Why do we bifurcate Exception into Checked & Unchecked?

Exception is declared as checked exception. its subclasses includes checked as well as unchecked. but if i am gonna declare a userdefine exception by extending Excetion class, its behavin as checked bydefault....what is the feature which deferentiates between checked and unchecked??
how does JVM knows that its a checked or unchecked??
what is the basis for using checked and unchecked excetions??

http://java.sun.com/docs/books/jls/second_edition/html/exceptions.doc.html
JLS says it all pretty well.

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Convert checked exception into unchecked exception

Hi friends
I am little confused, When deciding on checked exceptions vs. unchecked exceptions. I went through the net. they are telling that
Use checked exceptions when the client code can take some useful recovery action based on information in exception. Use unchecked exception when client code cannot do anything.
Here what is the client code. which is the best way is checked exception good or is unchecked exception good or shall i simply tell catch(Exception e){...} or do i have to tell the particular exception like catch(SQLException) {..} instead of mentioning catch(excetpion){....}. I am so much confused...
Could you please tell me how to convert this code from checked exception into unchecked exception.
Connection con = null;
try {
 Class.forName("com.mysql.jdbc.Driver").newInstance();
 con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test",
 "root", "sheik");
 if(!con.isClosed())
 System.out.println("Successfully connected to " +
 "MySQL server using TCP/IP...");
 PreparedStatement ps = con.prepareStatement("DELETE FROM EMPLOYEE WHERE ID=?");
 ps.setInt(1, 3);
 System.out.println(ps.executeUpdate());
 } catch(Exception e) {
 System.err.println("Exception: " + e.getMessage());
 } finally {
 try {
 if(con != null)
 con.close();
 } catch(SQLException e) {
 System.out.println(e);
Thanks and Regards
Sherin Pooja

pierrot_2 wrote:
I think the words CHECKED and UNCHECKED are misleading.How so? Checked exceptions are those that are checked for by the compiler--requiring either catch or declare, and unchecked exceptions are those that the compiler doesn't check for and hence can be thrown anywhere without a catch or declare.
When a program can't deal with a situation at all, subclasses of <tt>Error</tt> are thrown and the program should terminate. When a program should continue to run, despite an anomaly of some sort, then programs should throw subclasses of <tt>Exception</tt>.No.
When there's a normal exceptional condition that can't be avoided simply by good coding--loss of network connection, disk full, insufficient permissions for an operatiion, and so on--throw a checked exception, that is, a subclass of Exception that is not a subclass of RuntimeException, such as IOExceptoin.
When there's a bug in your code, or in the caller of your code, or in some other code that you use, such as not ensuring preconditions are met, throw RuntimeException or a subclass. These are all unchecked. You generally do not catch these except at major layer boundaries.
When there's an internal error that the JVM has a good chance of not being able to recover from, such as running out of memory, Error or one of its subclasses is thrown. These are also unchecked, and it's pretty rare to explicitly throw one of these from code that you write. You generally do not catch these, except at major layer boundaries, and even then, probably in fewer situations than when you'd catch RuntimeException.

Checked & Unchecked Exceptions

What are Checked and UnChecked Exceptions.
When is it advisable to throw either of these.Can any one give me an example on these.

If an exception is "checked", you'll get a compiler
error if you don't catch it; if it's
"unchecked", you won't. Unchecked exceptions are
always subclasses of Error or RuntimeException.
Why have unchecked exceptions? If it were necessary
to catch NullPointerException and
ArrayIndexOutOfBoundsException every time one accessed
an array element, there would be very few Java
programmers.This is a very old post which I was browsing through. It wont be of much of an interest to anybody but to set the recoed straight for anybody who goes through it. RuntimeExceptions are also subclasses of Exception and secong unchecked Exceptions are not subclasses of Error.

"An error occurred during activation. Try again." Why can I not sign into imessage?

"An error occurred during activation. Try again." Why can I not sign into Imessage?

Hi,
You stated earlier that you had already deleted the "madrid" .plist with no effect.
Can I check you did this with the app closed down or at least restarted the app straight afterwards ?
If you did that close the app if open and access the ~/Library/Preferences folder again.
This time delete com.apple.imessage.bag.plist
This item stores the Apple server used for your Login to the iMessages server and contains a date/time reference.
Restarting the app after deleting this file will make it reconnect with the iMessages servers in a fresh manner which my solve things.
It may sort out any date/time issues with the stored date.
Messages is one of the app that Apple have "Sandboxed".
This means that some of it's operations are held away from other apps to prevent one app bringing down several others.
This is turn means that the route or path used by the app to Read and Write to the various .plists is different to the direct placing in ~/Library/Preferences.
The Path is ~/Library/Containers/com.apple.iChat/Data/Library/Preferences
Mostly the items in here are then Aliases that point to the actual originals in ~/Library/Preferences. However there are exceptions.
You can copy and paste the Path above in to the Finder > Go Menu > Go to Folder dialogue box to access this folder.
Once there use the Finder's View Menu > Show Path Bar.
This adds a collection of folders across the bottom of the Finder window.
Right click on the Preferences folder at the right hand list of the Path.
Chose the Get Info option.
In the Info panel scroll to the Bottom.
Your Shortname should appear (with (Me) as well) and you should have Read and Write Permissions
If you highlight this and then use the Cogwheel type iCon it should reveal you shortname again but in Greyed out form which mean you Own the File/folder
Repeat this for each containing folder until the Library item on the left (you don't need to do the Little House icon one)
You should have Read an Write Permissions and Own all of them.
Can you confirm this ?
8:04 pm Sunday; June 15, 2014
 iMac 2.5Ghz i5 2011 (Mavericks 10.9)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad

He XML message is going over to SRM from XI , but getting an application error (Exception) when checking in sxmb_moni on the SRM side

hi experts ,
we are using classic scenario (ECC 6.6 & SRM 7.0)
we have are configured Procure-to-Pay Scenario ,Note 1263876 - SAP SRM: Configuration of Procure-to-Pay Scenario.
but facing issue.
The XML message is going over to SRM from XI , but getting an application error (Exception) when checking in sxmb_moni on the SRM side. So we are not able to see the PR in the Sourcing cockpit in SRM.
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<SAP:Code area="ABAP">APPLICATION_ERROR</SAP:Code>
<SAP:P1 />
<SAP:P2 />
<SAP:P3 />
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Hi Vijay,
Can you tell us the interface name?
If it is stuck in FEH (Application Error) in SRM then you can check the detail error by going into tcode /n/sappo/ppo2.
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Why use customized / particular exceptions instead java.lang.Exception

Hi,
Do any of you guys know where can I find a theorical statement / explanation about why use particular / customized exceptions instead java.lang.Exception? I am aware that it consumes more resources and becomes a heavier object, as well as the clearness when coding and all that stuff; however, my boss wants to see a tech document where all this is clearly stated. Any resource over there?
Regards

It is better to throw specific--or at least module- or
package-specific--excpetions, rather than Exception,
because then the caller knows what to expect. However,
if you declare "throws Exception", the caller can
still catch IOException, SQLException, etc.,
separately. He'll just have to be a really good
guesser as to which ones he should catch.True.
Also, there's no point in declaring "throws
NullPointerException." Any method can throw it without
declaring it. If you generate your own NPE (or other
unchecked exception) inside the method, then you
should document it in the javadoc comments, but you
don't need to put it in the throws clause. It doesn't
do any harm, but it's redundant and cluttersome.It was an example and I wasn't feeling too creative....excuse me. ;-) But yeah, I've never thrown NPE ever.
I'm assuming overhead caused by extending classes.At
the worst, it would be miniscule, or so I wouldthink.
What overhead is created by extending classes?Hmm, I was under the impression that a class the extended another class, inherited all of the other classes data (variables, etc.). Hence, you get something like this:
SuperClass1 + SubClass1 + SubClassOfSubcCass1 = Memory usuage for SubClassOfSubClass1.
Since adding postivie number will always end up increasing data, SubClassOfSubClass1 will use more dtat than SuperClass1.
Am I wrong?

How to check/uncheck all check boxes in an insert-not-allowed block

Hi All,
I have a column of check box which is placed in a multirow block. This block's INSERT_ALLOWED property is set to false. The column of check box is not a database item and its insert_allowed property is to true. Now I use the following code which is in when-button-pressed trigger to control checking/unchecking all the check boxes:
go_block('selected_payment');
first_record;
loop
:cb_payflag:= 'N'; -- uncheck the check box
exit when (:system.last_record = 'true');
next_record;
end loop;
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Please help!
Thanks in advance.
Regards,
Vanessa

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Why to raise an exception?

Hello
I am trying to understand that why do we RAISE an Exception.
I was seeing some documentation. where it gave this example
(to check if any rows were updated or not, it uses SQL%NOTFOUND)
DECLARE
BEGIN
UPDATE Tablename
IF SQL%NOTFOUND
RAISE e_invalid_Item
END IF
COMMIT;
EXCEPTION
WHEN e_invalid_Item
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I was thinking
why cant we simply use the if statement to display. like below
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DBMS_OUTPUT.PUT_LINE('.................');
END IF
So why to raise an exception and then display DBMS_OUTPUT........
Why dont we just display it where it happened?
What is really and USE of raising an exception?
thank you

I am trying to understand that why do we RAISE an Exception."An exception is a runtime error or warning condition, which can be predefined or user-defined. Predefined exceptions are raised implicitly (automatically) by the runtime system. *User-defined exceptions must be raised explicitly by RAISE statements*. To handle raised exceptions, you write separate routines called exception handlers."
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/exception_definition.htm#LNPLS01316
http://www.oracle.com/pls/db102/homepage
http://www.oracle.com/pls/db112/homepage
You only catch exceptions when you expect them, and then deal with them, let them propagate to the caller.
Hopefully this (imo) classic 'rant' will make you understand better:
http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:1509245700346768268#tom1535781400346575552
Never ever swallow an exception by catching one and just 'dbms_output.put_line' it. Doing so, is the same as making success out of failure. Please read the link. It should give you ideas on how things (should) work.
Only catch exceptions you expect.

Why can't I sign into you tube

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No, that warning shouldn't be checked.
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Can you check/uncheck multiple songs in iTunes for syncing to iPod?

In a previous reply to this question, the answer given was that you can use Command apple key to uncheck or check groups of iTunes songs for syncing.
Actually this does not work.
Apple Commmand only gives you the possibility to check or uncheck the ENTIRE list of iTunes.. unless I am completely mad.
There must be a way to select say 5 songs from an album and check/uncheck them all at the same time. So that you can make a fresh selection of songs each time you sync to an iPhone or iPod
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ie what one needs to be able to do is highlight x number of songs at a time and then check or uncheck them as you go through the iTunes list to make a fresh syncing selection
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best
MS

AHXtreme42 wrote:
Once you have all of the selected items, RIGHT CLICK (or alt click whatever) one of those highlighted items and select either CHECK or UNCHECK SELECTION.
This is EXACTLY the point at which I get stuck - what is the actual key command for Right Click - it is not Alt Click or any combination, and looking for his in the iTunes help does not yield a result.
Please give me that actual key stroke combination to effect this last operation: I have always been able to select multiple tracks in the way you describe with Shift - but how to actually CHECK and UNCHECK a selection.. once the tracks are selected
Would much appreciate the answer to this

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Unable to check/uncheck older podcast episodes in iPod sync to iTunes 11.0

Hi,
I have a few podcasts in my iTunes where I have saved a large number of episodes. Now I have upgraded to the new version of iTunes I unable to check/uncheck older podcast episodes from iPod syncing - the finder window won't scroll to the bottom of the list, and just 'bounces' after scrolling past a certain number!
Not sure if this is a bug, or I'm overlooking something.
Thanks

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Unable to check / uncheck a checkbox in a JTable...

Hi all,
I know that a lot of people have asked this question before but I am unable to find a solution even after going all the messages. My issue is:
My initial rendering of the checkboxes inside the table works ok. I am using a TableCellRenderer and my input to determine the "checked/unchecked" is string like "true" or "false" and not boolean values. But I am unable to do check / uncheck any of the checkboxes.
I would really appreciate any pointers.
Thanks in advance.
Below is my code snippet:
public Component getTableCellRendererComponent(JTable table_,
Object value_, boolean isSelected_, boolean hasFocus_, int rowIndex_,
int colIndex_)
Component component = super.getTableCellRendererComponent(table_,
value_, isSelected_, hasFocus_, rowIndex_, colIndex_);
indicator = table_.getColumnModel().getColumnIndex("IND");
if (indicator == colIndex_)
     if (value_.equals("true")){
          component = new JCheckBox("", true);
     } else {
          component = new JCheckBox("", false);
     return component;
}

Your TableModel has to indicate that the column is editable. Your TableModel also has to implement setValueAt() so that when the user changes the value, it updates the data.
The table will know to use it's own boolean renderer/editor for that column because it knows what to do when a column returns a Boolean.

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Why do we bifurcate Exception into Checked & Unchecked?

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