHAR2(20);
3 v_empno NUMBER := &empno;
4 begin
5 select ename
6 into v_name
7 from emp
8 where empno = v_empno;
9 dbms_output.put_line(v_name);
10 EXCEPTION
11 WHEN no_data_found THEN
12 INSERT INTO sql_errors (txt)
13 VALUES ('Search for '||v_empno||' failed.');
14 COMMIT;
15 RAISE;
16 WHEN others THEN
17 RAISE;
18* end;
SQL> /
Enter value for empno: 'ABC'
old 3: v_empno NUMBER := &empno;
new 3: v_empno NUMBER := 'ABC';
declare
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at line 3
SQL> select * from sql_errors;
TXT
Search for 123 failed.
SQL>
As you can see from the sql_errors log table, no log was written so the WHEN others exception was the exception that raised the error to the calling code (SQL*Plus)
4. Understanding Execution Blocks (part 2)
Ok, so now we understand the very basics of an execution block and what happens when an exception happens. Let's take it a step further...
Execution blocks are not just a single simple block in most cases. Often, during our statements section we have a need to call some reusable code and we do that by calling a procedure or function. Effectively this nests the procedure or function's code as another execution block within the current statement section so, in terms of execution, we end up with something like...
+---------------------------------+
| Declaration Section |
+---------------------------------+
| Statements Section |
| . |
| +---------------------------+ |
| | Declaration Section | |
| +---------------------------+ |
| | Statements Section | |
| +---------------------------+ |
| | Exception Section | |
| +---------------------------+ |
| . |
+---------------------------------+
| Exception Section |
+---------------------------------+
Example... (Note: log_trace just writes some text to a table for tracing)
SQL> create or replace procedure a as
2 v_dummy NUMBER := log_trace('Procedure A''s Declaration Section');
3 begin
4 v_dummy := log_trace('Procedure A''s Statement Section');
5 v_dummy := 1/0; -- cause an exception
6 exception
7 when others then
8 v_dummy := log_trace('Procedure A''s Exception Section');
9 raise;
10 end;
11 /
Procedure created.
SQL> create or replace procedure b as
2 v_dummy NUMBER := log_trace('Procedure B''s Declaration Section');
3 begin
4 v_dummy := log_trace('Procedure B''s Statement Section');
5 a; -- HERE the execution passes to the declare/statement/exception sections of A
6 exception
7 when others then
8 v_dummy := log_trace('Procedure B''s Exception Section');
9 raise;
10 end;
11 /
Procedure created.
SQL> exec b;
BEGIN b; END;
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at "SCOTT.B", line 9
ORA-06512: at line 1
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Procedure A's Declaration Section
Procedure A's Statement Section
Procedure A's Exception Section
Procedure B's Exception Section
6 rows selected.
SQL>
Likewise, execution blocks can be nested deeper and deeper.
5. How to continue exection of statements after an exception
One of the common questions asked is how to return execution to the statement after the one that created the exception and continue on.
Well, firstly, you can only do this for statements you expect to raise an exception, such as when you want to check if there is no data found in a query.
If you consider what's been shown above you could put any statement you expect to cause an exception inside it's own procedure or function with it's own exception section to handle the exception without raising it back to the calling code. However, the nature of procedures and functions is really to provide a means of re-using code, so if it's a statement you only use once it seems a little silly to go creating individual procedures for these.
Instead, you nest execution blocks directly, to give the same result as shown in the diagram at the start of part 4 of this article.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure b (p_empno IN VARCHAR2) as
2 v_dummy NUMBER := log_trace('Procedure B''s Declaration Section');
3 begin
4 v_dummy := log_trace('Procedure B''s Statement Section');
5 -- Here we start another execution block nested in the first one...
6 declare
7 v_dummy NUMBER := log_trace('Nested Block Declaration Section');
8 begin
9 v_dummy := log_trace('Nested Block Statement Section');
10 select empno
11 into v_dummy
12 from emp
13 where empno = p_empno; -- Note: the parameters and variables from
parent execution block are available to use!
14 exception
15 when no_data_found then
16 -- This is an exception we can handle so we don't raise it
17 v_dummy := log_trace('No employee was found');
18 v_dummy := log_trace('Nested Block Exception Section - Exception Handled');
19 when others then
20 -- Other exceptions we can't handle so we raise them
21 v_dummy := log_trace('Nested Block Exception Section - Exception Raised');
22 raise;
23 end;
24 -- ...Here endeth the nested execution block
25 -- As the nested block handled it's exception we come back to here...
26 v_dummy := log_trace('Procedure B''s Statement Section Continued');
27 exception
28 when others then
29 -- We'll only get to here if an unhandled exception was raised
30 -- either in the nested block or in procedure b's statement section
31 v_dummy := log_trace('Procedure B''s Exception Section');
32 raise;
33* end;
SQL> /
Procedure created.
SQL> exec b(123);
PL/SQL procedure successfully completed.
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Nested Block Declaration Section
Nested Block Statement Section
No employee was found
Nested Block Exception Section - Exception Handled
Procedure B's Statement Section Continued
7 rows selected.
SQL> truncate table code_trace;
Table truncated.
SQL> exec b('ABC');
BEGIN b('ABC'); END;
ERROR at line 1:
ORA-01722: invalid number
ORA-06512: at "SCOTT.B", line 32
ORA-06512: at line 1
SQL> select * from code_trace;
TXT
Procedure B's Declaration Section
Procedure B's Statement Section
Nested Block Declaration Section
Nested Block Statement Section
Nested Block Exception Section - Exception Raised
Procedure B's Exception Section
6 rows selected.
SQL>
You can see from this that, very simply, the code that we expected may have an exception was able to either handle the exception and return to the outer execution block to continue execution, or if an unexpected exception occurred then it was able to be raised up to the outer exception section.
6. User defined exceptions
There are three sorts of 'User Defined' exceptions. There are logical situations (e.g. business logic) where, for example, certain criteria are not met to complete a task, and there are existing Oracle errors that you wish to give a name to in order to capture them in the exception section. The third is raising your own exception messages with our own exception numbers. Let's look at the first one...
Let's say I have tables which detail stock availablility and reorder levels...
SQL> select * from reorder_level;
ITEM_ID STOCK_LEVEL
1 20
2 20
3 10
4 2
5 2
SQL> select * from stock;
ITEM_ID ITEM_DESC STOCK_LEVEL
1 Pencils 10
2 Pens 2
3 Notepads 25
4 Stapler 5
5 Hole Punch 3
SQL>
Now, our Business has told the administrative clerk to check stock levels and re-order anything that is below the re-order level, but not to hold stock of more than 4 times the re-order level for any particular item. As an IT department we've been asked to put together an application that will automatically produce the re-order documents upon the clerks request and, because our company is so tight-ar*ed about money, they don't want to waste any paper with incorrect printouts so we have to ensure the clerk can't order things they shouldn't.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2 cursor cur_stock_reorder is
3 select s.stock_level
4 ,r.stock_level as reorder_level
5 ,(r.stock_level*4) as reorder_limit
6 from stock s join reorder_level r on (s.item_id = r.item_id)
7 where s.item_id = p_item_id;
8 --
9 v_stock cur_stock_reorder%ROWTYPE;
10 begin
11 OPEN cur_stock_reorder;
12 FETCH cur_stock_reorder INTO v_stock;
13 IF cur_stock_reorder%NOTFOUND THEN
14 RAISE no_data_found;
15 END IF;
16 CLOSE cur_stock_reorder;
17 --
18 IF v_stock.stock_level >= v_stock.reorder_level THEN
19 -- Stock is not low enough to warrant an order
20 DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
21 ELSE
22 IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
23 -- Required amount is over-ordering
24 DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
||to_char(v_stock.reorder_limit-v_stock.stock_level));
25 ELSE
26 DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
27 -- Here goes our code to print the order
28 END IF;
29 END IF;
30 --
31 exception
32 WHEN no_data_found THEN
33 CLOSE cur_stock_reorder;
34 DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
35* end;
SQL> /
Procedure created.
SQL> exec re_order(10,100);
Invalid Item ID.
PL/SQL procedure successfully completed.
SQL> exec re_order(3,40);
Stock has not reached re-order level yet!
PL/SQL procedure successfully completed.
SQL> exec re_order(1,100);
Quantity specified is too much. Max for this item: 70
PL/SQL procedure successfully completed.
SQL> exec re_order(2,50);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL>
Ok, so that code works, but it's a bit messy with all those nested IF statements. Is there a cleaner way perhaps? Wouldn't it be nice if we could set up our own exceptions...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2 cursor cur_stock_reorder is
3 select s.stock_level
4 ,r.stock_level as reorder_level
5 ,(r.stock_level*4) as reorder_limit
6 from stock s join reorder_level r on (s.item_id = r.item_id)
7 where s.item_id = p_item_id;
8 --
9 v_stock cur_stock_reorder%ROWTYPE;
10 --
11 -- Let's declare our own exceptions for business logic...
12 exc_not_warranted EXCEPTION;
13 exc_too_much EXCEPTION;
14 begin
15 OPEN cur_stock_reorder;
16 FETCH cur_stock_reorder INTO v_stock;
17 IF cur_stock_reorder%NOTFOUND THEN
18 RAISE no_data_found;
19 END IF;
20 CLOSE cur_stock_reorder;
21 --
22 IF v_stock.stock_level >= v_stock.reorder_level THEN
23 -- Stock is not low enough to warrant an order
24 RAISE exc_not_warranted;
25 END IF;
26 --
27 IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
28 -- Required amount is over-ordering
29 RAISE exc_too_much;
30 END IF;
31 --
32 DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
33 -- Here goes our code to print the order
34 --
35 exception
36 WHEN no_data_found THEN
37 CLOSE cur_stock_reorder;
38 DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
39 WHEN exc_not_warranted THEN
40 DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
41 WHEN exc_too_much THEN
42 DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
||to_char(v_stock.reorder_limit-v_stock.stock_level));
43* end;
SQL> /
Procedure created.
SQL> exec re_order(10,100);
Invalid Item ID.
PL/SQL procedure successfully completed.
SQL> exec re_order(3,40);
Stock has not reached re-order level yet!
PL/SQL procedure successfully completed.
SQL> exec re_order(1,100);
Quantity specified is too much. Max for this item: 70
PL/SQL procedure successfully completed.
SQL> exec re_order(2,50);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL>
That's better. And now we don't have to use all those nested IF statements and worry about it accidently getting to code that will print the order out as, once one of our user defined exceptions is raised, execution goes from the Statements section into the Exception section and all handling of errors is done in one place.
Now for the second sort of user defined exception...
A new requirement has come in from the Finance department who want to have details shown on the order that show a re-order 'indicator' based on the formula ((maximum allowed stock - current stock)/re-order quantity), so this needs calculating and passing to the report...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2 cursor cur_stock_reorder is
3 select s.stock_level
4 ,r.stock_level as reorder_level
5 ,(r.stock_level*4) as reorder_limit
6 ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7 from stock s join reorder_level r on (s.item_id = r.item_id)
8 where s.item_id = p_item_id;
9 --
10 v_stock cur_stock_reorder%ROWTYPE;
11 --
12 -- Let's declare our own exceptions for business logic...
13 exc_not_warranted EXCEPTION;
14 exc_too_much EXCEPTION;
15 begin
16 OPEN cur_stock_reorder;
17 FETCH cur_stock_reorder INTO v_stock;
18 IF cur_stock_reorder%NOTFOUND THEN
19 RAISE no_data_found;
20 END IF;
21 CLOSE cur_stock_reorder;
22 --
23 IF v_stock.stock_level >= v_stock.reorder_level THEN
24 -- Stock is not low enough to warrant an order
25 RAISE exc_not_warranted;
26 END IF;
27 --
28 IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
29 -- Required amount is over-ordering
30 RAISE exc_too_much;
31 END IF;
32 --
33 DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
34 -- Here goes our code to print the order, passing the finance_factor
35 --
36 exception
37 WHEN no_data_found THEN
38 CLOSE cur_stock_reorder;
39 DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
40 WHEN exc_not_warranted THEN
41 DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
42 WHEN exc_too_much THEN
43 DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
||to_char(v_stock.reorder_limit-v_stock.stock_level));
44* end;
SQL> /
Procedure created.
SQL> exec re_order(2,40);
Order OK. Printing Order...
PL/SQL procedure successfully completed.
SQL> exec re_order(2,0);
BEGIN re_order(2,0); END;
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at "SCOTT.RE_ORDER", line 17
ORA-06512: at line 1
SQL>
Hmm, there's a problem if the person specifies a re-order quantity of zero. It raises an unhandled exception.
Well, we could put a condition/check into our code to make sure the parameter is not zero, but again we would be wrapping our code in an IF statement and not dealing with the exception in the exception handler.
We could do as we did before and just include a simple IF statement to check the value and raise our own user defined exception but, in this instance the error is standard Oracle error (ORA-01476) so we should be able to capture it inside the exception handler anyway... however...
EXCEPTION
WHEN ORA-01476 THEN
... is not valid. What we need is to give this Oracle error a name.
This is done by declaring a user defined exception as we did before and then associating that name with the error number using the PRAGMA EXCEPTION_INIT statement in the declaration section.
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2 cursor cur_stock_reorder is
3 select s.stock_level
4 ,r.stock_level as reorder_level
5 ,(r.stock_level*4) as reorder_limit
6 ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7 from stock s join reorder_level r on (s.item_id = r.item_id)
8 where s.item_id = p_item_id;
9 --
10 v_stock cur_stock_reorder%ROWTYPE;
11 --
12 -- Let's declare our own exceptions for business logic...
13 exc_not_warranted EXCEPTION;
14 exc_too_much EXCEPTION;
15 --
16 exc_zero_quantity EXCEPTION;
17 PRAGMA EXCEPTION_INIT(exc_zero_quantity, -1476);
18 begin
19 OPEN cur_stock_reorder;
20 FETCH cur_stock_reorder INTO v_stock;
21 IF cur_stock_reorder%NOTFOUND THEN
22 RAISE no_data_found;
23 END IF;
24 CLOSE cur_stock_reorder;
25 --
26 IF v_stock.stock_level >= v_stock.reorder_level THEN
27 -- Stock is not low enough to warrant an order
28 RAISE exc_not_warranted;
29 END IF;
30 --
31 IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
32 -- Required amount is over-ordering
33 RAISE exc_too_much;
34 END IF;
35 --
36 DBMS_OUTPUT.PUT_LINE('Order OK. Printing Order...');
37 -- Here goes our code to print the order, passing the finance_factor
38 --
39 exception
40 WHEN exc_zero_quantity THEN
41 DBMS_OUTPUT.PUT_LINE('Quantity of 0 (zero) is invalid.');
42 WHEN no_data_found THEN
43 CLOSE cur_stock_reorder;
44 DBMS_OUTPUT.PUT_LINE('Invalid Item ID.');
45 WHEN exc_not_warranted THEN
46 DBMS_OUTPUT.PUT_LINE('Stock has not reached re-order level yet!');
47 WHEN exc_too_much THEN
48 DBMS_OUTPUT.PUT_LINE('Quantity specified is too much. Max for this item: '
||to_char(v_stock.reorder_limit-v_stock.stock_level));
49* end;
SQL> /
Procedure created.
SQL> exec re_order(2,0);
Quantity of 0 (zero) is invalid.
PL/SQL procedure successfully completed.
SQL>
Lastly, let's look at raising our own exceptions with our own exception numbers...
SQL> ed
Wrote file afiedt.buf
1 create or replace procedure re_order(p_item_id NUMBER, p_quantity NUMBER) is
2 cursor cur_stock_reorder is
3 select s.stock_level
4 ,r.stock_level as reorder_level
5 ,(r.stock_level*4) as reorder_limit
6 ,(((r.stock_level*4)-s.stock_level)/p_quantity) as finance_factor
7 from stock s join reorder_level r on (s.item_id = r.item_id)
8 where s.item_id = p_item_id;
9 --
10 v_stock cur_stock_reorder%ROWTYPE;
11 --
12 exc_zero_quantity EXCEPTION;
13 PRAGMA EXCEPTION_INIT(exc_zero_quantity, -1476);
14 begin
15 OPEN cur_stock_reorder;
16 FETCH cur_stock_reorder INTO v_stock;
17 IF cur_stock_reorder%NOTFOUND THEN
18 RAISE no_data_found;
19 END IF;
20 CLOSE cur_stock_reorder;
21 --
22 IF v_stock.stock_level >= v_stock.reorder_level THEN
23 -- Stock is not low enough to warrant an order
24 [b]RAISE_APPLICATION_ERROR(-20000, 'Stock has not reached re-order level yet!');[/b]
25 END IF;
26 --
27 IF v_stock.stock_level + p_quantity > v_stock.reorder_limit THEN
28 -- Required amount is over-ordering
29its nice article, have put up this one the blog
site,Nah, I don't have time to blog, but if one of the other Ace's/Experts wants to copy it to a blog with reference back to here (and all due credit given ;)) then that's fine by me.
I'd go for a book like "Selected articles by OTN members" or something. Does anybody have a list of links of all those mentioned articles?Just these ones I've bookmarked...
Introduction to regular expressions ... by CD
When your query takes too long ... by Rob van Wijk
How to pipeline a function with a dynamic number of columns? by ascheffer
PL/SQL 101 : Exception Handling by BluShadow -
Quick question, gurus.... From exception handling perspective, is "no_data_found" inclusive of "others". In other words, if my query returns no data and I use "others" without a "no_data_found" will the exception utilize "others"?
Thanks.
I give points.
I supposed I could have tested this using a quick anon block but didn't think about it just now.
Edited by: sreese on Apr 13, 2012 3:54 PMsreese wrote:
Quick question, gurus.... From exception handling perspective, is "no_data_found" inclusive of "others". In other words, if my query returns no data and I use "others" without a "no_data_found" will the exception utilize "others"?Try it out and let us know, keeping in mind that if your code expects to encounter NO_DATA_FOUND then you need to trap that exception and handle it appropriately. How can you possibly pretend to know how to handle an error that is by it's very definition "unknown" (when others).
sreese wrote:
I give points.
I supposed I could have tested this using a quick anon block but didn't think about it just now.I'd prefer you keep the points and try this out yourself ... much better way to learn. -
Exception handling for Null/Incorrect input parameters
Hi,
My BI Publisher report has input parameter name as <region>. It is a text field and is mandatory parameter.
But if I run the report without giving value to the parameter it gives the error "The report cannot be rendered because of an error, please contact the administrator."
How can I handle this scenario so that User defined message is displayed, asking user to give correct input.
I am using Oracle BI Publisher 10.1.3.3.3
Is there some documentation available for Exception Handling/How to display User defined messages in case of error?
My requirement is that after displaying the error message (say for example "Please enter Region name"), the report processing should stop there only and it should not display the blank pages of the rest of the PDF template.
Thanks in advance.Hi,
Thanx for the solution.
I have another query linked to this issue. My requirement is that after displaying the error message (say for example "Please enter Customer name"), the report processing should stop there only and it should not display the blank pages of the rest of the PDF template.
Thanx in advance. -
Exception Handling in bounded taskflows - expected behaviour
Hi,
I'm currently reviewing exception handling in bounded task flows and some things does not seems to be very clear for me.
(q1) Does it make sense that a bounded task flow calls a method (via a method activity) defined on the page definition of another page (outside of the BTF) by using a #{data.xxxmyPageDef.myMethodName.execute} EL expression?
(q2) Is is correct to expect the application to execute the method marked as ExceptionHandler in the taskflow, whenever an exception occurs?
(q3) I created 5 different scenarios where I call a service method which throws an exception, from within a page fragment of the BTF.
(q3 – sc1) Call a service method through the binding layer of the current page (by using #{bindings.xxx.execute})
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.(q3 – sc2) Call a service method through a task flow method activity using #{bindings.xxx.execute}
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.(q3 – sc3) Call a service method through a task flow method activity using #{data.myPageFragementPagedef.xxx.execute} (accessing the pageDef of the page fragment)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.(q3 – sc4) Call a service method through a task flow method activity using #{data.myPageContainingThePageFragmentPageDef.xxx.execute} (accessing the page containing the BTF region)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage. (q3 – sc5) Call a service method through a task flow method activity using #{data.aPageOutsideTheBTFPageDef.xxx.execute} (accessing a page outside the BTW)
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage. (q4) How can it be possible that – without an exception handler – exceptions occur when calling method activities, without the exceptions being translated to FacesMessages?
Thanks in advance,
Koen Verhulst
JDeveloper 11.1.1.4Koen,
+(q1) Does it make sense that a bounded task flow calls a method (via a method activity) defined on the page definition of another page (outside of the BTF) by using a #{data.xxxmyPageDef.myMethodName.execute} EL expression?+
No. Exceptions should be handled locally.
+(q2) Is is correct to expect the application to execute the method marked as ExceptionHandler in the taskflow, whenever an exception occurs?+
Only for exceptions that are before Render Response. The Render Response Phase is not handled in ADFc. So exceptions that occur in managed beans may fall through
+(q3) I created 5 different scenarios where I call a service method which throws an exception, from within a page fragment of the BTF.+
+(q3 – sc1) Call a service method through the binding layer of the current page (by using #{bindings.xxx.execute}) Result: A dialog containing the exception message appears.+
This is what I expected. Althought, the exception handler method does not seems to be invoked.
The binding layer has an error handler you can override in the DataBinings.cpx file
+(q3 – sc2) Call a service method through a task flow method activity using #{bindings.xxx.execute}+
Result: A dialog containing the exception message appears.
This is what I expected. Althought, the exception handler method does not seems to be invoked.
Again, you use the binding layer to invoke the service
+(q3 – sc3) Call a service method through a task flow method activity using #{data.myPageFragementPagedef.xxx.execute} (accessing the pageDef of the page fragment)+
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
Never use such a call. Its bad practice as there is no guarantee the container you reference is active. Always have the method call activity have its own binding defined when accessing a method call activity. I know there are lots of example floating aroundthat you #{data ...} and many are from 10.1.3. This should be avoided alltogether though
+(q3 – sc4) Call a service method through a task flow method activity using #{data.myPageContainingThePageFragmentPageDef.xxx.execute} (accessing the page containing the BTF region)+
Result: Nothing happens.
This is not what I expected. Although, the exception handler method does not seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
Again, this is not a proper use of the ADF framework.
+(q3 – sc5) Call a service method through a task flow method activity using #{data.aPageOutsideTheBTFPageDef.xxx.execute} (accessing a page outside the BTW)+
Result: Nothing happens. This is not what I expected. Although, the exception handler method does nog seems to be invoked, I expect the ADF Error Handler to create a FacesMessage.
accessing a page outside the BTW (!!!) This should ring a worst practices alarm on your laptop (obviously doesn't do it either)
+(q4) How can it be possible that – without an exception handler – exceptions occur when calling method activities, without the exceptions being translated to FacesMessages?+
Exceptions are not handled in a single place but stacked. The business service raises an exception and passes it to the binding layer if not handled. The binding layer handles the exception and if it can't passes it to ADFc. ADFc can handle this exception if it is not during Render Response.
Bottom line: There is no single point of exception handling. So as a recommendation for best practices
- Catch and handle exceptions as close as possible to their origins
- If things can go wrong, thy will - use try/catch blocks in managed beans
- Use an exception handling activity in all bounded task flows. In the case of task flow call activities being used exceptions can bubble up to the caller. However, this would take users out of their current application context
- Exceptions not handled in ADFc can be intercepted by overriding the application task flow exception handler (used by the exception handler activities). This would give you a chance e.g. to handle issues during Render Response
- Never fight the framework, never bend the framework: Don't use out of scope access to page definitions and resources. Exception handling is not a replacement for bad code practices (sorry for saying this, its not meant to be rude) :-)
Though I don't have a qualified numbers of bugs open for exception handling in ADF between 11.1.1.4 and now (and some that are open), but there are issues reported in this area. If there is something that really feels wrong, please go ahead and file a bug and provide a test case for development to have a look. The Render Response issue, for example is something we are aware of and that is in discussion (afaik knows, there is a change in exception handling in JSF 2 that may have an impact to what we can do in ADFc).
thanks
Frank -
Exception handling for Scanner console input
I'm trying to add exception handling to a Scanner console to deal with exceptions caused by non-numeric input. My idea was to do use a try/catch in a for loop and break if no exception occurs.
Whats happening is the "iNumber = console.nextInt(); " does nothing on subsequent retries, when an exception occurs. That is, I enter "123w", an InputMismatchException occurs, goes into the first catch block, hits "continue" and goes back into the for loop, hits the "iNumber = console.nextInt(); ", then immediately blows through it without executing. Thus, I hit my max loop count and exit with iNumber = 0.
I'm thinking I may need to instantiate "static Scanner console = new Scanner(System.in);" again in the event of an exception?
Thanks for any feedback. I'm brand new at Java and learning as fast as I can :)
Here is the code:
class ConsoleInput
public ConsoleInput() // constructor
static Scanner console = new Scanner(System.in);
public int GetInput()
int iNumber = 0;
for(int i=0; i<3; i++)
try
System.out.print("Please enter a number: ");
iNumber = console.nextInt(); // get console input
break;
catch(java.util.InputMismatchException ex)
continue;
catch(Exception ex)
continue;
return iNumber;
}public class Scratch {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
boolean gotAValidInt = false;
int theInt;
System.out.println("Enter an int");
do {
try {
theInt = sc.nextInt();
gotAValidInt = true;
catch (InputMismatchException exc) {
System.out.println("Not an int. Try again.");
sc.next(); // consume the non-int that nextInt couldn't consume
} while (!gotAValidInt);
}There are different ways you could structure your loop, but the key is that when nextInt throws an exception, you have to call next() in the catch block to consume the token that nextInt couldn't.
Edited by: jverd on May 2, 2008 1:52 PM -
Hi everybody,
I want to develop an application and need exception handling.
I have a helper application that contains this classes:
MyADFPhaseListener extends ADFPhaseListener that return this: return new MyFacesPageLifecycle(),
MyErrorHandler extends DCErrorHandlerImpl,
MyFacesPageLifecycle extends FacesPageLifecycle that contain this methods:
prepareModel(LifecycleContext ctx) that set my errorhandler with this: ctx.getBindingContext().setErrorHandler(new MyErrorHandler(true));
and
reportErrors(PageLifecycleContext ctx){
DCBindingContainer bc = (DCBindingContainer)ctx.getBindingContainer();
if (bc != null) {
ArrayList<Exception> exceptions =new ArrayList<Exception>();
exceptions = bc.getExceptionsList();
if (exceptions != null) {
/*handle exceptions*/
My problem is here:
when throw an exception in my app like this: throw new JboException("Don't do that.", "101", null);
after create pagelifecycle and calling prepareModel(), reporterros() dose not call....!!!
why?
Edited by: 859070 on May 15, 2011 9:35 PMwhen click a button and call action of this button.
please note:
My helper application and main application are apart. I deploy helper application to jar file and use this jar file in main application.
Maybe exceptions don`t send to reportErrors() method in MyPageLifeCycle class, because i create a test class like this:
public class test {
public static void main(String[] args) throws SQLException {
ArrayList<Exception> exss = new ArrayList<Exception>();
exss.add(new JboException("A fatal exception is occurred",
"103", null));
exss.add(new NullPointerException());
exss.add(new SQLException());
MyFacesPageLifecycle efpl =new MyFacesPageLifecycle();
efpl.errorReporter(exss);
Body of errorReporter(ArrayList<Exception>) method is like reportErrors(PageLifecycleContext) just parameter is different.
public void errorReporter(ArrayList<Exception> excs) {
if (excs != null) {
for (Exception exception: excs) {
if(exception instanceof JboException){
System.out.println("JBOException is occurred here: "+exception.getMessage());
else if(exception instanceof SQLException){
System.out.println("SQLException is occurred here");
else if(exception instanceof NullPointerException){
System.out.println("NullPointerException is occurred here");
else{
and this handle exceptions list. My opinion is that exceptions between different applications(helper and main) are lost. is this correct? -
BPM - Exception handling in multiline mapping
Hi,
I have in a BPM a block with processing mode ParForEach containing a transformation and then a send step.
If the transformation (mapping) generates an exception for one of the lines of the multiline variable being processed, no subsequent lines are passed to the send step.
I want the process to execute the mapping for each line and then send messages corresponding to lines without error. How can I do?
Thank you
SimonaHi Simona,
I also feel that Michal had suggested the correct solution. Not sure why you are saying that the error gets propagated, if you have defined a proper Exception handling for the inner block.
But regarding your design for "ParForEach", I am not sure whether you really need to carry out a transformation step for each Block instance, in which case you can keep the transformation step before the "ParForEach" block.
Rgds
R Chandrasekhar (RC) -
what is the best way to handle errors in BizTalk ?
We are using web services, databases.
Is ESB Exception handling preferred to others ? any better suggestions please ?
MBHYou don't need custom-Itineraries /On Ramp/Off Ramp for repaid and resubmit using ESB portal. But you need to have receive ports, send ports, orchestration which comes with ESB tool kit for this purpose. When a failure is published to ESB-bus,
"catch all” exception send port will pick it up and publish it to the ESB Exceptiondb. Then using the ESB portal you can edit/repair the message and resubmit it directly from the portal without using the ESB-Toolkit artefacts like Itineraries /On Ramp/Off
Ramp.
Refer this article where author uses this feature without any custom ESB-toolkit artefacts
http://seroter.wordpress.com/2010/01/18/considerations-when-retrying-failed-messages-in-biztalk-or-the-esb-toolkit/
One option to route a failed message to the ESB Portal one must turn on routing for failed messages on the send port. This results in the failed message being routed to the ESB Exception database along with the exception details. Even in orchestration's
you can submit the failed message to ESBException DB from where you can repair and resubmit the message.
Refer this article for more help on this context:
Routing exceptions on send ports to the ESB Exception Management Portal without turning on routing for failed messages
If this answers your question please mark it accordingly. If this post is helpful, please vote as helpful by clicking the upward arrow mark next to my reply.
Maybe you are looking for
-
I can't get to camera roll, the ALBUMS banner is over the top of it.
-
Nokia C6-00 -- Using MP3 for alarm tone?
Is there a way to use a song for an alarm tone on the C6-00? Thanks in advance.
-
Shift Abbreviations in Shift Planning
Hello gurus, Anyone ever experienced this? i need to update It2003 with a period work schedule rule and not the Daily work schedule rule and it looks as though this is SAP STD that you can only work wirh DWS in shift planning. Anyone with some cranck
-
Keep tilda on top of wallpaper ("fork to background") ?
Hi there, I'm running a lightweight system based on Openbox, tint2, PCManFM, and I use tilda as terminal emulator. I really love to have it on top of my wallpaper, but I also have an Openbox keybind which shows my desktop (minimize all opened applica
-
Will TuringTest2s corrupt iTunes recovery guide work for a Mac?
Empty/corrupt iTunes library after upgrade/crash Im desperate to sort my issue and I think this could help but I'm not sure if these steps are the same for a Mac. I dont want to break anything and I want my content back. Im trying to fix an issue whe