When to use byte

Is it really worth to use primitive datatypes like byte and short over int, when arithmetic is used? I've read that byte and short are converted to int prior to arithmetic and it just seems cumbersome when some of your bytes/shorts mingle with ints. When do people actually use these datatypes other than memory critical apps?
thanks

The reason I ask is because I have some values that fit within a byte and so I thought it best to use the smallest appropriate data type, but at times working with byte has proven to be a pain so I was thinking of just moving most of my bytes to ints. I was more just concerned with the impact on memory.

Similar Messages

Error when using byte array in web service model interface

Hello everybody,
I'm using a web service model in my web dynpro application. The web service requires a byte array as import parameter.
When starting the web dynpro application the following error occurs:
com.sap.tc.webdynpro.services.exceptions.WDTypeNotFoundException: type java:byte not found
at com.sap.tc.webdynpro.services.datatypes.core.DataTypeBroker.getDataType(DataTypeBroker.java:216)
I'm using byte arrays several times in my application --> no problem. So why does the error say "byte not found" when using the web service?
Thanks for your help!
regards
Christian

Hi,
maybe this is the problem. The type is byte and not binary.
But I have the same problem as mentioned in the other thread: I can't change the type.
The type in the WSDL of my web service is "base64binary". Is there maybe a possibility to import a jar-file for this type?
Christian

When to use short and byte

when do i should really use byte and short anyway?
let's say i'm writing a MIDlet and i really really want to save up some memory at run time, would it be helpful if i will use short and byte if i dont need large numbers? let's say i only need a maximum representation of 500?
i know int is commonly used, but is it worth the change?

I don't know about the Micro Editon VM, but the Java Standard Edition run-time VM has no special instructions for operating using byte primitives as opposed to, say, integer or short primitives, and byte primitives in the VM are stored as ints, I believe. So, chances are your optimizations of these primitives aren't going to save you that much in terms of speed or memory. However, again, my previous comments only apply to the Standard Edition VM [feel free to correct them if I am wrong, as I am not sure if these restrictions have changed since Java v1.3 or not].
Plus, if your value is going to be a maximum of 500, you need a short because the signed byte primitive will only be valid across the -128 to 127 range.
-Dok

When I click on a link I get sent to a bunch of other sites and the problem doesn't occur when I use windows internet browser.

When I click on a link, whether e-mail, yahoo or other search engines, E-bay, Amazon, etc. I get sent to another site. If I click back and then re-click on the original site I get sent to where I wanted to be. While I am browsing on a web page of any of the above, or other sites, I sometimes get a voice ad or possibly a video, but I can't locate it or turn it off. This does not happen when I use windows internet, or it's Google chrome internet, only with Firefox. I have used Ad aware, and Mal-bytes anti-virus but they come up blank.

Do a malware check with some malware scanning programs on the Windows computer.<br />
You need to scan with all programs because each program detects different malware.<br />
Make sure that you update each program to get the latest version of their databases before doing a scan.
*http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
*http://www.superantispyware.com/ - SuperAntispyware
*http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
*http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
*http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
You can also do a check for a rootkit infection with TDSSKiller.
*http://support.kaspersky.com/viruses/solutions?qid=208280684
See also:
*"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Why CBO don't use function-base index when I use like and bind variable

Hello
I have litle problem with function-base index and like with bind variable.
When I use like with bind variable, the CBO don't use my function-base index.
For example when I create table and index:
ALTER SESSION SET NLS_SORT='BINARY_CI';
ALTER SESSION SET NLS_COMP='LINGUISTIC';
alter session set nls_language='ENGLISH';
-- DROP TABLE TEST1;
CREATE TABLE TEST1 (K1 VARCHAR2(32));
create index test1_idx on test1(nlssort(K1,'nls_sort=BINARY_CI'));
INSERT INTO TEST1
SELECT OBJECT_NAME FROM ALL_OBJECTS;
COMMIT;
When I run:
ALTER SESSION SET NLS_SORT='BINARY_CI';
ALTER SESSION SET NLS_COMP='LINGUISTIC';
SELECT * FROM TEST1 WHERE K1 = 'abcd';
or
SELECT * FROM TEST1 WHERE K1 LIKE 'abcd%';
CBO use index.
PLAN_TABLE_OUTPUT
SQL_ID 4vrmp7cshbvqy, child number 1
SELECT * FROM TEST1 WHERE K1 LIKE 'abcd%'
Plan hash value: 1885706448
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 1 (100)| |
| 1 | TABLE ACCESS BY INDEX ROWID| TEST1 | 2 | 98 | 1 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | TEST1_IDX | 2 | | 1 (0)| 00:00:01 |
Predicate Information (identified by operation id):
2 - access("TEST1"."SYS_NC00002$">=HEXTORAW('6162636400') AND
"TEST1"."SYS_NC00002$"<HEXTORAW('6162636500') )
but when I run
SELECT * FROM TEST1 WHERE K1 LIKE :1;
CBO don't use index
PLAN_TABLE_OUTPUT
SQL_ID 9t461s1669gru, child number 0
SELECT * FROM TEST1 WHERE K1 LIKE :1
Plan hash value: 4122059633
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 89 (100)| |
|* 1 | TABLE ACCESS FULL| TEST1 | 2 | 48 | 89 (3)| 00:00:02 |
Predicate Information (identified by operation id):
1 - filter("K1" LIKE :1)
What should I change to force CBO to use index.
I don't wont use index hint in query.
My oracle version:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for 64-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

OK. But why if I create normal index (create index test1_idx on test1(K1)) and return to default nls settings this same query use index.
PLAN_TABLE_OUTPUT
SQL_ID 9t461s1669gru, child number 0
SELECT * FROM TEST1 WHERE K1 LIKE :1
Plan hash value: 598212486
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 1 (100)| |
|* 1 | INDEX RANGE SCAN| TEST1_IDX | 1 | 18 | 1 (0)| 00:00:01 |
Predicate Information (identified by operation id):
1 - access("K1" LIKE :1)
filter("K1" LIKE :1)
Note
- dynamic sampling used for this statement (level=2)
when index is function-base (create index test1_idx on test1(nlssort(K1,'nls_sort=BINARY_CI')))
PLAN_TABLE_OUTPUT
SQL_ID 9t461s1669gru, child number 1
SELECT * FROM TEST1 WHERE K1 LIKE :1
Plan hash value: 4122059633
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 89 (100)| |
|* 1 | TABLE ACCESS FULL| TEST1 | 3 | 54 | 89 (3)| 00:00:02 |
Predicate Information (identified by operation id):
1 - filter("K1" LIKE :1)
Note
- dynamic sampling used for this statement (level=2)
when I create index with upper function "index test1_idx on test1(upper(K1))" the query use index
SELECT * FROM TEST1 WHERE upper(K1) LIKE :1
Plan hash value: 1885706448
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 1 (100)| |
| 1 | TABLE ACCESS BY INDEX ROWID| TEST1 | 4481 | 157K| 1 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | TEST1_IDX | 806 | | 1 (0)| 00:00:01 |
Predicate Information (identified by operation id):
2 - access("TEST1"."SYS_NC00002$" LIKE :1)
filter("TEST1"."SYS_NC00002$" LIKE :1)
Note
- dynamic sampling used for this statement (level=2)

Should I save memory by using byte, short and float?

Our teacher tells us always to use int and double. But what if I don't need such precision or large values?
Shouldn't I use byte, short and float instead?

You don't save any memory if you use floats instead of doubles in a method. These variables only exist on the stack when the method is executing. Also remember that Java may do type conversions from float to double in expressions. This may make your code slower.
If you have a class with large quantities of doubles, for example an array of 100000 doubles, then you may consider using floats, because the memory saving is substantial. If you access the array from outside the class via double methods you can easily do this change local to the class late in the development process.
I'd say generally it's better to do as your teacher says and standardize on doubles and integers. If you write your program well you can always optimize later if you have to.

Oracle 10.2.0.4 Index on timestamp column not used when SYSTIMESTAMP Used.

Hi,
I have a table A with a column B timestamp(6). The tables contains around 300000 rows..
I have created index 'idx' on the column B.
When i compare column 'B' with systimestamp, it does not use the index, whereas if i compare 'B' with sysdate it uses the index.
Eg :
select count(*) from a where b<=sysdate;
The above used the index 'idx' and executed in 1 second
select count(*) from a where b<=systimestamp;
The above does not use the index and executed in 19 seconds.
Any Clue?
Thanks in Advance

Oracle is using Internal functions when you use SYSTIMESTAMP:
Work around will be to use TO_TIMESTAMP as shown below.. Or define a function based index..
You can check performance problem querying against a "TIMESTAMP WITH TIME ZONE" column link also
SQL> create table a(b timestamp(6));
Table created.
SQL> insert into a
2 select systimestamp+(level/24) from dual connect by level <= 30000;
30000 rows created.
SQL> commit;
Commit complete.
SQL> create index ndx on a(b);
Index created.
SQL> explain plan for
2 select count(*) from a where b <= sysdate;
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 3858831102
| Id | Operation         | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |      |     1 |    13 |     1   (0)| 00:00:01 |
|   1 | SORT AGGREGATE   |      |     1 |    13 |            |          |
|* 2 |   INDEX RANGE SCAN| NDX |     1 |    13 |     1   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("B"<=SYSDATE@!)
Note
   - dynamic sampling used for this statement
18 rows selected.
SQL> explain plan for
2 select count(*) from a where b <= systimestamp;
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 3918351354
| Id | Operation          | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |     1 |    13 |    20 (15)| 00:00:01 |
|   1 | SORT AGGREGATE    |      |     1 |    13 |            |          |
|* 2 |   TABLE ACCESS FULL| A    |     1 |    13 |    20 (15)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - filter(SYS_EXTRACT_UTC(INTERNAL_FUNCTION("B"))<=SYS_EXTRACT_UTC(S
              YSTIMESTAMP(6)))
Note
   - dynamic sampling used for this statement
19 rows selected.
--"Just tried using TO_TIMESTAMP"
SQL> explain plan for
2 select count(*) from a where b <= to_timestamp(systimestamp);
Explained.
SQL>
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 3858831102
| Id | Operation         | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |      |     1 |    13 |     2   (0)| 00:00:01 |
|   1 | SORT AGGREGATE   |      |     1 |    13 |            |          |
|* 2 |   INDEX RANGE SCAN| NDX |     4 |    52 |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("B"<=TO_TIMESTAMP(TO_CHAR(SYSTIMESTAMP(6))))
14 rows selected.Edited by: jeneesh on Oct 23, 2012 11:18 AM

Using bytes or chars for String phonetic algorithm?

Hi all. I'm working on a phonetic algorithm, much like Soundex.
Basically the program receives a String, read it either char by char or by chunks of chars, and returns its phonetic version.
The question is which method is better work on this, treating each String "letter" as a char or as a byte?
For example, let's assume one of the rules is to remove every repeated character (e.g., "jagged" becomes "jaged"). Currently this is done as follows:
public final String removeRepeated(String s){
                char[] schar=s.toCharArray();
          StringBuffer sb =new StringBuffer();
          int lastIndex=s.length()-1;
          for(int i=0;i<lastIndex;i++){
               if(schar!=schar[i+1]){
                    sb.append(schar[++i]);//due to increment it wont work for 3+ repetions e.g. jaggged -> jagged
          sb.append(schar[lastIndex]);
          return sb.toString();
Would there be any improvement in this computation:public final String removeRepeated(String s){
          byte[] sbyte=s.getBytes();
          int lastIndex=s.length()-1;
          for(int i=0;i<lastIndex;i++){
               if(sbyte[i]==sbyte[i+1]){
                    sbyte[++i]=32; //the " " String
          return new String(sbyte).replace(" ","");
Well, in case there isn't much improvement from the short(16-bit) to the byte (8-bit) computation, I would very much appreciate if anyone could explain to me how a 32-bit/64-bit processor handles such kind of data so that it makes no difference to work with either short/byte in this case.

You may already know that getBytes() converts the string to a byte array according to the system default encoding, so the result can be different depending on which platform you're running the code on. If the encoding happens to be UTF-8, a single character can be converted to a sequence of up to four bytes. You can specify a single-byte encoding like ISO-8859-1 using the getBytes(String) method, but then you're limited to using characters that can be handled by that encoding. As long as the text contains only ASCII characters you can get away with treating bytes and characters as interchangeable, but it could turn around and bite you later.
Your purpose in using bytes is to make the program more efficient, but I don't think it's worth the effort. First, you'll be constantly converting between {color:#000080}byte{color}s and {color:#000080}char{color}s, which will wipe out much of your efficiency gain. Second, when you do comparisons and arithmetic on {color:#000080}byte{color}s, they tend to get promoted to {color:#000080}int{color}s, so you'll be constantly casting them back to {color:#000080}byte{color}s, but you have to watch for values changing as the JVM tries to preserve their signs.
In short, converting the text to bytes is not going to do anywhere near enough good to justify the extra work it entails. I recommend you leave the text in the form of {color:#000080}char{color}s and concentrate on minimizing the number of passes you make over it.

Anyone some info on how and when to use SafeMapping ?

Tried: "MYCOL", "String"
and "MYCOL", "System.String"
MYCOL is a VARCHAR2
{System.InvalidCastException}
[System.InvalidCastException]: {System.InvalidCastException}
Object: {System.InvalidCastException}
_COMPlusExceptionCode: -532459699
_className: Nothing
_exceptionMethod: Nothing
_exceptionMethodString: Nothing
_message: "Specified cast is not valid."
_innerException: Nothing
_helpURL: Nothing
_stackTrace: {System.Array}
_stackTraceString: Nothing
_remoteStackTraceString: Nothing
_remoteStackIndex: 0
_HResult: -2147467262
_source: Nothing
_xptrs: 0
_xcode: -532459699
Message: "Specified cast is not valid."
InnerException: Nothing
TargetSite: {System.Reflection.RuntimeMethodInfo}
StackTrace: " at Oracle.DataAccess.Client.OracleDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords)
at Oracle.DataAccess.Client.OracleDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)
at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable)
at GetTrailBlank.GetTrailingBlank.Button1_Click(Object sender, EventArgs e) in E:\DevProjs\VSNet\GetTrailBlank\GetTrailBlank.vb:line 103"
HelpLink: ""
Source: "Oracle.DataAccess"
HResult: -2147467262

For how to use Safe Type Mapping you can refer
Safe Type Mapping Sample at
http://otn.oracle.com/sample_code/tech/windows/odpnet/content.html
When to use :
Safe Type Mapping is a feature that allows OracleDataAdapter to populate a DataSet with .NET type representations of Oracle data without any data or precision loss. ODP.NET defines corruptible types (DATE, TIMESTAMP, INTERVAL DAY TO SECOND and NUMBER types) which can potentially loose precision when converted to their corresponding .NET types during database operations. By using the Safe Type Mapping feature of ODP.NET these types can be safely retrieved as String or a byte array as against their default .NET types in the DataSet to avoid precision loss.
HTH
Jagriti

WHEN TO USE SYS_REFCURSOR AND WHEN NOT TO USE REFCURSOR

SYS_REFCURSOR is a Weakly Defined Cursor
DECLARE emp_refcur SYS_REFCURSOR;
when this is so simple
why this
DECLARE TYPE emp_cur_type IS REF CURSOR RETURN emp%ROWTYPE; my_rec emp_cur_type; ?
Can anyone explain in what situations we should prefer among these ..when both can give same result set .

> WHEN TO USE SYS_REFCURSOR AND WHEN NOT TO USE REFCURSOR
When the requirements define that one is better suited than the other.
There are no hard and fast rules about when to use a specific tool. There are however basic concepts of what the purpose of the tool is, and what typical problems the tool can address.
Ref cursors in PL/SQL.. usually not the best of ideas. Ref cursors are designed for client-server processing.
1) The client makes a request for data/information.
2) PL applies the back-end server logic and construct a SQL statement for the client.
3) PL passes the SQL to the SQL engine where it is parsed and a SQL cursor created.
4) PL passes a reference handle to SQL cursor back to the client
5) The client can now fetch the rows output from the cursor.
Advantages.
- The client does not need to know SQL, db structures, business logic, etc
- The PL code can be improved, modified, new business logic added, without even touching a single byte of client code
So what are the advantages where the "client" in the above is another PL/SQL program? None really.
A "real" client (an external one like Java, C#, Delphi, etc) can receive the ref cursor handle and dynamically at run-time determine the projection (output) of the cursor.
PL code cannot (unless using the latest 11g features). In PL code, a ref cursor is actually implemented as a DBMS_SQL cursor. A DBMS_SQL cursor is to PL code what ref cursor is to Java/C#/etc.
So whether you define a strongly typed or weakly typed ref cursor in PL/SQL code... typical response is "so what?" as ref cursors are not really intended for PL code. Not that there are exceptions - they do come in handy at times.. but as exceptions to the rule.
So my response is "so what?" - it is more important to *correctly" chose what type of client cursor data type you want to use to interact with the back-end SQL cursor. Once that decision has been made (based on technical sound logic), then one can look at (minor) issues such as weak vs. strong ref cursors.

Using byte or char array?

I am trying to use byte[] or char[] to read from a socket. I used byte[] and char[], both works fine. However, I know byte is 8 bits and char is 16 bits. Does it matter which one I used?
Thanks.

When you deal with streams of plain bytes you should use input/outputstreams, not readers or writers that are meant for character streams. The inputstream equivalent to BufferedReader is BufferedInputStream and there is a method for reading a full byte[] there...
But using a "bigger" data type than you need will not cause you big problems.

How to write newline character to file using bytes along with content

Hi All,
I need to write headers into the file using byte[]. I am creating the strings of header which will form the different rows in the file. I am new to java and would like to know how to embed new line character so that when the byte[] is written to file headers come in different rows.
like
hrd1:abcd
hdr2:1234
when i embed \n and \r in string and do getBytes() and write it to file, some boxes are written in the file and everything comes into single line.
Please advice me the correct way .
Thanks in advance.
Cheers!!
Puneet

not sure about it, but i was always told that "\r\n" meant "new line" on "lots of documents" whereas "\n" only or "\r" only were meaningless on some type of documents

Case Structure using Byte Array

I have an array that has 9 bytes. I need to determine method for selecting a case in case structure when a bit is high.
I know how to do it when it is 1 byte but I am not sure the best method to use when its nine byte array.
Can someone provide me suggestions? Or example code?
Thanks.....

altenbach wrote:
Assuming you have a Boolean array with 9 elements, use "boolean array to number" and wire to the selector terminal. Create cases for all relevant patterns and leave the default case empty.
If only one element can be true at any given time, use search array and search for TRUE. Wire the output to the selector. Leave the "-1" case empty.
I think the poster has an array of nine bytes, each with the appropriate booleans. Therefore, I like jcarmody's suggestion that he index the array and performs the operations that the poster is already familiar with.
Assuming an array of booleans, the first method you described is okay if there is a specific action for each pattern. In most of the scenarios I've worked with, each bit represented a specific test, for instance, and there would be a lot of duplicate code if I used that method. (For instance, binary cases 10 and 11 would both have test subVIs for test 2.) For something like that, I would all my tests in sequence (using error in/out for dataflow, of course) and have T/F cases around each one with the indexed boolean array controlling which tests would be run. Of course I tend to see things in a literal way, so if the requirements say "do the selected tests in this order", that's how I would develop it. Maybe there's a better way programmatically?
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

When to use BufferedInputStream/OutputStream/Reader/Writer

I'd be very grateful if someone could explain when to use BufferedInputStream, etc., and what the dis/advantages are.
TIA
Shaun

data channels such as files sockets, etc, tend to be
a) slow
b) block oriented
BufferedOutputStream attempts to mitigate this by presenting data in block format. Rather than a bunch of little segments of bytes.

AVG Secure Search appears when I use Google Search from my Home page only.

My home page is the Firefox default page with the Google searchbar. I like getting occasional messages from Firefox when I log in so I don't want to change my homepage. However, when I use the searchbar ''on my homepage only'', I get the unsatisfactory AVG Secure Search results.
UPDATE: I now realize all the troubleshooting information I included in my original question appears under the "More System Details" link next to the question, not in the body of the question. I have copied it here to make it easier to see what I have already done to try to solve the problem, as well as describe the one clue I have that may be relevant:
I have tried all the fixes on various threads, but my about:config is now pristine (no avg or isearch mentions; keyword.url is default). Closest solution is that at https://support.mozilla.org/en-US/questions/866327 , which requires changing my home page.
Oddly, AVG Secure Search is ''not'' a problem when I use the Google toolbar or search from the Google website, only when I use the search bar that appears on my home (start) page. This is true even when I return to my home page--if I search from the Google search bar in the middle of the page, I get sent to AVG Safe Search. (isearch.avg.com).
I read in one thread a suggestion to delete my chromeappsstore.sqlite file in my Profile folder. As promised, Firefox created a new one when I restarted it; however, the search bar in the middle of my home home page did not work at all. Tried this three times before restoring my original.
I do not have an application that will open a sqlite file, but I tried doing so in Excel and found a cell containing the following:
emoh.:moz-safe-aboutsearch-engine{"name":"AVG Secure Search","searchUrl":"http://isearch.avg.com/search?cid={7A3C25A0-E345-4507-AA31-D98F596A81A9}&mid=c48135235ba247d18ac1d14b344db451-addd29eab2809954d5abdf0b991a5b911a297819&ds=is015&lang=en&v=10.0.0.7&pr=sa&d=&sap=dsp&q=_searchTerms_"}
I have no clue what that means, but it is the only thing I can find related to Firefox that still mentions AVG and isearch.avg.com.
At this point my best guess (but it is a guess) is that the chromeappsstore.sqlite file is a key to the complete solution, but I do not have enough knowledge to go beyond and address it. I appreciate any help you anyone can offer.

Here is the way to get rid of the problem once and for all:
http://forums.avg.com/ww-en/avg-forums?sec=thread&act=show&id=196402#post_196402

When to use byte

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