Difference between empty and zero

I'm trying to set a PDF calculation to NOT trigger if a field is blank, but trigger if the field is set to any number, including 0 (zero).
Right now I have:
if (getField("blahblah").value == "") {event.value = "";}
else {event.value = calculation here;}
The calcultion isn't running if field "blahblah" is specifically set to 0. How do I fix this?
Thanks!

Hi Bob! Thanks for the tip. I discovered that three equal signs inherently distinguishes between "" and 0. I believe the value as string method would work, but the below does as well:
if (getField("blahblah").value === "") {event.value = "";}
else {event.value = calculation here;}

Similar Messages

Difference between Null and null?

What is the difference between null and NULL?
When is each used?
Thanks,

veryConfused wrote:
There is a null in java, but no NULL. null means no value. However, when assigning value, the following is different:Although the empty String has no special role. Null means, the referential type is not assigned (doesn't refer) to a specific object. The empty String is just another object though, so seeing it or pointing it out as something special when it actually isn't at all (no more special than new Integer(0) or new Object[0]) just adds to the confusion.

Difference between ok_code and sy-ucomm

Hi,
Can any one tell me the difference between ok_code and sy-ucomm

Hi,
Actually OK_CODE and SY-Ucomm are the same. But experts suggest use of OK code for following reason:
In each PAI event that a user triggers by choosing either a pushbutton on the screen or an element in a GUI status, the corresponding function code is placed into the system field SYST-UCOMM or SY-UCOMM and placed in the OK_CODE field (as long as the function code is not empty). Empty function codes are placed in neither the SY-UCOMM field nor the OK_CODE field.
In your ABAP programs, you should work with the OK_CODE field instead of SY-UCOMM. There are two reasons for this: Firstly, the ABAP program has full control over fields declared within it, and secondly, you should never change the value of an ABAP system field. However, you should also always initialize the OK_CODE field in an ABAP program for the following reason:
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Difference between CHAR and VARCHAR2 datatype

Difference between CHAR and VARCHAR2 datatype
CHAR datatype
If you have an employee name column with size 10; ename CHAR(10) and If a column value 'JOHN' is inserted, 6 empty spaces will be inserted to the right of the value. If this was a VARCHAR column; ename VARCHAR2(10). How would it handle the column value 'JOHN' ?

The CHAR datatype stores fixed-length character strings, and Oracle compares CHAR values using blank-padded comparison semantics.
Where as the VARCHAR2 datatype stores variable-length character strings, and Oracle compares VARCHAR2 values using nonpadded comparison semantics.
This is important when comparing or joining on the columns having these datatypes;
SQL*Plus: Release 10.2.0.1.0 - Production on Pzt Au 6 09:16:45 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
SQL> conn hr/hr
Connected.
SQL> set serveroutput on
SQL> DECLARE
2 last_name1 VARCHAR2(10) := 'TONGUC';
3 last_name2 CHAR(10) := 'TONGUC';
4 BEGIN
5 IF last_name1 = last_name2 THEN
6 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is equal to -' || last_name2
|| '-');
7 ELSE
8 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is NOT equal to -' || last_n
ame2 || '-');
9 END IF;
10 END;
11 /
-TONGUC- is NOT equal to -TONGUC -
PL/SQL procedure successfully completed.
SQL> DECLARE
2 last_name1 CHAR(6) := 'TONGUC';
3 last_name2 CHAR(10) := 'TONGUC';
4 BEGIN
5 IF last_name1 = last_name2 THEN
6 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is equal to -' || last_name2
|| '-');
7 ELSE
8 DBMS_OUTPUT.PUT_LINE ( '-' || last_name1 || '- is NOT equal to -' || last_n
ame2 || '-');
9 END IF;
10 END;
11 /
-TONGUC- is equal to -TONGUC -
PL/SQL procedure successfully completed.
Also you may want to read related asktom thread - "Char Vs Varchar" http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1542606219593
and http://tahitiviews.blogspot.com/2007/05/less-is-more-more-or-less.html
Best regards.

Difference between -1 and null in the targettype filed

Hi
Could anyone advise what is the difference between -1 and null in the targettype filed in marketing documents?
For example, in Sales Quotation - Rows (QUT1) table, I found for some open sales quotations, the field is null however the DB help file suggest the default value is -1 so I suppose it should be -1 for open documents.
Many thanks for your advisory.

Hi, Qian!
I investigated that "-1" value appears in targettype field in Sales Quotation Rows (QUT1 table) when you Dublicate a Sales Quotation document (Ctrl + D). And NULL value appears when you create a new document without dublicating.
In case you want to equal these 2 "empty"-values using T-SQL, you can use ISNULL(targettype, -1) function - this will give you -1 for both the "empty"-values
HTH!
Message was edited by: Aleksey Kuznetsov

What is the difference between "= NULL" and "IS NULL" in SQL?

Hi,
I believe there is a difference between "= NULL" and "IS NULL" comparsion, but I couldn't find it. Anyone knows the difference?
Thanks,
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Aha, thanks:
SQL> create table william_test_tab (col binary_double);
Table created.
SQL> insert into william_test_tab
2 select rownum / (rownum - 1) from user_tables where rownum < 4;
select rownum / (rownum - 1) from user_tables where rownum < 4
ERROR at line 2:
ORA-01476: divisor is equal to zero
SQL> insert into william_test_tab
2 select 1d * rownum / (rownum - 1) from user_tables where rownum < 4;
3 rows created.
SQL> select * from william_test_tab;
       COL
       Inf
2.0E+000
1.5E+000
3 rows selected.
SQL> select * from william_test_tab where col is infinite;
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1 row selected.
SQL>

ABST2 - Differences between Assets and G/L accts

Hi Experts
We are working on ECC 6.0 and INR is our local currency.
At the end of FY 2007 by mistake direct postings were made to Dep Fund Account which is a Recon a/c and FY 2007 was closed
And because of which FI-GL and FI-AA doesnt match by INR 37353.71 (amt posted in above doc) as shown in ABST2
I've referred SAP notes 104567 & 69225 and found the note 69225 relevant to follow as the difference has not resulted in the current or open years.
So we have passed direct entry which is exactly the reversal of entry posted above using ABF1 (INR -37353.71)
After posting the 2nd document, in ABST2 another line has appeared of INR -37353.71. Although the sum for my recon GL is now zero.
The output of ABST2 is as below now -
Sc Acct no.   BusA Year SG 1st local difference LCurr Doc.no.    Period
AS 31100                2009               37,353.71-        INR     W004
AS 31100                2009               37,353.71         INR     W004       999
When I come out of ABST2 , addition to 1st, error no 2 is also coming which I thought would disappear.
1.Differences between assets and G/L accts in the balance carried forward
     Message no. MQ555
2.Differences between assets and G/L accounts at the key date
     Message no. MQ557
Is still something else needs to be done?
Or can I move ahead as the summation of the difference is now zero?
Please suggest.
Kapil

We referred to SAP and they suggeted that the tagging of W004 in both the lines means that now there is no error even system prompts it as error.
So we continued with the transactions and after closing the FY 2009, today when we run ABST2, we dont get any error messages as there is no difference left between Assets & GL.

Difference between MBBS and MB5L report.

All capital inventory till FY-2008-09 was transferred to revenue inventory by movemnt typr 411-Q in MB1B.All the codes those were transferrd are now appearing in MBBS but with zero value. However these codes are appearing in MB5L with value under GL 132006 (for capital items) and having value of 1.08 crores (0.94 crore for imported items and 0.14 crore for revenue items). The GL for all these codes neds to be changed to 132000 (revenue inventory GL) so that in MB5L also these items appear as revenue items.As of today GL of all the codes appearing under GL 132006 are to be changed to 132000 except code 496700086.
now, changes are reflected in report MBBS but not showing correct information in MB5L report..
Please guide what is the difference between MBBS and MB5L report.
Regards
SHreya

Hi,
MBBS gives stock values of "project'" and "sales order" only.
MB5L gives total stock value .

Difference between logical and virtual terms

Hello,
This is not purely oracle question; but in documentation so many times we find 2 terms:
A. Logical
B.Virtual.
So what is the principle difference between logical and virtual? As I know physical is that which I can see and touch; while logical/virtual is that is imaginary. We say tablespace is logical not virtual; while Java Virtual Machine; not Java Logical Machine. So I want to know; what is the principle difference; why two words for an imaginary thing. Before posting question; I searched in google as “Difference between virtual and logical” but I couldn’t found the answer.
Please quote your comments.
Thanks & Kind Regards
Girish Sharma

Girish,
I wont say that I am correcting you as this is like that half glass full/empty thing.May be what I see is half empty , you would see the same as half full.
Well now coming to the explanation.I am saying honestly , I got more confused after reading your definitions.What do you mean by saing that tablespace is not virtual.I see it as purely virtual.We don't say it as virtual tablespace or logical tablespace but it is actualy logical/virtual, having no existance but just the definition right?
How can you say that the size of virtual is larger than logcial?The size of tablespace is actualy the sum total of size of datafiles.So it actualy becomes very larger right?Much larger than JVM which is of few megs only.
The point 3 totally knocked me out.I have no idea what you said.
Ok I tell you this.Just remember the definition that Hans gave already.If you ask me than its the best definition that we can have. Just remember this and if some one asks you more further than give them your point 3 definition and tell them understand this ;-).Please don'tmind I am just kidding. Its just semantics.Don't get lost into it.You will find many people using both the terms interchangibly. So its ok.I shall stick with Hans's defintion,simple and concise.There are lot more other topics to dig upon in oracle.I can mail you lots of them.Spend time on those.Don't think that I am demotivating you.I understand you asked only because you have a doubt.But we got a good resolution of it and beyond that, its not of much use to dig it atleast not in the technial terms.
Cheers
Aman....
PS:Are you on oraclecommunity.net?

Difference between Truncate and Deete .

Hi All,
Can any one pls tell me,
what is the main difference between Truncate and Delete.
Thanks in advance ,
Sanjeev.

Deletes perform normal DML,it take locks on rows, they generate redo and they require segments in the UNDO tablespace.
If a mistake is made a rollback can be issued to restore the records prior to a commit.
Truncates are DDL. A truncate moves the High Water Mark of the table back to zero so all extents bar the initial are de-allocated from the table

Difference between poh and pov in module pool programming

hi all,
                   pls tell me difference between poh and pov and how i check validation in screen

Hi,
POV gives you F4 help.
like:
You can call dialog modules in the POV event using the event keyword PROCESS ON VALUE-REQUEST.
PROCESS ON VALUE-REQUEST.
FIELD f MODULE mod.
After the PROCESS ON VALUE-REQUEST statement, you can only use the MODULE statement together with the FIELD statement. When the user chooses F4 for a field f, the system calls the module mod belonging to the FIELD statement. If there is more than one FIELD statement for the same field f, only the first is executed. The module mod is defined in the ABAP program like a normal PAI module. However, the contents of the screen field f are not available, since it is not transported by the FIELD statement during the PROCESS ON HELP-REQUEST event. You can now program your own value lists in the module. However, this procedure is only recommended if it really is not possible to use a search help. Defining search helps is much easier than PROCESS ON VALUE-REQUEST, since the system takes over some of the standard operations, such as getting field contents from the screen. It also ensures that the F4 help has a uniform look and feel throughout the system. Furthermore, it means that you do not have to reassign input help to fields on each screen.
Despite the introduction of search helps (and search help exits), there are still cases in which you need to use parts of the standard F4 functions directly. In this case, there are some standard function modules that you can use in the POV event. They support search helps, as well as all other kinds of input help, and are responsible for data transport between the screen and the input help. These alll have the prefix F4IF_. The most important are:
·        F4IF_FIELD_VALUE_REQUEST
Calls the input help of the ABAP Dictionary dynamically. You can pass the component names of a structure or database table of the ABAP Dictionary to the function module in the import parameters TABNAME and FIELDNAME. The function module starts the ABAP Dictionary input help for this component. All of the relevant screen fields are read. If you specify the import parameters DYNPPROG, DYNPNR, and DYNPROFIELD, the users selection is returned to the corresponding field on the screen. If you specify the table parameter RETURN_TAB, the selection is returned into the table instead.
·        F4IF_INT_TABLE_VALUE_REQUEST
This function module displays a value list that you created in an ABAP program. The self-programmed value list is passed to the function module as the table parameter VALUE_TAB. If you specify the import parameters DYNPPROG, DYNPNR, and DYNPROFIELD, the users selection is returned to the corresponding field on the screen. If you specify the table parameter RETURN_TAB, the selection is returned into the table instead.
There are also two function modules - DYNP_VALUES_READ and DYNP_VALUES_UPDATE - that can read the values of screen fields and return values to them during the POV event. For further information, refer to the relevant function module documentation.
Input help in dialog modules
REPORT demo_dynpro_f4_help_module.
TYPES: BEGIN OF values,
         carrid TYPE spfli-carrid,
         connid TYPE spfli-connid,
       END OF values.
DATA: carrier(3) TYPE c,
      connection(4) TYPE c.
DATA: progname TYPE sy-repid,
      dynnum   TYPE sy-dynnr,
      dynpro_values TYPE TABLE OF dynpread,
      field_value LIKE LINE OF dynpro_values,
      values_tab TYPE TABLE OF values.
CALL SCREEN 100.
MODULE init OUTPUT.
progname = sy-repid.
dynnum   = sy-dynnr.
CLEAR: field_value, dynpro_values.
field_value-fieldname = 'CARRIER'.
APPEND field_value TO dynpro_values.
ENDMODULE.
MODULE cancel INPUT.
LEAVE PROGRAM.
ENDMODULE.
MODULE value_carrier INPUT.
CALL FUNCTION 'F4IF_FIELD_VALUE_REQUEST'
       EXPORTING
            tabname     = 'DEMOF4HELP'
            fieldname   = 'CARRIER1'
            dynpprog    = progname
            dynpnr      = dynnum
            dynprofield = 'CARRIER'.
ENDMODULE.
MODULE value_connection INPUT.
CALL FUNCTION 'DYNP_VALUES_READ'
       EXPORTING
            dyname             = progname
            dynumb             = dynnum
            translate_to_upper = 'X'
       TABLES
            dynpfields         = dynpro_values.
READ TABLE dynpro_values INDEX 1 INTO field_value.
SELECT carrid connid
    FROM spfli
    INTO CORRESPONDING FIELDS OF TABLE values_tab
    WHERE carrid = field_value-fieldvalue.
CALL FUNCTION 'F4IF_INT_TABLE_VALUE_REQUEST'
       EXPORTING
            retfield    = 'CONNID'
            dynpprog    = progname
            dynpnr      = dynnum
            dynprofield = 'CONNECTION'
            value_org   = 'S'
       TABLES
            value_tab   = values_tab.
ENDMODULE.
*POH gives you F1 documentation:*
like:
If data element supplement documentation is insufficient for your requirements, or you want to display help for program fields that you have not copied from the ABAP Dictionary, you can call dialog modules in the POH event:
PROCESS ON HELP-REQUEST.
FIELD is defined in the ABAP program like a normal PAI module. The processing logic of the module must ensure that adequate help is displayed for the field in question. Instead of calling an extra screen with text fields, you should use one of the following function modules to display a suitable SAPscript document:
HELP_OBJECT_SHOW_FOR_FIELD
This function module displays the data element documentation for components of any structure or database table from the ABAP Dictionary. You pass the name of the component and structure or table to the import parameters FIELD and TABLE.
HELP_OBJECT_SHOW
Use this function module to display any SAPscript document. You must pass the document class (for example, TX for general texts, DE for data element documentation) and the name of the document to the import parameters DOKCLASS and DOKNAME. For technical reasons, you must also pass an empty internal table with the line type TLINE to the tables parameter of the function module.
For further information about how to create SAPscript documents, refer to the Documentation of System Objects documentation.
Field help on screens.
REPORT DEMO_DYNPRO_F1_HELP.
DATA: TEXT(30),
       VAR(4),
       INT TYPE I,
       LINKS TYPE TABLE OF TLINE,
       FIELD3, FIELD4.
TABLES DEMOF1HELP.
TEXT = TEXT-001.
CALL SCREEN 100.
MODULE CANCEL INPUT.
LEAVE PROGRAM.
ENDMODULE.
MODULE F1_HELP_FIELD2 INPUT.
INT = INT + 1.
CASE INT.
    WHEN 1.
    VAR = '0100'.
    WHEN 2.
    VAR = '0200'.
    INT = 0.
ENDCASE.
ENDMODULE.
MODULE F1_HELP_FIELD3 INPUT.
CALL FUNCTION 'HELP_OBJECT_SHOW_FOR_FIELD'
       EXPORTING
            DOKLANGU                      = SY-LANGU
            DOKTITLE                      = TEXT-002
            CALLED_FOR_TAB                = 'DEMOF1HELP'
            CALLED_FOR_FIELD              = 'FIELD1'.
ENDMODULE.
MODULE F1_HELP_FIELD4 INPUT.
CALL FUNCTION 'HELP_OBJECT_SHOW'
       EXPORTING
            DOKCLASS                      = 'TX'
            DOKLANGU                      = SY-LANGU
            DOKNAME                       = 'DEMO_FOR_F1_HELP'
            DOKTITLE                      = TEXT-003
       TABLES
            LINKS                         = LINKS.
ENDMODULE.
Regards,
Renjith Michael

Graph axes assignment: performance difference between ATTR_ACTIVE_XAXIS and ATTR_PLOT_XAXIS

Hi,
I am using a xy graph with both x axes and both y axes. There are two possibilities when adding a new plot:
1) PlotXY and SetPlotAttribute ( , , , ATTR_PLOT_XAXIS, );
2) SetCtrlAttribute ( , , ATTR_ACTIVE_XAXIS, ) and PlotXY
I tend to prefer the second method because I would assume it to be slightly faster, but what do the experts say?
Thanks!
Solved!
Go to Solution.

Hi Wolfgang,
thank you for your interesting question.
First of all I want to say, that generally spoken, using the command "SetCtrlAttribute"is the best way to handle with your elements. I would suggest using this command when ever it is possible.
Now, to your question regarding the performance difference between "SetCtrlAttribute" and "SetPlotAttribute".
I think the performance difference occures, because in the background of the "SetPlotAttribute" command, another function called "ProcessDrawEvents" is executed. This event refreshes your plot again and again in the function whereas in the "SetCtrlAttribute" the refreshing is done once after the function has been finished. This might be a possible reason.
For example you have a progress bar which shows you the progress of installing a driver:
"SetPlotAttribute" would show you the progress bar moving step by step until installing the driver is done.
"SetCtrlAttribute" would just show you an empty bar at the start and a full progress bar when the installing process is done.
I think it is like that but I can't tell you 100%, therefore I would need to ask our developers.
If you want, i can forward the question to them, this might need some times. Also, then I would need to know which version of CVI you are using.
Please let me now if you want me to forward your question.
Have a nice day,
Abduelkerim
Sales
NI Germany

Difference between open_form and start_form

difference between open_form and start_form?

hi,
Any driver program must contain Open_Form, Close_Form and Write_Form. Other function modules are optional.
OPEN_FORM: This function module opens layout set printing. One must call this function module before he uses any of other layout set function modules like Write_Form, Start_Form, Control_Form etc., You need specify a layout set name in the export parameters of this function module. If nothing is passed to Open_Form then one should use Start_Form function module to open layout set before starting the output. The layout set opened by Open_Form should be closed by Close_Form function module, other wise output doesnt appear. We can use any number of Open_Form, Close_Form functions in one single program. But Close_Form must be there for every Open_Form in the program.
Some of the important export parameters we have to pass to Open_Form function module.
Form: Enter the Layout set name here, which then controls the output formatting. If nothing is specified then we must use Start_Form for opening layout set.
Language: Layout sets are Language dependent. Enter the desired language here. If the entered layout set is not in that language, then the function tries to open the Form entered in its original language. The default value is SY-LANGU.
Device: SAP Script can format a text on different device types. The device can be PRINTER or TELEX, TELEFAX, ABAP and SCREEN.
Dialog: Use parameter DIALOG to determine whether to display a dialog box before printing, in which the user can set several spool parameters for print formatting. Possible values: SPACE displays no print parameter screen. 'X' display print parameter screen. Default value: 'X'
Options: Use parameter OPTIONS to set several options for print formatting. The parameter has the structure ITCPO. The user can change some of the defined settings on the print control screen. The default value for Options is . We will discuss about ITCPO structure in detail later.
Other Export, Import and Exceptions are self-explanatory.
Start_Form: In-between the function modules OPEN_FORM and CLOSE_FORM, we can use different layout sets. This allows us to combine several different layout sets into one print output. However, we can combine only those layout sets that have the same page format. To switch layout sets, use the function module START_FORM. If another layout set is still open, we must close it first using END_FORM. If we specify no layout set name when calling START_FORM, the system restarts the last open layout set. If after OPEN_FORM no layout set was activated yet, the system leaves the function module with the exception UNUSED. Some of the important export parameters for this function module are
Form: The parameter contains the name of the layout set you want to use for printing. If you specify no layout set here, the system restarts the last active layout set.
Language: Layout sets are language-dependent. Enter the desired language here. If the layout set does not exist in this language, the system tries to call the layout set in its original language. If the parameter LANGUAGE is empty, the system uses the language of the last active layout set.
Startpage: Usually, SAP script starts with the page specified as start page in the layout set definition. If we want to start output with another layout set page, enter the name of the desired layout set page here. If the desired page is not defined, the system uses the start page defined in the layout set.
Program: To replace program symbols, SAP script must know which active program contains the work areas for the values to be passed. If we omit the parameter, the system searches for the field values in the program that was specified in the parameter OPTIONS (field TDPROGRAM) of OPEN_FORM. If we enter a program name, the system replaces the program symbols with the values from this program up to the next END_FORM.
Exceptions and other Export, Import parameters are self-explanatory.
Regards
Kiran Sure

What is the difference between tkprof and explainplan

Hi,
what is the difference between tkprof and explainplan.

Execution Plans and the EXPLAIN PLAN Statement
Before the database server can execute a SQL statement, Oracle must first parse the statement and develop an execution plan. The execution plan is a task list of sorts that decomposes a potentially complex SQL operation into a series of basic data access operations. For example, a query against the dept table might have an execution plan that consists of an index lookup on the deptno index, followed by a table access by ROWID.
The EXPLAIN PLAN statement allows you to submit a SQL statement to Oracle and have the database prepare the execution plan for the statement without actually executing it. The execution plan is made available to you in the form of rows inserted into a special table called a plan table. You may query the rows in the plan table using ordinary SELECT statements in order to see the steps of the execution plan for the statement you explained. You may keep multiple execution plans in the plan table by assigning each a unique statement_id. Or you may choose to delete the rows from the plan table after you are finished looking at the execution plan. You can also roll back an EXPLAIN PLAN statement in order to remove the execution plan from the plan table.
The EXPLAIN PLAN statement runs very quickly, even if the statement being explained is a query that might run for hours. This is because the statement is simply parsed and its execution plan saved into the plan table. The actual statement is never executed by EXPLAIN PLAN. Along these same lines, if the statement being explained includes bind variables, the variables never need to actually be bound. The values that would be bound are not relevant since the statement is not actually executed.
You don’t need any special system privileges in order to use the EXPLAIN PLAN statement. However, you do need to have INSERT privileges on the plan table, and you must have sufficient privileges to execute the statement you are trying to explain. The one difference is that in order to explain a statement that involves views, you must have privileges on all of the tables that make up the view. If you don’t, you’ll get an “ORA-01039: insufficient privileges on underlying objects of the view” error.
The columns that make up the plan table are as follows:
Name Null? Type
STATEMENT_ID VARCHAR2(30)
TIMESTAMP DATE
REMARKS VARCHAR2(80)
OPERATION VARCHAR2(30)
OPTIONS VARCHAR2(30)
OBJECT_NODE VARCHAR2(128)
OBJECT_OWNER VARCHAR2(30)
OBJECT_NAME VARCHAR2(30)
OBJECT_INSTANCE NUMBER(38)
OBJECT_TYPE VARCHAR2(30)
OPTIMIZER VARCHAR2(255)
SEARCH_COLUMNS NUMBER
ID NUMBER(38)
PARENT_ID NUMBER(38)
POSITION NUMBER(38)
COST NUMBER(38)
CARDINALITY NUMBER(38)
BYTES NUMBER(38)
OTHER_TAG VARCHAR2(255)
PARTITION_START VARCHAR2(255)
PARTITION_STOP VARCHAR2(255)
PARTITION_ID NUMBER(38)
OTHER LONG
DISTRIBUTION VARCHAR2(30)
There are other ways to view execution plans besides issuing the EXPLAIN PLAN statement and querying the plan table. SQL*Plus can automatically display an execution plan after each statement is executed. Also, there are many GUI tools available that allow you to click on a SQL statement in the shared pool and view its execution plan. In addition, TKPROF can optionally include execution plans in its reports as well.
Trace Files and the TKPROF Utility
TKPROF is a utility that you invoke at the operating system level in order to analyze SQL trace files and generate reports that present the trace information in a readable form. Although the details of how you invoke TKPROF vary from one platform to the next, Oracle Corporation provides TKPROF with all releases of the database and the basic functionality is the same on all platforms.
The term trace file may be a bit confusing. More recent releases of the database offer a product called Oracle Trace Collection Services. Also, Net8 is capable of generating trace files. SQL trace files are entirely different. SQL trace is a facility that you enable or disable for individual database sessions or for the entire instance as a whole. When SQL trace is enabled for a database session, the Oracle server process handling that session writes detailed information about all database calls and operations to a trace file. Special database events may be set in order to cause Oracle to write even more specific information—such as the values of bind variables—into the trace file.
SQL trace files are text files that, strictly speaking, are human readable. However, they are extremely verbose, repetitive, and cryptic. For example, if an application opens a cursor and fetches 1000 rows from the cursor one row at a time, there will be over 1000 separate entries in the trace file.
TKPROF is a program that you invoke at the operating system command prompt in order to reformat the trace file into a format that is much easier to comprehend. Each SQL statement is displayed in the report, along with counts of how many times it was parsed, executed, and fetched. CPU time, elapsed time, logical reads, physical reads, and rows processed are also reported, along with information about recursion level and misses in the library cache. TKPROF can also optionally include the execution plan for each SQL statement in the report, along with counts of how many rows were processed at each step of the execution plan.
The SQL statements can be listed in a TKPROF report in the order of how much resource they used, if desired. Also, recursive SQL statements issued by the SYS user to manage the data dictionary can be included or excluded, and TKPROF can write SQL statements from the traced session into a spool file.
How EXPLAIN PLAN and TKPROF Aid in the Application Tuning Process
EXPLAIN PLAN and TKPROF are valuable tools in the tuning process. Tuning at the application level typically yields the most dramatic results, and these two tools can help with the tuning in many different ways.
EXPLAIN PLAN and TKPROF allow you to proactively tune an application while it is in development. It is relatively easy to enable SQL trace, run an application in a test environment, run TKPROF on the trace file, and review the output to determine if application or schema changes are called for. EXPLAIN PLAN is handy for evaluating individual SQL statements.
By reviewing execution plans, you can also validate the scalability of an application. If the database operations are dependent upon full table scans of tables that could grow quite large, then there may be scalability problems ahead. On the other hand, if large tables are accessed via selective indexes, then scalability may not be a problem.
EXPLAIN PLAN and TKPROF may also be used in an existing production environment in order to zero in on resource intensive operations and get insights into how the code may be optimized. TKPROF can further be used to quantify the resources required by specific database operations or application functions.
EXPLAIN PLAN is also handy for estimating resource requirements in advance. Suppose you have an ad hoc reporting request against a very large database. Running queries through EXPLAIN PLAN will let you determine in advance if the queries are feasible or if they will be resource intensive and will take unacceptably long to run.

Differences between awt and swing

Ive written the following code, however Ive implemented the gui in awt rather then swing. Ive been told it hs too be in swing. What is the difference between swing and awt what will I need to change in my program so that its done using swing rather then the awt? Heres the code:
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class: pp
// This class drives the customer manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends Frame implements ActionListener
// Container of customer objects
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private Button delete;
private Button update;
// Default constructor.
public pp ()
// Assign "Paper Round Manager" to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save customers and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem.
Label l = new Label ();
add ("North", l);
// Place the names component in the center part of the
// frame window.
add ("Center", names);
// Create a panel object to hold four buttons.
Panel p = new Panel ();
Button b;
// Add an Insert button to the Panel object and register
// the current pp object as a listener for button events.
p.add (b = new Button ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current pp object as a listener for button events.
p.add (delete = new Button ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one customer to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current pp object as a listener for button events.
p.add (update = new Button ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one customer to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current customer object as a listener for button events.
p.add (b = new Button ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
add ("South", p);
// Set the background of the frame window container to
// lightGray
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setSize (400, 200);
// Allow the user to resize the frame window.
setResizable (true);
// Load all contacts.
loadCustomers ();
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new pp object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected contact item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the contact item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new customer.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Contact object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.name + ", " + temp.publication);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all contacts from contacts.dat into the contacts
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("Customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.round = dis.readUTF ();
temp.address = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.name + ", " + temp.publication);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first contact item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all Customer objects from the customer Vector object
// to customer.dat. The number of customerss are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.round);
dos.writeUTF (temp.address);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the customer object (from the
// customers Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.round,
temp.address,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.name + ", " + temp.publication,
index);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);

Ive doen pretty much what you said burt now my program isnt working at all. The window comes up but instead of doing something when you click the button it just throws shit loads of exceptions. Heres my abridged code
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class:PP
// This class drives the Paper Round manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends JFrame implements ActionListener
// Container of customer objects (one object per customer)
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private JButton delete;
private JButton update;
// Default constructor.
public pp ()
// Assign Contact Manager to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save contacts and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem. (One thing that you'll come to realize as
// you work with the AWT is that there are lots of bugs.)
JLabel l = new JLabel ();
getContentPane().add ("North", l);
// Place the names component in the center part of the
// frame window.
getContentPane().add ("Center", names);
// Create a panel object to hold four buttons.
JPanel p = new JPanel ();
JButton b;
// Add an Insert button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current cm object as a listener for button events.
p.add (delete = new JButton ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one contact to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current cm object as a listener for button events.
p.add (update = new JButton ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one contact to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
getContentPane().add ("South", p);
// Set the background of the frame window container to
// lightGray (to give a pleasing effect).
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setBounds (50, 100, 400, 200);
// Do not allow the user to resize the frame window.
loadCustomers ();
// Load all contacts.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new cm object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the customer item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new contact.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Customer object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String
(def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.publication + ", " + temp.address);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all customers from customers.dat into the customers
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.address = dis.readUTF ();
temp.round = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.publication + ", " + temp.address);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all customer objects from the contacts Vector object
// to customers.dat. The number of contacts are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.address);
dos.writeUTF (temp.round);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the Customer object (from the
// customer Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.address,
temp.round,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.publication + ", " + temp.address,
index);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);
// ========================================================
// Class: Customer
// This class describes the contents of a business customer.
// ========================================================
class Customer
public String name;
public String publication;
public String address;
public String round;
public String phone;
// ==========================================================
// Class: DataEntryForm
// This class provides a data entry form for entering customer
// information.
// ==========================================================
class DataEntryForm extends JDialog implements ActionListener
// bOk is a boolean flag. When true, it indicates that
// the Ok button was pressed to terminate the dialog box
// (as opposed to the Cancel button).
public boolean bOk;
// The following components hold the text that the user
// entered into the visible text fields.
public JTextField name;
public JTextField publication;
public JTextField address;
public JTextField round;
public JTextField phone;
public void actionPerformed (ActionEvent e)
// If the user pressed the Ok button, indicate this
// by assigning true to bOk.
if (e.getActionCommand ().equals ("Ok"))
bOk = true;
// Destroy the dialog box and return to the point
// just after the creation of the DataEntryForm object.
dispose ();
public DataEntryForm (JFrame parent, String title)
// Call the other constructor. The current constructor
// is used for insert operations. The other constructor
// is used for update operations.
this (parent, title, "", "", "", "", "");
public DataEntryForm (JFrame parent, String title,
String name, String publication,
String address, String round,
String phone)
// Initialize the superclass layer.
super (parent, title, true);
// Choose a grid bag layout so that components can be more
// accurately positioned. (It looks nicer.)
setLayout (new GridBagLayout ());
// Add appropriate first name, last name, phone, fax, and
// email components to the current DataEntryForm container.
// (Remember, DataEntryForm is a subclass of Dialog.
// Dialog is a container. Therefore, DataEntryForm
// inherits the ability to be a container.)
addComponent (this, new JLabel ("Name: "), 0, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.name = new JTextField (15);
addComponent (this, this.name, 1, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.name.setText (name);
addComponent (this, new JLabel ("Publications: "), 0, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.publication = new JTextField (15);
addComponent (this, this.publication, 1, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.publication.setText (publication);
addComponent (this, new JLabel ("Address "), 0, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.address = new JTextField (15);
addComponent (this, this.address, 1, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.address.setText (address);
addComponent (this, new JLabel ("Round No "), 0, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.round = new JTextField (15);
addComponent (this, this.round, 1, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.round.setText (round);
addComponent (this, new JLabel ("Phone Number "), 0, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.phone = new JTextField (15);
addComponent (this, this.phone, 1, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.phone.setText (phone);
addComponent (this, new JLabel (""), 0, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
addComponent (this, new JLabel (""), 1, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
JButton b;
// Add an Ok button to this container.
addComponent (this, b = new JButton ("Ok"), 0, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Add a Cancel button to this container.
addComponent (this, b = new JButton ("Cancel"), 1, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Set the size of the dialog window to 250 pixels
// horizontally by 200 pixels vertically.
setSize (250, 200);
// Do not allow users to resize the dialog window.
setResizable (false);
// Make sure that the dialog window is visible.
setVisible (true);
private void addComponent (Container con, Component com,
int gridx, int gridy,
int gridw, int gridh, int fill,
int anchor)
// Get the current layout manager. It is assumed to
// be a GridBagLayout object.
LayoutManager lm = con.getLayout ();
// Create a GridBagConstraints object to make it
// possible to customize component positioning.
GridBagConstraints gbc = new GridBagConstraints ();
// Assign the x and y grid positions.
gbc.gridx = gridx;
gbc.gridy = gridy;
// Assign the number of grid blocks horizontally and
// vertically that are occupied by the component.
gbc.gridwidth = gridw;
gbc.gridheight = gridh;
// Specify the component's resize policy (fill) and
// the direction in which the component is positioned
// when its size is smaller than available space (anchor).
gbc.fill = fill;
gbc.anchor = anchor;
// Set the new constraints that the grid bag layout
// manager will use.
((GridBagLayout) lm).setConstraints (com, gbc);
// Add the component to the container.
con.add (com);
// ===========================================================
// Class: MsgBox
// This class displays a message box to the user. The message
// is usually an error message. The user must press the Ok
// button to terminate the message box.
// ===========================================================
class MsgBox extends JDialog implements ActionListener
public void actionPerformed (ActionEvent e)
// Terminate the dialog box in response to the user
// pressing the Ok button.
dispose ();
public MsgBox (JFrame parent, String title, String msg)
// Initialize the superclass layer.
super (parent, title, true);
// Store the msg argument in a Label object and add
// this object to the center part of the dialog window.
JLabel l = new JLabel (msg);
add ("Center", l);
// Create a Button object and add it to the south part
// of the dialog window.
JButton b = new JButton ("Ok");
add ("South", b);
// Make the current object a listener to events that
// occur as a result of the user pressing the Ok
// button.
b.addActionListener (this);
// Make sure that the Ok button has the focus.
b.requestFocus ();
// Do not allow users to resize the dialog window.
setResizable (false);
// Allow the layout manager to choose an appropriate
// size for the dialog window.
pack ();
// Make sure that the dialog window is visible.
setVisible (true);
}

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