Control flow: catch statement

Hi there!,
Need to know where the control passes if an error is caught in a catch statement.
Suppose no alternative error handling code has been specified. Where would control go if a terminal error occured? Would it just carry on to the next statement in the general flow or would it terminate the application/applet. By terminal, i mean something like getParameter() returning null etc..
Any help that sheds light on this is appreciated greatly.
To make this clearer, how would the program know when to exit a try catch statement if it falls into a catch statement that gave a nonsensical value?

You should be careful with your terms, "an error is
caught" has a very specific meaning in Java. Errors
(instances of java.lang.Error and it's subclasses)
should not be caught (that is, with a try-catch
statement) in your code because they signal more
serious problems than usual (like ClassNotFoundError,
LinkageError, VirtualMachineError, and so on), not in
switch statements or otherwise.In certain situations they should be caught.
If I create a stand alone app with a client GUI it doesn't matter to the user if a null pointer exception, because of programmer error, occurs in the database layer. But they are going to get real upset if the app just abruptly exits which is what is going to happen if the GUI layer doesn't catch all of the exceptions. And although it is possible that one of those exceptions makes it impossible to do anything at all, it is much more likely that the GUI can at least display a message to the user before exiting. And write the stack trace to a file as well.
This is true at the interface between any two layers. And some applications will be able to continue. I certainly don't want a J2EE server exiting because one of the new beans isn't working correctly. It won't stop the other beans from working.

Similar Messages

Use control flow statement to evalute signals

Hi,
I have a number of steps in my sequence file such that when TS runs it looked like this:
SignalA >20 pass
Signal B <= 30 pass
Now I wish to use some control flow statements like While and If loops so that I could create steps like this:
While ( SignalA > 20)
Problem is there are no "SignalA" in the TS expressions. I tried putting together an expression like RunState.Sequence.?? (some unique id of the step)Result.step = "failed". But the While loop can't seem to evaluate to True
Any suggestion would be appreciated.
Thanks!
ph2

Hey ph2,
I'm not sure what your goal is with this but there is probably a better way to accomplish what you want.
Where is SignalA coming from? A VI? A dll? Do you only have to acquire it once or do you need to get it every iteration of the loop? Is the step that acquires it inside the While statement or is it an asynchronous thread? Why not just store it to a Local or FileGlobal and then access that. It would be easier.
BTW- If SignalA > 20 step is a Numeric Limit then you can access it by using Step.Result.Numeric.
Let me know exactly what your goal here is and I could possibly help you find a better solution.
Cheers,
jigg
CTA, CLA
teststandhelp.com
~Will work for kudos and/or BBQ~

Better control flow?

Actually this is a general question I've been wondering for a while...
As the title states, I'm looking for a better control flow statement for what I planned.
I have 4 variables that determine types of pipe in a program in my main class. There are 6 possible pipe types.
For example Type 1 would have plastic grade = 5-7, color = 2, inner reinforcement = yes etc.
My main method determines which type the client chose, (if it matched one of the types or not so if all 4 were true then it matches x type.)
It's going to get really ugly if I use ifs and I don't think using a case statement would work.
Any suggestions in what I can use?

Unless you're just referring to getting user input and using it to look up a pipe >type?That would be what I'm doing, if I could figure out how to get the input variables from my applet class to the class that sorts out which pipe they picked.
Except the variables had to be defined within a method so the try catch statments could be added to them to catch the nfe as most of them are converted from String to int.
Let me suggest you to use nested switch case to solve the problemHmm, ok, I'll look into that. Would nested ifs suffice?
Message was edited by:
Yuriy_Ivanov

Use exception to control flow?

I use validateExcelFile(File excelFile) to validate whether a file has valid excel format,
when file is in invalid format, I have two options:
1) return the error message in validate method:
public String validateExcelFile(File excelFile) {
String errorMsg = "";
if(errorMsg.length == 0) {
return null;
} else {
return errorMsg;
Or
2)Throw out a exception containing errorMsg
public void validateExcelFile(File excelFile)
throws InvalidExcelFormatException {
String errorMsg = "";
if(errorMsg.length != 0) {
throw new InvalidExcelFormatException(errorMsg);
The context in which the validate method is invoked needs to delete any invalid excel file according to the validate result, option 2 has the good that if there is another validate method and it also throws out the same exception when a file is invalid then I can place the two method in one
try{
validateMethod1( excelFile );
validateMethod2( excelFile );
} catch (InvalidFormatException ex) { // deletes invalid file } statement, it is more clear than to check every method's returned error message, but I doubt whether it is good practice to control flow with exception instead of
flow statements like if.
Thanks.
StuartS
Edited by: StuartS on Oct 24, 2007 8:35 PM

TimSparq wrote:
You are correct, it is best practice not to controll flow with exceptions.
Perhaps your validate message could just return a boolean and you can do something like:
if (!validateExcelFile(file)) {
// delete file
Yeah, I was thinking of it more from a security validation standpoint, but if you simply want to accomplish an action as the result of a bad format, then you're definitely better off having a boolean function.

Reg control flow

I have an message statement of type error,
After the message statement I have another executable statement.
How to change the control flow from after displaying the error message to that executable statement.
thnks in advance.
Edited by: jean liker on Mar 12, 2008 6:27 AM

if sy-subrc NE 0.
message 'You Dont have authorization' type 'E'.
// logout user.
call 'SYST_LOGOFF'.
endif.
so after displaying the error message, i want to logoout the user.
Edited by: jean liker on Mar 12, 2008 6:57 AM

Conditon in control flow that needs sequencing

Hi,
Is there a way to make two Analysis Services DDL tasks, that can potentially run in parallel in a control flow (according to a condition) to run sequentially via configuration ?

just create a variable of type boolean in ssis. set default value as False. then in control flow have three tasks, one execute sql task and your two analysis services DDL tasks
Give a dummy statement inside execute sql task like say SELECt 1 after defining a db connecton. link the execute sql task to one of analysis services ddl tasks ( say ddl1). Change precedence constraint option as Expression and Constraint, set constraint
to OnSuccess and Expression to
@Variable == False
add the other analysis services ddl task (dd2) and dont connect anything to it. take the output from it and connect to dd1 and give precedence constraint option as Expression and Constraint, set constraint to OnSuccess and Expression to below
@Variable == True
Also set Multiple constraints option as Logical OR for ddl1
This will make sure when variable is true ddl2 executes first followed by dd1 and when variable is 1 they execute parallely
You can change variable value through configuration (XML file/SQL table value)
Please Mark This As Answer if it helps to solve the issue Visakh ---------------------------- http://visakhm.blogspot.com/ https://www.facebook.com/VmBlogs

Control flow

I still have a problem dealing with control flow statements, e.g. if(current != null)
What does that mean?

I still have a problem dealing with control flow
statements, e.g. if(current != null)
What does that mean?This tutorial might help you:
http://java.sun.com/docs/books/tutorial/java/nutsandbolts/flow.html
Sorry, Sun still didn't get the url tags fixed.

Dialog control flow case not opening in new browser window

Hello -
Using JDev 11gR1.
I have a page fragment that contains a table of command links like so:
        <af:commandLink text="#{row.id}" id="cl2"
                        action="#{reportRunnerBean.runReportAction}"
                        useWindow="true" windowHeight="500" windowWidth="500">
          <f:param value="#{row.id}" name="reportId" id="p2"/>
        </af:commandLink>the runReportAction method returns the String: "dialog:runReport"
in my page flow, the page fragment has a control flow case with the outcome "dialog:runReport" that leads to a URL View with the URL setting set to #{pageFlowScope.reportUrl}
(the reportRunAction places a string in page flow scope with the key of "reportUrl". in case it matters, the url is external to the application)
When I click on the link, I am directed to the correct URL. However, it does not open in a new browser window - it takes up the main browser window.
Is there something obvious that I am doing wrong?
Thank you for reading this,
-- Scott

Well, I couldn't figure out why the dialog wasn't working correctly, so I changed my page to use a server listener to handle the logic I wanted and just used af:goLink instead of a command link. That command link above became:
          <af:goLink text="#{row.id}" id="gl1"
                     destination="#{row.reportUrl}"
                     targetFrame="_blank">
            <af:clientAttribute name="reportId" value="#{row.id}"/>
            <af:clientListener method="logReport" type="click"/>
            <af:serverListener type="LogReportEvent"
                               method="#{reportListBean.logReportInvocation}"/>
          </af:goLink>with the following client listener:
    <af:resource type="javascript">
      function logReport(evt) {
          var component = evt.getSource();
          var reportIdParam = component.getProperty("reportId");
          AdfCustomEvent.queue(component,
                               "LogReportEvent",
                               { reportId: reportIdParam}, false);
    </af:resource>and code in the bean:
    public void logReportInvocation(ClientEvent clientEvent) {
            String reportId =
                (String)clientEvent.getParameters().get("reportId");
            //...do something w/reportId here...
    }Thanks to anyone who took the time to read this.

"catch is unreachable" compiler error with java try/catch statement

I'm receiving a compiler error, "catch is unreachable", with the following code. I'm calling a method, SendMail(), which can throw two possible exceptions. I thought that the catch statements executed in order, and the first one that is caught will execute? Is their a change with J2SE 1.5 compiler? I don't want to use a generic Exception, because I want to handle the specific exceptions. Any suggestions how to fix? Thanks
try {
SendMail(....);
} catch (MessagingException e1) {
logger.fine(e1.toString());
} catch (AddressException e2) {
logger.fine(e2.toString());
public String SendMail(....) throws AddressException,
MessagingException {....

I found the problem:
"A catch block handles exceptions that match its exception type (parameter) and exception types that are subclasses of its exception type (parameter). Only the first catch block that handles a particular exception type will execute, so the most specific exception type should come first. You may get a catch is unreachable syntax error if your catch blocks do not follow this order."
If I switch the order of the catch exceptions the compiler error goes away.
thanks

Programatically calling control flows from java code

Hi all,
I have a bounded taskFlow that uses pageFragments. This flow is a region in a page(.jspx).
In my page fragment, I have a inputComboboxListOfValues with a ValueChangeListener code in a java bean.
I want when a value is changed, to programatically call "controll flow" (this one has: "From Activity Id" -the page fragment with that inputComboboxListOfValues, and "To Activity Id" - the default Activity on this task Flow).
So when the value change, practically I want to restart the flow programatically and pass the selected value as input parameter.
Since the inputComboboxListOfValues is not like a button where in the "Action" property you can set the Control Flow and navigate somewhere, the only option I have is to programatically cause navigation from java code (example: the value change listener code).
Can this be achieved?
Any advice is helpfull.

Hi,
Absolutely, you can do it using the NavigationHandler. Try the following in you value change listener:
FacesContext context = FacesContext.getcurrentInstance();
NavigationHandler handler = context.getApplication().getNavigationHandler();
handler.handleNavigation(context, null, outcome);
// Render the response after that phase, the button actions should not be called
context.renderResponse();
// Add the following line if you want to prevent further value change listeners to be called
// throw new AbortProcessingException();Regards,
~ Simon

Biginner's question about catch statement

hi im just a biginner
normally u guys write catch statement like
catch (FileNotFouldException exception)
System.out.println (exception);
something like that . but what is the exception here
is it object name? or class name or what
i mean the word exception after FileNotFoundException
i just don't understand

It's the type of the exception to which the catch block should apply.
You could have this:
try {
// stuff
} catch (FileNotFoundException fnfe) {
fnfe.printStackTrace();
} catch (IOException ioe) {
ioe..printStackTrace();
} catch (NumberFormatException nfe) {
nfe.printStackTrace();
} catch (Exception x) {
ex..printStackTrace();
}Note that FNFE extends IOE, so if the IOE is caught first, the FNFE would be caught in that block too. That's why you catch the general Exception last - if you do it at all.

Bounded-Task-Flow Page Fragment Control Flow Help

jDeveloper: 11.1.1.0.2
I am having an issue trying to figure out the correct way to use control flow cases between a bounded-task-flow with page fragments and an unbounded-task-flow page. We have taken the approach in our application to have a few shell / container pages to host bounded-task-flows made up of page fragments to facilitate re-usability and to speed up development. There are 4 or 5 shell pages on the applications unbounded-task-flow. As of now, we have about 20 page fragments that are implemented as bounded-task-flows. These fragments don't do much now, meaning there is only a single fragment in each bounded-task-flow. The issue I am having is trying to invoke a control flow navigation action from one of the fragments to load a different shell page.
For Example, shellPage1.jspx contains fragment-flow-1 as a region. In my adfc-config.xml I have shellPage1.jspx and shellPage2.jspx, with control flow cases "toShell1" and "toShell2" respectively connecting the two pages. I have a link's action bound to the "toShell2" within the fragment that makes up fragment-flow-1. When the application is run, shellPage1.jspx and its fragment are displayed. But clicking on the link in the fragment ("toShell2") does absolutely nothing. It does not navigate me to the shellPage2.jspx as expected. What am I doing wrong here or do not understand?
If the fragment is included as a JSP include, and not a bounded task flow include, everything works as expected. This is not desirable as we then need to copy the fragment's pageDef into the shellPage's pageDef to get the DataControls to function.
If the faces-config.xml is used instead, and a JSF navigation case is used, it will also work as expected. This is not desirable because we really don't want to be mixing adcf-config and faces-config.
So I am really stumped here.... Thanks in advance!

Hi there:
In your case, the adfc-config.xml has the control flow case between shell pages. And the task-flow-N.xml or your-task-flow.xml for each page fragment by default doesn't inherit control flow case from their containing shell page. In your case, in the page fragment task-flow.xml, you should add a "Parent Action" to flow to shell page2 for example. The outcome of "Parent Action" would be "toShell2" if calling from ShellPage1 page fragment.
Is this 'Correct' or 'Helpful' for you? Please mark it as so if it does.
Good luck,
Alex

From where i can understand the control flow and architecture of JVM?

i want to know control flow and architecture of JVM?
Where i can know from?
if some one wish to explain you can here also.

makpandian wrote:
No it s not broken.
As per your experience,tell me some links.Per my experience I don't need links. I could build the VM both from the general level and the specific levels by referring only to the VM spec.
And I read the book I suggested, first edition, years ago. Although with many other books.
Conversely if I wanted to find a link now then I would use google.

Catch Statement, Help!!!

I need help with a catch statement that will give an error message when Letters are put in, i need this as im only working with numebers, Heres what i have done already. When i build the code i always get
";" expected
Thanks for your Help
jMenuKmperHourMileActionPerformed(java.awt.event.ActionEvent e)
try
String Number = ToBeConverted.getText();
double amount = new Double(Number).doubleValue();
total = (amount*.621371192);
Converted.setText("= " + total);
ToBeConverted.setEditable(false);
catch(NumberFormatException nfx)
Converted.setText(Number + " is not a valid number!");
}

Your try/catch statement is bad. You have too many { } brackets in there.
The format should be
try{
// code which throws Exceptions
String Number = ToBeConverted.getText();
double amount = new Double(Number).doubleValue();
total = (amount*.621371192);
Converted.setText("= " + total);
ToBeConverted.setEditable(false);
catch(NumberFormatException nfx){
// error handler
Converted.setText(Number + " is not a valid number!");
}

Why do we want use 'Data Flow Task' to 'Data Flow Tast' in Control Flow?

I found an example in my company's SSIS package folders. In Control Flow, it has one data flow connected to the other. Both of them are importing data from flat file and then exported to database. I think these two are kind of at the same level and cannot
see any reasons to conncect them together.
Thanks & Happy Thxgiving,
Gavin

Hi Gavin,
Just as Arthur said, if there is no relationship between those two data flow tasks, we don’t have to connect them together. If they connect together, maybe there are some relationship between them.
According to your description, both of the data flow tasks are importing data from flat file and then exported to database. It seems that there is no direct relationship between them. Another possibility is that there is a precedence constraint between them.
The precedence constraint can be based on a combination of the first execution results and the evaluation of expressions. We can check the issue by double-check the connection string between them.
The following screenshot is for your reference:
If there are any other questions, please feel free to ask.
Thanks,
Katherine Xiong
Katherine Xiong
TechNet Community Support

Control flow: catch statement

Similar Messages

Maybe you are looking for