How to understand the logic of existing code

Hi friends
I am new to java and I got the job in a company. Now they give me task to complete which use existing api developed by sr developers. Now my question is how can i understant such a large project with almost 200000 line of code.
It is web based project and using jsp and java mainly
Can anybody suggest me how can I understand it so that I can use this api and develop new code
Thanks

Use the javadoc tool to create documentation for the code.
Read the resulting documentation. Even if the senior developers didn't add any Javadoc comments (in which case, they're morons, despite being "senior"), it would be helpful just to see what the methods and classes are. In particular, look at the interfaces in the code. In well-crafted code, you get a good bird's-eye-view of the structure by looking at the interfaces and the relationships between them (in my opinion).
It's possible that the code is simply crap, in which case, you're in for a long hard slog my friend.

Similar Messages

How do u find logical datanase exist for ur program requirement?

How do u find logical datanase exist for ur program requirement?

Hi,
The transaction Code SE36 is where you can find all the Logical Database that exist in the SAP system. You can find the existing logical database that exist and can use which ever that suits your needs.
Logical Databases are mostly used in HR ABAP and in HCM Reports.
Thanks,
Samantak.
<b>Rewards points for useful answers.</b>

How to create the logical file name

Hi All,
    I have requirement where i need to post the Inventory Management data. for this i need to execute std. program RM07MMBL which is having logical file name in the selection screen. but i have placed my input file in application server.
   Can any one tell how to create the Logical filename which refers the physical path. I also tried <b>t-code SF01 & Table - FILENAMEC</b>I and found that we need to add an entry in this table but i really dont know how we have to do since this table cannot be maintained in SM30 also..
Help Me.
Thanks in Advance!...
Regards,
Ramkumar

Hi Ram,
Try using FILE transaction code...
Follow these steps to create:::
Double click on Logical file Path Definition
Click on New Entries,
Give Logical file Path name as Z_LOGICAL PATH and save it
now choose this path and double click on Assignemt of Physical path to Logical path
double click on the OS name
Give some description and give some Physical path name from AL11 transaction and save it
Now Double click on Logical File Name Definition,
Click on New Entries,
Give some logical file name: Z_LOGICAL_FILENAME
Physical file: test
Data Format: BIN
Logical Path: Z_LOGICAL PATH
Hope this helps
Regards,
Phani
Message was edited by:
        Sivapuram Phani Kumar

How to delete the logical lines in JTextArea

Hi all,
Now that I know how to find the logical line count in JTextArea as
I found the following in the forum.
public static int getLineCount (JTextArea _textArea)
boolean lineWrapHolder = _textArea.getLineWrap();
_textArea.setLineWrap(false);
double height = _textArea.getPreferredSize().getHeight();
_textArea.setLineWrap(lineWrapHolder);
double rowSize = height/_textArea.getLineCount();
return (int) (_textArea.getPreferredSize().getHeight() / rowSize);
I want to delete the 4th line to the last line and append ... at the 4th, if the getLineCount exceeds 3. Does any body know how to do so?
The intention is for the multiline tooltip as I just want to show
the first three logical line and ... if the string is too long.
Thanks
Pin

The code looks good to me. The only thought I have is that the y coordinate for the rowThree point is wrong and is referencing row four.
I've been playing around with using a JTextArea as a renderer for a JTable. I have it working so that "..." appear when the text exceeds 2 rows. Try clicking on "B" in the letter column and then the update cell button a few times to add text. My code is slightly different than yours.
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;
public class TestTable extends JFrame
     private final static String LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
     JTable table;
     Vector row;
     public TestTable()
          Object[][] data = { {"1", "A"}, {"2", "B"}, {"3", "C"} };
          String[] columnNames = {"Number","Letter"};
          DefaultTableModel model = new DefaultTableModel(data, columnNames);
          table = new JTable(model)
               public String getToolTipText( MouseEvent e )
                    int row = rowAtPoint( e.getPoint() );
                    int column = columnAtPoint( e.getPoint() );
                    if (row == 0)
                         return null;
                    else
                         return row + " : " + column;
          table.setRowSelectionInterval(0, 0);
          table.setColumnSelectionInterval(0, 0);
          table.setRowHeight(0,34);
          table.setRowHeight(1,34);
          table.setRowHeight(2,34);
          table.setDefaultRenderer(Object.class, new TextAreaRenderer(2));
          JScrollPane scrollPane = new JScrollPane( table );
          getContentPane().add( scrollPane );
          JPanel buttonPanel = new JPanel();
          getContentPane().add( buttonPanel, BorderLayout.SOUTH );
          JButton button2 = new JButton( "Update Cell" );
          buttonPanel.add( button2 );
          button2.addActionListener( new ActionListener()
               public void actionPerformed(ActionEvent e)
                    int row = table.getSelectedRow();
                    int column = table.getSelectedColumn();
                    String value = (String)table.getValueAt(row, column);
                    value += value;
                    table.setValueAt( value, row, column );
                    DefaultTableModel model = (DefaultTableModel)table.getModel();
                    model.fireTableCellUpdated(row, column);
                    table.requestFocus();
     public static void main(String[] args)
          TestTable frame = new TestTable();
          frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
          frame.pack();
          frame.setVisible(true);
     private class TextAreaRenderer extends JTextArea implements TableCellRenderer
          public TextAreaRenderer(int displayRows)
               setRows(displayRows);
               setLineWrap( true );
          public Component getTableCellRendererComponent(JTable table,
                                         Object value,
                                         boolean isSelected,
                                         boolean hasFocus,
                                         int row,
                                         int column)
               setText( value.toString() );
               Dimension d = getPreferredSize();
               int maximumHeight = getRows() * getRowHeight();
               if (d.height > maximumHeight)
                    setSize(d);
                    int offset = viewToModel( new Point(d.width, maximumHeight - 1) );
                    replaceRange( "...", offset-3, getDocument().getLength() );
               return this;
}

Could you please help me understand the logic behind certain things in OSX?

Ok, so I try to be an open-minded guy, and I bear no particular allegiance to either OS. I own a Sony TZ and a Mac mini, and my wife has a MacBook Pro. I use both Oses.
There are certain things I have trouble understanding in th Mac OS, so what I'd really like to understand the logic behind certain design decisions in the OS, and why these might be better ways of accomplishing things. I know how to get around all of the things I mention, so I'm not looking for instructions; rather I'm looking for well-thought out explanations for why these features are the way they are.
*1. Programs don't quit when you close the window.*
- This totally puzzles me. Why design it so that program windows are independent are from the running program itself? There must be a reason, cold someone explain how this is more efficient? To me, it's simpler to click an X on the window you are working on to completely shut down a program, rather than to either mouse through menus to select quit, or be obligated to using Command Q keyboard shortcut.
*2. Menu bars are on the desktop.*
- Related to the first point, why make the main thing framing your desktop be something which is always changing depending on the program? Why have file menus outside the main window of the program. Having the menu bar on the desktop then necessitates an additional area, the dock, which has to be used as a launch bar and to tell you what programs are currently running. That obligates you to having 3 different areas of screen: 1 for program menus, 1 for running programs, and the program window itself. This seems very inefficient to me. Not to mention all the messy-looking floating palettes all over the place, again because everything is separated and not nicely contained in a single program window.
- Really, having a changing menu bar that frames the desktop isn't even consistent wth the whole desktop metaphor, which is that you place things on a desktop, like programs, files, etc. Are you changing the whole desk everytime you load a new program, yet the wallpaper stays the same? Doesn't seem to be logically consistent to me.
*3. No delete key.*
- This one really gets me. Why make such a commonly used key be a function key (Fn + Backspace)? Why make the user press a secondary key for a major function?
*4. No Cut command.*
- I read something about how Cut doesn't actually make sense when moving files around, but I obviously didn't fully understand it. Why make the user command drag, when you can just do Ctrl X??.
*5. Launching Apps from the Finder.*
- This seems weird to me, that you find and launch applications from the same thing you use to view files. Program icons in the finder are placeholders for the entire program, not files, yet they are found in the file viewer. Again, to me this seems logically mixed. I really dislike scrolling through Finder to look for apps. I know there is Spotlight and the dock (used as a quicklauncher), but these are really just workarounds for a setup which seems inherently illogical. To me at least, a menu of applications make more sense, ie, the start menu.
Anyway, those are all I can think of now, although there are other things aout OSX that don't make sense to me.
Thanks in advance! If I can understand Apple's reasoning and it is convincingly better, that will go a long way towards making me more comfortable with this OS.

1. Programs don't quit when you close the window.
That's really more a matter of what you're used to. It comes down to a programming decision as to what Apple and Microsoft considered to make sense. MS thinks that if there are no open windows, you're done using the app. Apple thinks you aren't necessarily done yet, as others have mentioned. I certainly wouldn't want Photoshop to quit every time I closed the last open image I was working on. Would be nice though if Safari would quit when I close the last open browser window. It's quick to relaunch if you really weren't done with it, so wouldn't be much of a bother to have it shut down with the last window.
2. Menu bars are on the desktop.
Makes way more sense the Microsoft's approach of repeating the same file menu on every open document in a program. How many places do you need to see File, Options and other common menu headings?
2. Menu bars are on the desktop.
Related to number two. The forward app is the only one you can directly work in, so why not have the menu bar change to reflect the choices for that application? When you go back to the previous app you were in, the menu bar changes back. So what loss of functionality is there? It comes back to not having menu bars on every single open window. There's no need or purpose for it.
3. No delete key.
Backspace does the same thing.
4. No Cut command.
Command+X, not Ctrl+X. This is Mac, not Windows. There's also very little need to ever do this from the keyboard. If you're moving files that are on the same drive/partition, then just drag and drop from the target folder window to the source. It's automatically a move. If going from one physical drive or partition to another, it's automatically a copy. Press and hold the Command key during the drag to make it a move.
Besides, you don't really think Windows cuts the entire folder or file contents into RAM, do you? If your computer has 4 GB of RAM, and you cut 12 GB of data, it of course can't possibly fit in the clipboard. All Windows does when you do a cut is visually remove the files and folders from the screen. If the items are going to a location on the same drive/partition, it does the same thing as if you did a drag and drop move. The file table is simply updated to reflect the new file or folder locations. If it's to a different drive/partition, it then performs a copy then delete action, same as OS X.
5. Launching Apps from the Finder.
A program is just as much a file as any other file. It takes up space on the drive. The OS of course knows what to do with it when you double click an app. Same as it knows what to do when you double click a document related to an app. Windows is no different. An .exe file is also just as much a file as a .doc file. The .exe extension tells Windows to try and treat it as a program to load into RAM. It's not just a simple placeholder. The program has to be made up of something.

How to understand the STAD relevant for RFC

Hello performance experts.
I have question about how to understand the STAD relevant for RFC.
I want to know how to calculate the response time of action of "Push save buttion"
which call function module by RFC.
In our system, the screen is created using web dynpro and after push the button,
function module for application will be called.
When I push Save button, 2 STAD line is created.
One is for function code " SAVE" and the other is for "RFC".
Line for "SAVE" include RFC as client, and RFC line has RFC info as server (also client)
I wonder how I should calculate the response time of action"Save" button in following case.
Should I add the 2 response time?
1) 5,867 ms +   5,797 m is collect?
2) 5,867 ms include RFC time, so no need to sum the value and 5,867 ms is collect??
3) 590 ms +   5,797 ms is collect?
4) Or other calculation is correct ?
1) STAD for function code:
CPU time                     578 ms
RFC+CPIC time              5,280 ms
Total time in workprocs      594 ms
Response time            5,867 ms
Processing time              590 ms
Load time                      1 ms
Wait            5,273 ms
Roll (in+wait) time        5,274 ms
as Client
Number    Connections                              1
           Destinations                             1
           Users                                    1
           Calls                                    2
Time      Calling                              5,280   ms
           Remote execution                    10,527   ms
           Idle                                11,110   ms
Data      Sent                               135,836   Bytes
           Received                               620   Bytes
2) STAD for RFC
CPU time                   1,406 ms
RFC+CPIC time                  9 ms
Total time in workprocs    5,080 ms
Response time            5,797 ms
Processing time            2,132 ms
Load time                     50 ms
Roll (in+wait) time          718 ms
Database request time      2,882 ms
Enqueue time                  16 ms
Roll time
Wait              717 ms
as Client
Number    Connections                              1
                  Destinations                             1
                     Users                                    1
                       Calls                                    4
Time      Calling                                  9   ms
          Remote execution                         1   ms
          Idle                                     0   ms
Data      Sent                                   686   Bytes
             Received                             1,360   Bytes
as Server
Number    Connections                              1
          Destinations                             1
          Users                                    1
          Calls                                    2
Time      Calling                              5,272   ms
          Remote execution                     5,269   ms
          Idle                                        11,118   ms
Data      Sent                                   620   Bytes
          Received                           135,760   Bytes
Thanks for your cooperation in advance.
Keiichiro

Hi Keiichiro,
I wonder how I should calculate the response time of action"Save" button in following case.
Should I add the 2 response time?
1) 5,867 ms +   5,797 m is collect?
2) 5,867 ms include RFC time, so no need to sum the value and 5,867 ms is collect??
3) 590 ms +   5,797 ms is collect?
4) Or other calculation is correct ?
It depends of what you mean with response time of action "Save" button.
If you mean ALL time, the value is 5.867 because the local time from save was 594ms, the "external" RFC time was 5280ms.
If you want separete analysis, the 594ms is your option since the 5280ms is in other part...
Also, analysing the other part there's another other part which represents a good part of processing time:
Database request time      2,882 ms
Hope this help youl.
Regards, Fernando Da Ró

How to understand the Xcode?

Through my whole life using computers generally, I have figured out that any software could be well understood by practice, but actually the case here seems much different.
My question is not regarding the interface, structure of the project...etc, I would like to understand the coding itself, where and when every code to be used and how it works, there are lots of codes those can be used in different cases, It is not possible that one person can understand every single tip of the Xcode or any other programming language, but I want to know at least which way should I take (courses, books, tutorial....), I want something that gives the general idea and concept of the things.
I am developing a game now, succeeded in creating some different pages of the game where it take you to the setting, high score...etc with some simple graphics, linked them together using the available options, but to make the game work it needs pages of coding, looking for sample codes is also not practical in my opinion.
I believe that understanding the top used 100 code in my opinion will be sufficient for a beginner.
Thanks

Xcode is the IDE.
Objective-C is the language typically used.
There's lots of getting started stuff at https://developer.apple.com

Help in understanding the logic!

Can anyone help me with the following?
Can anyone explain how the below logic works if it has the following Input values:
Input values:
GLOBAL1_CURR_CODE ='LOC'
DOC_CURR_CODE ='USD'
LOC_CURR_CODE ='USD'
IIF(ISNULL(GLOBAL1_CURR_CODE), NULL,
IIF(GLOBAL1_CURR_CODE = DOC_CURR_CODE, 1.0,
IIF(DOC_CURR_CODE = 'STAT', 1.0,
IIF(GLOBAL1_CURR_CODE = LOC_CURR_CODE, DOC_TO_LOC_EXCH_RATE_VAR,
:LKP.LKP_W_EXCH_RATE(DOC_CURR_CODE, GLOBAL1_CURR_CODE, EXCH_DT,GLOBAL1_RATE_TYPE, DATASOURCE_NUM_ID)))))
I am not able to find the :LKP.LKP_W_EXCH_RATE in either SDE or SIL transformations.
Thanks in advance.
Nikki.

Hi again Nikki, I see you have two Oracle.com user accounts!
This appears to relate to several issues you are having in understanding how global currencies work with the BI Applications. For the benefit of others, related threads are:-
Informatica Logic for Balance_Global1_Amt column in W_GL_BALANCE_F table
Informatica Logic for Balance_Global1_Amt column in W_GL_BALANCE_F table.
Insert records into W_EXCH_RATE_G table
Re: Insert records into W_EXCH_RATE_G table.
Modify SIL_GLBalanceFact to populate Balance_Global1_Amt column
Modify SIL_GLBalanceFact to populate Balance_Global1_Amt column.
With regards to your latest question, I recognise that the SQL you have populated below has been taken from the MPLT_CURCY_CONVERSION_RATES1 mapplet in the SIL_GLBalanceFact mapping.
To understand the logic, you need to understand the SQL used by Informatica, as well as Informatica lookup notation. Going through your example line by line:-
GLOBAL1_CURR_CODE ='LOC'
DOC_CURR_CODE ='USD'
LOC_CURR_CODE ='USD'
IIF(ISNULL(GLOBAL1_CURR_CODE), NULL,
-- So if the GLOBAL1_CURR_CODE is null, then return NULL else...
IIF(GLOBAL1_CURR_CODE = DOC_CURR_CODE, 1.0,
-- if the GLOBAL1_CURR_CODE is equal to the DOC_CURR_CODE then return 1.0 else...
IIF(DOC_CURR_CODE = 'STAT', 1.0,
-- if the DOC_CURR_CODE is equal to 'STAT' (for statistical journals) then return 1.0 else...
IIF(GLOBAL1_CURR_CODE = LOC_CURR_CODE, DOC_TO_LOC_EXCH_RATE_VAR,
-- if the GLOBAL1_CURR_CODE is equal to the LOC_CURR_CODE then return the column DOC_TO_LOC_EXCH_RATE_VAR else...
:LKP.LKP_W_EXCH_RATE(DOC_CURR_CODE, GLOBAL1_CURR_CODE, EXCH_DT,GLOBAL1_RATE_TYPE, DATASOURCE_NUM_ID)))))
-- perform a lookup using the LKP_W_EXCH_RATE transformation (you will see this lookup on it's own in the mapplet; the colon notation above is another way to reference a lookup transformation, instead of using connectors). The five columns in the brackets are used as inputs for the lookup, if a matching record is found in the lookup table then the EXCH_RATE column is returned (check out the LKP_W_EXCH_RATE transformation for the port marked as Output).
Please mark if helpful / correct,
Andy
www.project.eu.com

How 2 Set the logic for report 2 run 1st of everymonth......

Hi Experts,
i ve developd a HR-ABAP report in that Some part of code will Mon-Fri, Excluding Public holidays and sat & sundays...( i.e no public holidays and no sat & sundays)
and some part of should Run on 1st of everymonth.... but 2 parts of code should be in same report..
How can set the logic to run the report respective times....
Thanks in Advance....
sudeer.

you can code this but need some good expertise on fm's , date handling techniques and subroutine call coding.
1.
to make the code run only on 1st of every month
capture the rundate of ur prog .. take value of sy-datum
ex.. 01.xx.yyyy
or date std will be yyyymmdd so check for dd = 01 ..
so per logic first two chars show that its first of any month in any year ..
if yes
execute the logic for the first of every month ..
endif.
2.
where the code needs to be run on mon-fri and not on public holidays / sun / sat ..
first fetch the day based on date .. like mon or tue or wed .. except sat and sun..
second check whether if m-t-w-th-fr if any of them is a holiday or not
u need to check the date in the calender list like tholi thoc and .. to check whether that is a holiday or not ..
coming to sat and sundays .. u need to check the day for date using function modules and build the logic ...
br,
vijay..

How to write the logic for extending Idocs...

Hi,
      Can anybody pls explain how to write the logic for extending IDOCs with an example...
      Good suggestions can be appreciated..
Regards,
Ram

Hi Ram,
Generally the IDoc user exit is called at the following places:
1) When the control record is read.
2) After each and every segment in the data record
3) At the end of the data segment processing.
The IDoc user exit interface generally imports IDOC_DATA (data record internal table) table. Now the data records in the internal table should appear in the same order as maintained while defining IDoc structure (WE30 transaction). For SAP standard segment SAP code will take care of this. For extended segment you will have to take care of this aspect by appending the Z-segment in the IDOC_DATA table.
You can do this by:
         looping at IDOC_DATA table:
             - Do a case-endcase fo IDOC_DATA-SEGNAM (This stores the segment
               structure as per the hierarchy).
             - Within the case for "Z-segment" you can write the logic for appending
               the Z-segment to IDOC_DATA-SDATA.
Hope this gives some clue.
Regards,
Gajendra.

How to find the list of existing tables in a schema using DB link?

Hi
I know how to find the list of existing tables in a schema using the following query
SQL> select * from tab;
but, how to list the tables using a DB link?
For Example
SQL> select * from tab@dblink_name;
why this doesn't work?
Pl advice me
Thanks
Reddy.

ORA-02019: connection description for remote database not foundHave you used this database link successfully for some other queries?
The error posted seems to indicate that the DB Link is not functional at all. Has it worked for any other type of DML operation or is this the first time you ever tried to use the link?

How to change the lenth of existing field in sap standard table

Hi all,
can anybody help,my requirement is, how to change the length of existing field in sap standard table....
thanks in advance..

Which field are you thinking of in particular? Are you wanting to increase or decrease the length?
Some fields are used so extensively that a change to their length will mean adjusting many tables, some of them potentially very large, and hence taking a long time to adjust.
Some standard SAP programs expect certain fields to be of specific lengths and won't work if the length is changed.
Some screens could cease to work.
If you decrease length, then you could lose data.
matt

How to change the text Transport id code in sus

Hi,
How to change the text Transport id code in sus while creating ASN
Please advise.
Regards,
manu

SE80---> BSP APPLICATION with SRMSUS ---> views -->asn > detail_edit.inc.->
On the right hand side in the details ---> search for
BBP_SUS_UI/ASN_TRANSPORT_IDENTIFICATION
replace the above with the following
BBP_SUS_UI/INVOICE_DOCUMENT_NUMBER
BBP_SUS_UI/INVOICE.
there is no entry available for invoice number , only the above two are available.
save the changes
activate the changes
REWARD POINTS IF USEFULL

How to execute the logical database.

how to execute the logical database.

There are two ways of using a logical database - either by linking it with the executable program(specify the LDB name in the program attributes) or by using the function module LDB_PROCESS.
1.Data read by the logical database is passed back to the program using the interface work areas.Use GET statements in the report.
GET events are implemented internally as FORM routines.
2.If you call the logical database using the above function module, the selection screen of LDB is not displayed.It uses special subroutines called callback routines, which are called by the function module and filled with the required data.
Please refer the following link for more details.
http://help.sap.com/saphelp_nw70/helpdata/en/9f/db9b5e35c111d1829f0000e829fbfe/frameset.htm

[q] how to understand the 'order' of a list?

hi,everyone
there's a test program:
import java.util.*;
public class testList
void test()
LinkedList ll= new LinkedList();
ll.add("3");
ll.add("1");
ll.add("2");
ll.add("5");
ListIterator li = ll.listIterator();
while (li.hasNext())
System.out.println(li.next());
public static void main(String[] args)
testList tl = new testList();
tl.test();
As we know, order is the most important feature of a List.
But this program's result is " 3 1 2 5 " which is not a sorted list!
How we understand the phrase 'order' ?
And , is there any method in Collection which can sort the elements in one collection (list or set)?
thanx a lot!

As we know, order is the most important feature of a
List. Yes, and it preserves the order you have used to put elements in the List. :)
But this program's result is " 3 1 2 5 " which is not
a sorted list!Well, what order to you actually like? "1 2 3 5"? Why not "5 3 2 1"? And for more complicated objects "natural" order may be even less obvious. And never forget that List may contain objects that belong to different classes - for example Integer, String and Date - how they are to be ordered? (Of course, such usage is not recommended).
How we understand the phrase 'order' ?
And , is there any method in Collection which can
sort the elements in one collection (list or set)?There are sort-methods in java.util.Collections class.

How to understand the logic of existing code

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