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.

Similar Messages

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.

Oracle Best practices for changing Byte to Char on Varchar2 columns

Dear Team,
Application Team wanted to change Byte to Char on Varchar2 columns to accommodate Multi byte character on couple of production tables.
Wanted to know is it safe to have mixture of BYTE and CHAR semantics in the same table i have read on the couple of documents that It's good practice to avoid using a mixture of BYTE and CHAR semantics columns in the same table.
What happens if we have mixture of BYTE and CHAR semantics columns in the same table?
Do we need to gather stats & rebuild indexes on the table after these column changes .
Thanks in Advance !!!
SK

Application Team wanted to change Byte to Char on Varchar2 columns to accommodate Multi byte character on couple of production tables.
Wanted to know is it safe to have mixture of BYTE and CHAR semantics in the same table i have read on the couple of documents that It's good practice to avoid using a mixture of BYTE and CHAR semantics columns in the same table.
No change is needed to 'accommodate Multibyte characters'. That support has NOTHING to do with whether a column is specified using BYTE or CHAR.
In 11g the limit for a VARCHAR2 column is 4000 bytes, period. If you specify CHAR and try to insert 1001 characters that each take 4 bytes you will get an exception since that would require 4004 bytes and the limit is 4000 bytes.
In practice the use of CHAR is mostly a convenience to the developer when defining columns for multibyte characters. For example for a NAME column you might want to make sure Oracle will allocate room for 50 characters REGARDLESS of the actual length in bytes.
If you provide a name of 50 one byte characters then only 50 bytes will be used. Provide a name of 50 four byte characters and 200 bytes will be used.
So if that NAME column was defined using BYTE how would you know what length to use for the column? Fifty BYTES will seldom be long enough and 200 bytes SEEMS large since the business user wants a limit of FIFTY characters.
That is why such columns would typically use CHAR; so that the length (fifty) defined for the column matches the logical length of the number of characters.
What happens if we have mixture of BYTE and CHAR semantics columns in the same table?
Nothing happens - Oracle could care less.
Do we need to gather stats & rebuild indexes on the table after these column changes .
No - not if you by 'need' you mean simply because you made ONLY that change.
But that begs the question: if the table already exists, has data and has been in use without their being any problems then why bother changing things now?
In other words: if it ain't broke why try to fix it?
So back to your question of 'best practices'
Best practices is to set the length semantics at the database level when the database is first created and to then use that same setting (BYTE or CHAR) when you create new objects or make DDL changes.
Best practices is also to not fix things that aren't broken.
See the 'Length Semantics' section of the globalization support guide for more best practices
http://docs.oracle.com/cd/E11882_01/server.112/e10729/ch2charset.htm#i1006683

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

Use byte array of PDF to display PDF in IE browser

I get byte array of PDF as input argument. I need to use byte array to display PDF in IE browser. I am writing code in doGet method of Servlet to accomplish this. However, PDF never gets displayed. I see Acrobat starting, but original PDF never gets displayed in browser.
I am using code below in doGet of Servlet:
resp.setContentType("application/pdf");
resp.setHeader("Expires", "0");
resp.setHeader("Cache-Control","must-revalidate, post-check=0,
pre-check=0");
resp.setHeader("Pragma", "public");
resp.setHeader("Pragma", "no-cache"); //HTTP 1.0
resp.setDateHeader("Expires", 0); //prevents caching at the proxy
server
resp.setHeader("Cache-Control", "no-cache"); //HTTP 1.1
resp.setHeader("Cache-Control", "max-age=0");
resp.setHeader("Content-disposition", "inline; filename=stuff.pdf");
byte[] inBytes = getBytesOfPDF(...);
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
if(inBytes !=null){
outStream.write(inBytes);
outStream.flush();
I added dummy name of PDF (stuff.pdf) for display, as I heard IE requires a file name with .pdf extension for display.
But I had no luck with the code above.
Any help with code will be appreciated.
[email protected]

Hi
Am using the same code and i am able to get the PDF out.
          /* Finally writing it into a PDF */
               response.setContentType("application/pdf");
               /* filename could be any thing */
               response.setHeader("Content-Disposition",
                         "attachment; filename=Report.pdf");
               response.setContentLength(content.length);
               response.getOutputStream().write(content);
               response.getOutputStream().flush();
But this also throws a error in the server :
java.lang.IllegalStateException: getOutputStream() has already been called for this response
     at org.apache.catalina.connector.Response.getWriter(Response.java:606)
     at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:195)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:344)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:280)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:225)
     at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:174)
     at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:239)
     at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1142)
     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:879)
     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:792)
     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476)
     at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:441)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
     at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
     at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
     at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
     at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
     at org.ca.ielts.presentationtier.servlet.AuthorisationAuthenticationFilter.doFilter(Unknown Source)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:868)
     at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:663)
     at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
     at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
     at java.lang.Thread.run(Thread.java:595)
Any Clues how this has to be fixed.????

Getting int values from a char array

Hi,
I need to make a fast program which reads lots of data from files and process them. I need to interpret these data as int's. To be more efficient and avoid to make a lot of disk access, I allocate in memory buffers part of the data, then process it and then allocate new data. The problem is that if I want to allocate data in memory buffers, all the methods that enables me to do that receceive as a parameter only a an array of chars, and as I have mentioned I need to interpret the data as a 4 bytes int. The static methods of Array to get the int value from a position ar not useful because the onlye get the int value of the indexed byte (or char); this method doesn't take 4 bytes from the index to build an int.
My question is: is there any way to build an int from 4 bytes? or can I get the int's in this way directly from the buffer?
Thank you,

Isn't this one of the prime examples of using java.io.DataOutputStream and java.io.DataInputStream?

Reading .txt file into char array, file not found error. (Basic IO)

Iv been having some trouble with reading characters from a text file into a char array. I havnt been learning io for very long but i think im getting the hang of it. Reading and writing raw bytes
and things like that. But i wanted to try using java.io.FileReader to read characters for a change and im having problems with file not found errors. here is the code.
try
File theFile = new File("Mr.DocumentReadMe.txt");
String path = theFile.getCanonicalPath();
FileReader readMe = new FileReader(path);
char buffer[] = new char[(int)theFile.length()];
int readData = 0;
while(readData != -1)
readData = readMe.read(buffer);
jEditorPane1.setText(String.valueOf(buffer));
catch(Exception e)
JOptionPane.showMessageDialog(null, e,
"Error!", JOptionPane.ERROR_MESSAGE);
The error is: java.io.FileNotFoundException: C:\Users\Kaylan\Documents\NetBeansProjects\Mr.Document\dist\Mr.DocumentReadMe.txt (The system cannot find the file specified)
The text file is saved in the projects dist folder. I have tried saving it elsewhere and get the same error with a different pathname.
I can use JFileChooser to get a file and read it into a char array with no problem, why doesnt it work when i specify the path manually in the code?

Well the file clearly isn't there. Maybe it has a .txt.txt extensionthat Windows is kindly hiding from you - check its Properties.
But:
String path = theFile.getCanonicalPath();
FileReader readMe = new FileReader(path);You don't need all that. Just:
FileReader readMe = new FileReader(theFile);And:
char buffer[] = new char[(int)theFile.length()];You don't need a buffer the size of the file, this is bad practice. Use 8192 or whatever.
while(readData != -1)
readData = readMe.read(buffer);
}That doesn't make sense. Read the data into the buffer and repeat until you get EOF? and do nothing with the contents of the buffer? The canonical read loop in Java goes like this:
while ((count = in.read(buffer)) > 0)
out.write(buffer, 0, count); // or do something else with buffer[0..count-1].
jEditorPane1.setText(String.valueOf(buffer));Bzzt. That won't give you the content of 'buffer'. Use new String(buffer, 0, count) at least.

Importing text file into 2D char array

Hey folks. I've aged a few years trying to figure this project out. Im trying to make a crossword puzzle and am having problems importing the answer letters into a 2D array of 15*15. The text file would look something like this:
LAPSE TAP RAH
AVAIL OLE ODE
BARGE PARADOX
etc
I have JTextFields that the user will answer and a button the user can press to see if the answers are right by comparing the 2D array answer with what the user inputted.-the user input would be scanned and put into a 2D array also.
How should i go about inserting each letter into an array? The spaces i would later need to make code to grey out the text field. This is what i have so far. Forgive me if its sloppy.
     class gridPanel extends JPanel
          //----Setting Grid variables
          private static final int ROWS = 15;
          private static final int COLS = 15;
          String[] letters = { "A", "B", "C", "D", "E" };// To test entering strings into array
           gridPanel()
             this.setBackground(Color.BLUE);
             //.......Making my JTextField grid for user input
             JTextField[][] grid = new JTextField[ROWS][COLS];
             for(int ROWS = 0; ROWS<grid.length; ROWS++)
                 for(int COLS = 0; COLS<grid.length; COLS++)
                     grid[ROWS][COLS] = new JTextField(1);
                     add(grid[ROWS][COLS]);
                 //grid[ROWS][COLS].setText("" + letters[0]);
             String an = null;
             StringTokenizer tokenizer = null;
             Character[][] answer = new Character[ROWS][COLS];
          try{
             BufferedReader bufAns = new BufferedReader( new FileReader("C:\\xwordanswers.txt"));
             for (int rowCurrent = 0; rowCurrent < ROWS; rowCurrent++)
          an = bufAns.readLine();
          tokenizer = new StringTokenizer(an);
          for (int colCurrent = 0; colCurrent < COLS; colCurrent++) {
          char currentValue = tokenizer.nextToken().charAt(0);//Needs to be changed to reflect each letter
                    answer[rowCurrent][colCurrent] = currentValue;
                System.out.println(currentValue);
          }catch (IOException ioex)
                    System.err.println(ioex);
                    System.exit(1);
        }//xword graphics end
      This obviously prints the first char of each word, it also gives me an "Exception in thread "main" java.util.NoSuchElementException" error for some reason.
Any help is greatly appreciated.
John

If the file format is stored as follows:
APPLE
L A
PARSE
N E
PEAR then we can parse this into a 2D char array:
char[][] readMap(String fileName) {
    char[][] ret = new char[ROWS][COLS];
    FileInputStream FIS = new FIleInputStream(fileName);
    int i, j;
    for(i = 0; i < ROWS; i++)
        for(j = 0; j < COLS; j++)
            ret[i][j] = FIS.read();
    FIS.close();
    return ret;
}Then you can use the resulting 2D char array in your answer checking mechanism.
Hope this helps~
Alex Lam S.L.

Converting bytes to character array problem

I am trying to convert a byte array into a character array, however no matter which Character Set i choose i am always getting the '?' character for some of the bytes which means that it was unable to convert the byte to a character.
What i want is very simple. i.e. map the byte array to its Extended ASCII format which actually is no change in the bit represtation of the actual byte. But i cannot seem to do this in java.
Does anyone have any idea how to get around this problem?

Thanks for responding.
I have however arrived at a solution. A little un-elegant but it seems to do the job.
I am converting each byte into char manually by this algorithm:
          for (int i=0;i<compressedDataLength;i++)
               if (((int) output)<0)
                    k=(127-((int) output[i]));
                    outputChr[i]=((char) k);
               else
                    k=((int) output[i]);
                    outputChr[i]=((char) k);
               System.out.println(k);
where output is the byte array and outputChr is the character array

Problem with getting bulk output in 2D char array in precompiler program

In a ANSI dynamic SQL precompiler (Pro*C) program how do I obtain the bulk output of a column of string type (varchar or char) in a host variable array.
I do not want to use reference semantics, instead want to use get descriptor directive. Is it possible to use 2 dimensional character array for getting the output?
I am dynamically allocating memory for the host arrays.

Consider asking this in the forum for C and C++ (OCI and OCCI).

Form English Char ( Single Byte ) TO Double Byte ( Japanese Char )

Hello EveryOne !!!!
I need Help !!
I am new to Java ,.... I got assignment where i need to Check the String , if that string Contains Any Non Japanse Character ( a~z , A~Z , 0 -9 ) then this should be replaced with Double Byte ( Japanese Char )...
I am using Java 1.2 ..
Please guide me ...
thanks and regards
Maruti Chavan

hello ..
as you all asked Detail requirement here i an pasting C code where 'a' is passed as input character ..after process it is giving me Double Byte Japanese "A" .. i want this to be Done ..using this i am able to Convert APLHA-Numeric from singale byte to Doubel Byte ( Japanse ) ...
Same program i want to Java ... so pleas guide me ..
#include <stdio.h>
int main( int argc, char *argv[] )
char c[2];
char d[3];
strcpy( c, "a" ); // a is input char
d[0] = 0xa3;
d[1] = c[0] + 0x80;
printf( ":%s:\n", c ); // Orginal Single byte char
printf( ":%s:\n", d ); // Converted Double Byte ..
please ..
thax and regards
Maruti Chavan

Using byte[] as a key in a concurrent dictionary.

Hi All,
I have created a Concurrent Dictionary with key as a object containing byte array using IEqualityComparer. I was wondering how do I create a hash code for each such object when adding to my dictionay. I tried below creating hash code using sum of all
the bytes present in the byte array of the object, but the performance is worst when we try to compare with normal dictionary with some existing data type as a key. Please suggest how do I improve performance of my dictionary with custom key(object with byte
array).
Thanks and Regards,
Lucas

Calculating the hash of a large byte array can be more expensive than handling hash collisions. So perhaps use your special knowledge about the data to extract a few bytes from the array to use in the hash.
eg
public int GetHashCode(byte[] obj)
if (obj == null)
return -1;
if (obj.Length == 0)
return 0;
if (obj.Length < 64)
return obj.Length * obj[1];
var fp = new byte[4];
fp[0] = obj[0];
fp[1] = obj[16];
fp[2] = obj[27];
fp[3] = obj[55];
return obj.Length ^ BitConverter.ToInt32(fp, 0);
David
David http://blogs.msdn.com/b/dbrowne/

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.

Byte or CHAR? - as Unit

Hi all,
DB - 9.2
Which is the better option to keep unit as Byte or CHAR while using the VARCHAR2 datatype?
Suppose unit is selected as Byte then is it not cumbersome to calculate the max. no. of characters could be stored in the field?

Hi!
I'd propose CHAR, because with BYTE it is dependent of the character set how many characters you can store in your field. This means -> calculate :)
Best regards,
Daniel

Help:How to get a java String value from a C char array?

Hi,everyone,could you help me?
the following is a C struct that i want to recieve a short message:
struct MO_msg{
unsigned long long msgID;          //Message ID
char      dest_id[21]; //Destination Mobile Phone Number
char      service_id[10];     //
Now I want to put the "dest_id " value of this struct into a Java String variable.But I dont know how to implement it!
The following is a block of source code that i implement this functions.But it cant get a String value ,and throw out a Exception:
java.lang.NullPointerException
at java.lang.StringBuffer.append(StringBuffer.java:389)
JNIEXPORT jint JNICALL Java_md_EMAP_thread_RubeMOTSSX_getMO
(JNIEnv * env, jobject obj, jint connId, jobject mo){
     struct MO_msg MO;
     tssx_cmpp_api_debug_flag = 1;
     int result = CMPP_Get_MO((int)connId,&MO);
     if (result == 0){
          jclass cls = (*env)->GetObjectClass(env,mo);
          jfieldID msgId = (*env)->GetFieldID(env,cls,"msgId","J");
          jfieldID dest_Id = (*env)->GetFieldID(env,cls,"dest_Id","Ljava/lang/String;");
          jfieldID serviceId = (*env)->GetFieldID(env,cls,"serviceId","Ljava/lang/String;");
          (*env)->SetLongField(env,mo,msgId,MO.msgID);
          (*env)->SetCharField(env,mo,dest_Id,*destId);
          (*env)->SetCharField(env,mo,serviceId,MO.service_id);
     return result;
Please help me!Thanks!

bschauwe:Thank you for your help!
Yes,just as you say,using NewString Or NewStringUTF can import a C char array into a Java String variable! But now I have another question,when i use these two functions ,i found that it cant deal with Chinese character!
do you have such experiences to deal with another language charset?if you have ,can you tell me how to deal with it.

Using byte or char array?

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