Ranchers,Clarification on UTF-8 in Java

[Deepak Lal]

Hi Ranchers,
I'm reading a file(C:/Documents and Settings/Administrator/Desktop/myFiles/Example.txt) which is saved as UTF-8 encoding.(attached in this post).

/*
* C:/Documents and Settings/Administrator/Desktop/myFiles/Example.txt is the file which is of encoding Type UTF-8(when opened in ultra edit shows 3 junk characters(in hex mode)(prefixed to (1001528770) in
* beginning of file)
* and when passed as shown below,we see that it is replaced by ?,The buffered reader object has a ? prefixed to it.(see displayed output)
* can you help me on this.I need the question mark(?) to be disappeared in bufferedReader Object.
* please please calling all experts in Java to help me.
*/

see below example program executed on JDK 1.6 under eclipse.and output also displayed as shown below.

Requirement: i want to remove the ? prefixed to the line(Line Read is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07)
How do we accomplish this ??? please need inputs ??

File contents are below which should be saved as UTF-8 and then passed as an argument to below program
-----------------------------------------------------------------------------------------------------------------------------
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
------------------------------------------------------------------------------------------------------------------------------

Sample Program see below.(Attached File is Example.txt which is used for parsing)

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;

/**
 * @author Deepak  AL
 * @Date 06 June 2009
 * @Test Program written at Home.
 */
public class TestUTF{
	
	public BufferedReader check(){
	
		BufferedReader bufferedReader = null;               
        try
        {            
                bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("C:/Documents and Settings/Administrator/Desktop/myFiles/Example.txt"),"UTF-8"));                
                String  line = bufferedReader.readLine();
                System.out.println("Line Read is "+line);
                // buffered reader has a ? special character  now ( can i modify bufferedReader object now)
                // ? ( Question mark) in bufferedReader object has to be removed ,could you advice on how to proceed
                // further i want to return a bufferedReader Object only after removing the question mark (?)
        }catch(Exception e){
                 System.out.println("Exception raised ::"+e.getMessage());
        }

        return bufferedReader;   // only need to return bufferedReader object.
	
	}	
	
	public static void main(String args[]){
		 TestUTF tuf = new TestUTF();
		 BufferedReader buf = tuf.check();
		 System.out.println("Buffered Reader -->"+buf);
	}	
}



Output generated is below
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Line Read is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
Buffered Reader -->java.io.BufferedReader@3e25a5
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Please Help................. :argh: :argh: :argh: :argh: :argh: :banghead: :banghead: :banghead: :banghead:


I will be highly obliged if you can help me.

Deepak A L

(Please Note :: unable to attach screenshots---Moderators..please look into this )

[Deepak Lal]

Please help me on this.
Inputs/Suggestions plzzzz



Deepak

[K. Tsang]

once the data is read into a byte array, try using new String (byte[], "UTF-8"). I don't know if this will work or not. You may want to look through the Java Internationalization tutorial here.

[Deepak Lal]

TSang wrote:
once the data is read into a byte array, try using new String (byte[], "UTF-8").

My Comments : i want the ?(question mark) to be removed in the bufferedReader object and again i need to return the bufferedReader object ONLY. I have googled enough and did not find any help..

return type should be bufferedReader object without the ?(question mark)

Please suggest on how to proceed....

[Henry Wong]

Please suggest on how to proceed....

Good, bad, or indifferent, you kinda decided on how to proceed...

i want the ?(question mark) to be removed in the bufferedReader object and again i need to return the bufferedReder object. I have googled enough and did not find any help..

return type should be bufferedReader object and without the ?

Extend the BufferedReader class, and override the readXXX() methods to remove any questions marks. Then instantiate it, and return it. An instance of your new class IS-A BufferReader instance, and it will remove the question marks.

Do I think that this is a good idea? Not really. But this is what you want -- and isn't hard to implement.

Henry

[Deepak Lal]

Henry ,
could you please send me the sample code...this is really difficult for me...
Please help me for this...i have been struggling to get this thing ......

Please henry sample code needed.

Please again requesting you for sample code...




Deepak

[Deepak Lal]

Henry ,
could you please send me the sample code...this is really difficult for me...
Please help me for this...i have been struggling to get this thing ......

Please henry sample code needed.

Please again requesting you for sample code...




Deepak

[Henry Wong]

Sorry, but the JavaRanch is not a code mill...

http://faq.javaranch.com/java/NotACodeMill

I described it enough for you to do it -- or at the least, get started. I would recommend that you attempt it. You can always ask for more clarification once you run into an issue.

Henry

[Deepak Lal]

Ok henry, i will try and will get back to you in the same thread,please reply back in case i have any clarifications.

[Narendira Sarma]

Deepak,

No one is going to be so urgent to answer your question in the same way you are. Because its your problem.

Removing a "?" is very simple with using String.replace() function. But that is not going to help you, as more and more question marks can appear anywhere in the lines you read from the file.

Try to analyze your file. If Java (or IDE) is displaying a ? then it clearly suggests that the character is not supported on the used encoding. Try to print "byte by byte" and see if the byte relating to "?" is out of range off the printable characters.

Check if your IDE (if you are using some IDE) is capable of showing those characters.

I am just giving you suggestions from what you have presented.

These might help you.

[Deepak Lal]

Thanks for information.let me try at my end again.

[Deepak Lal]

Hi Sarma and Henry,
I have tried the below,could you help me further please.....

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;

/**
 * @author Deepak  AL
 * @Date 06 June 2009
 * @Test Program written at Home.
 */
public class TestUTF{
	
	public static String byteToHex(byte data) {

        StringBuffer buf = new StringBuffer();
        buf.append(toHexChar((data >>> 4) & 0x0F));
        buf.append(toHexChar(data & 0x0F));

        return buf.toString();
    }
	
	public static char toHexChar(int i) {
        if ((0 <= i) && (i <= 9)) {
            return (char) ('0' + i);
        } else {
            return (char) ('a' + (i - 10));
        }
    }
	
	public BufferedReader check(){
	
		BufferedReader bufferedReader = null;               
        try
        {       //boolean UTF8_WITH_BOM = false;     
                bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("C:/Documents and Settings/Administrator/Desktop/UTF8RDFiles/Example.txt"),"UTF-8"));                
                String  line = bufferedReader.readLine();
                byte[] fileArray = line.getBytes("UTF-8");
                
                System.out.println("Byte fileArray Length is "+fileArray.length);
                for (int i =0;i<fileArray.length ;i++){
                	                  	  
                	  System.out.println(
                              "fileArray[" + i + "] = " +
                              ((int)fileArray[i] < 9  ? "  " : "") +
                              ( ((int)fileArray[i] > 9 && (int)fileArray[i] <= 99) ? " " : "") +
                              fileArray[i] + " : " +
                              " HEX=(0x" + byteToHex(fileArray[i]) + ") : " +
                              " charValue=(" + (char)fileArray[i] + ")");                	                  	                   	   	            	                	        
                }
             // how to proceed further  there are 3 question mark available...please advice ranchers.
               
        }catch(Exception e){
                 System.out.println("Exception raised ::"+e.getMessage());
        }

        return bufferedReader;   // only need to return bufferedReader object.
	
	}	
	
	public static void main(String args[]){
		 TestUTF tuf = new TestUTF();
		 BufferedReader buf = tuf.check();
		 System.out.println("Buffered Reader -->"+buf);
	}	
}

output
---------------
Byte fileArray Length is 68
fileArray[0] =   -17 :  HEX=(0xef) :  charValue=(?)
fileArray[1] =   -69 :  HEX=(0xbb) :  charValue=(?)
fileArray[2] =   -65 :  HEX=(0xbf) :  charValue=(?)
fileArray[3] =  49 :  HEX=(0x31) :  charValue=(1)
fileArray[4] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[5] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[6] =  49 :  HEX=(0x31) :  charValue=(1)
fileArray[7] =  53 :  HEX=(0x35) :  charValue=(5)
fileArray[8] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[9] =  56 :  HEX=(0x38) :  charValue=(8)
fileArray[10] =  55 :  HEX=(0x37) :  charValue=(7)
fileArray[11] =  55 :  HEX=(0x37) :  charValue=(7)
fileArray[12] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[13] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[14] =  80 :  HEX=(0x50) :  charValue=(P)
fileArray[15] =  72 :  HEX=(0x48) :  charValue=(H)
fileArray[16] =  80 :  HEX=(0x50) :  charValue=(P)
fileArray[17] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[18] =  65 :  HEX=(0x41) :  charValue=(A)
fileArray[19] =  66 :  HEX=(0x42) :  charValue=(B)
fileArray[20] =  81 :  HEX=(0x51) :  charValue=(Q)
fileArray[21] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[22] =  80 :  HEX=(0x50) :  charValue=(P)
fileArray[23] =  72 :  HEX=(0x48) :  charValue=(H)
fileArray[24] =  80 :  HEX=(0x50) :  charValue=(P)
fileArray[25] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[26] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[27] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[28] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[29] =  83 :  HEX=(0x53) :  charValue=(S)
fileArray[30] =  72 :  HEX=(0x48) :  charValue=(H)
fileArray[31] =  65 :  HEX=(0x41) :  charValue=(A)
fileArray[32] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[33] =  49 :  HEX=(0x31) :  charValue=(1)
fileArray[34] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[35] =  51 :  HEX=(0x33) :  charValue=(3)
fileArray[36] =  52 :  HEX=(0x34) :  charValue=(4)
fileArray[37] =  53 :  HEX=(0x35) :  charValue=(5)
fileArray[38] =  54 :  HEX=(0x36) :  charValue=(6)
fileArray[39] =  55 :  HEX=(0x37) :  charValue=(7)
fileArray[40] =  56 :  HEX=(0x38) :  charValue=(8)
fileArray[41] =  57 :  HEX=(0x39) :  charValue=(9)
fileArray[42] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[43] =  84 :  HEX=(0x54) :  charValue=(T)
fileArray[44] =  97 :  HEX=(0x61) :  charValue=(a)
fileArray[45] = 110 :  HEX=(0x6e) :  charValue=(n)
fileArray[46] =  32 :  HEX=(0x20) :  charValue=( )
fileArray[47] =  89 :  HEX=(0x59) :  charValue=(Y)
fileArray[48] =  97 :  HEX=(0x61) :  charValue=(a)
fileArray[49] =  32 :  HEX=(0x20) :  charValue=( )
fileArray[50] =  76 :  HEX=(0x4c) :  charValue=(L)
fileArray[51] = 105 :  HEX=(0x69) :  charValue=(i)
fileArray[52] = 110 :  HEX=(0x6e) :  charValue=(n)
fileArray[53] = 103 :  HEX=(0x67) :  charValue=(g)
fileArray[54] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[55] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[56] =  54 :  HEX=(0x36) :  charValue=(6)
fileArray[57] =  58 :  HEX=(0x3a) :  charValue=(:)
fileArray[58] =  49 :  HEX=(0x31) :  charValue=(1)
fileArray[59] =  49 :  HEX=(0x31) :  charValue=(1)
fileArray[60] =  58 :  HEX=(0x3a) :  charValue=(:)
fileArray[61] =  50 :  HEX=(0x32) :  charValue=(2)
fileArray[62] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[63] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[64] =  56 :  HEX=(0x38) :  charValue=(8)
fileArray[65] =  59 :  HEX=(0x3b) :  charValue=(;)
fileArray[66] =  48 :  HEX=(0x30) :  charValue=(0)
fileArray[67] =  55 :  HEX=(0x37) :  charValue=(7)
Buffered Reader -->java.io.BufferedReader@3e25a5

The first 3 are illegal i need to remove them and assign it back to bufferedReader object ... please advice....

[Henry Wong]

The first 3 are illegal i need to remove them and assign it back to bufferedReader object ... please advice....

I don't know what more to tell you... You have demostrated that there are illegal characters in the stream (twice) and the correct answer here is to remove it from the string.... But you don't want that -- you want the BufferedReader to not return it.

This means you have two choices...

1. Do the suggestion that I mentioned before (see previous post).

2. Or read it all in -- to a char array. Get rid of the illegal chars. And then used the BufferedReader on a CharArrayReader.

Either will work.... You just have to do it. And we can't give you any hints in the right direction, if you don't actually start.

I have tried the below,could you help me further please.....

It is nice that you tried something, but it would have been better if you tried what was mentioned. So, I guess, my recommendation would be... to reread the previous posts, as you haven't use that help yet.

Henry

[Paul Clapham]

You probably just have a byte-order mark (BOM) at the beginning of your file. Some Microsoft programs put that there even though it isn't required or even necessary for documents formatted in UTF-8. So why not just skip it?

[Henry Wong]

Just thought of something -- if the illegal characters are always in the beginning, then one other option would be to read off the characters before returning the BufferedReader...

Henry

[Paul Clapham]

Henry Wong wrote:
Just thought of something -- if the illegal characters are always in the beginning, then one other option would be to read off the characters before returning the BufferedReader...

Henry

Which they are, according to the very detailed post. Which also shows that they are indeed a UTF-8 byte order mark; see the Wikipedia article http://en.wikipedia.org/wiki/Byte_order_mark to confirm that.

[Deepak Lal]

Yes you all are absolutely correct it is a UTF 8 file wityh BOM,we need to parse it and if there are any illegal characters in the beginning of the file,Then skip it,how can i accomplish it...Please help me

henry wrote:
Just thought of something -- if the illegal characters are always in the beginning, then one other option would be to read off the characters before returning the BufferedReader...

but do i accomplish it....please need help on this henry.... you are saying read off the characters but i dont know how to accomplish it....can you tell me which api supports reading off the first 3 bytes and then return it back to bufferedReader....



Regards
Deepak

[Henry Wong]

Deepak Lal wrote:
but do i accomplish it....please need help on this henry.... you are saying read off the characters but i dont know how to accomplish it....can you tell me which api supports reading off the first 3 bytes and then return it back to bufferedReader....

Take a look at the BufferedReader methods -- particularly the read(), mark(), and reset() methods.

Basically, mark() the beginning of the file, then read() the first three characters (not a line, just the first three characters). If the first three characters are junk characters, then you are done. Simply return the BufferedReader back from the method. If the first three characters are not junk characters, then reset() the buffered reader, and then return it back from the method.

Anyone who uses the returned BufferedReader will not get the junk characters, when they try to read from it (as you already taken it off from the stream).


And again, this only works if the junk characters are at the beginning. For anything else, you have to use either of the other two suggestions already mentioned.

Henry

[Deepak Lal]

Hi Henry
Tried ,but its not working

see below:

                
                bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("C:/Documents and Settings/Administrator/Desktop/UTF8RDFiles/Example.txt"),"UTF-8"));                
                String  line = bufferedReader.readLine();
                System.out.println("previous line is "+line); //shows only 1 junk character. ? (@ the beginning of the file see below output clearly for details.)
                //previous line is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
                
                bufferedReader.mark(0);                                      // marks the beginning of the line
                for(int j=0;j<1;j++){                                           // j<1 since we have only one junk character.
                  int k = bufferedReader.read();                            //read the first character.
                  System.out.println("k is "+k);                            // k is coming as 49(integer value) for charValue(1) which is not a junk character but as we see line is having junk character. ? 
                }                                                                       // k is not displaying -17(integer value) for charValue(?)


Please advice on this now. I did as u suggested...what is wrong now....  

 
output is
-----------------------------------------------------------------------------

previous line is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
k is 49                // which is not a junk character as see below.
Byte fileArray Length is 68
fileArray[0] =   -17 :  HEX=(0xef) :  charValue=(?)
fileArray[1] =   -69 :  HEX=(0xbb) :  charValue=(?)
fileArray[2] =   -65 :  HEX=(0xbf) :  charValue=(?)
fileArray[3] =  49 :  HEX=(0x31) :  charValue=(1)

-----------------------------------------------------------------------------

Please suggest.




Deepak

[Henry Wong]

Please advice on this now. I did as [you] suggested...what is wrong now....

Please read my post again. You are not doing anything close to what I suggested.

Henry

[Deepak Lal]

Henry Wrote :
Take a look at the BufferedReader methods -- particularly the read(), mark(), and reset() methods.

Basically, mark() the beginning of the file, then read() the first three characters (not a line, just the first three characters). If the first three characters are junk characters, then you are done. Simply return the BufferedReader back from the method. If the first three characters are not junk characters, then reset() the buffered reader, and then return it back from the method.

Anyone who uses the returned BufferedReader will not get the junk characters, when they try to read from it (as you already taken it off from the stream).

Even the code in my previous post is doing the same steps.( as you have suggested)(junk character is @ beginning of file)

            bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("C:/Documents and Settings/Administrator/Desktop/UTF8RDFiles/Example.txt"),"UTF-8"));                   
                String  line = bufferedReader.readLine();   
                System.out.println("previous line is "+line); //shows only 1 junk character. ? (@ the beginning of the file see below output clearly for details.)   
                //previous line is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07   
                   
                bufferedReader.mark(0);                                      // marks the beginning of the line   
                for(int j=0;j<1;j++){                                           // j<1 since we have only one junk character.   
                  int k = bufferedReader.read();                            //read the first character.   
                  System.out.println("k is "+k);                            // k is coming as 49(integer value) for charValue(1) which is not a junk character but as we see line is having junk character. ?    
                }                                                                       // k is not displaying -17(integer value) for charValue(?)   
  
  
Please advice on this now. I did as u suggested...what is wrong now....     
  
    
output is   
-----------------------------------------------------------------------------   
  
previous line is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07  
k is 49                // which is not a junk character as see below.   
Byte fileArray Length is 68  
fileArray[0] =   -17 :  HEX=(0xef) :  charValue=(?)   
fileArray[1] =   -69 :  HEX=(0xbb) :  charValue=(?)   
fileArray[2] =   -65 :  HEX=(0xbf) :  charValue=(?)   
fileArray[3] =  49 :  HEX=(0x31) :  charValue=(1)   
  
-----------------------------------------------------------------------------

[Henry Wong]

Even the code in my previous post is doing the same steps.( as you have suggested)(junk character is @ beginning of file)

Huh?!?!?

mark() the beginning of the file,

You didn't do this. At least, not correctly...

then read() the first three characters

You didn't do this.

(not a line, just the first three characters).

You definitely didn't do this. In fact, you did exactly what I said not to do.

If the first three characters are junk characters, then you are done. Simply return the BufferedReader back from the method. If the first three characters are not junk characters, then reset() the buffered reader, and then return it back from the method.

Since, you didn't mark correctly, and you didn't read 3 characters -- you can't do any of these.



Anyway, I don't know what more to say. This may be a language issue. Maybe someone else can explain it better than me...

Henry

[Deepak Lal]

when i read the line it is as below

previous line is ?1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07

//hence there is one junk character now(we dont have 3 junk characters now.)

so i did the below

bufferedReader.mark(0) ; //Marks the present position in the stream hence i have marked as Zero. now what is wrong with this statement.

The BufferedReader API

mark

public void mark(int readAheadLimit)
throws IOException
Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point.

Overrides:
mark in class Reader
Parameters:
readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. An attempt to reset the stream after reading characters up to this limit or beyond may fail. A limit value larger than the size of the input buffer will cause a new buffer to be allocated whose size is no smaller than limit. Therefore large values should be used with care.
Throws:
IllegalArgumentException - If readAheadLimit is < 0
IOException - If an I/O error occurs

Next Step: Since there is only one junk character,im reading a single character

int k = bufferedReader.read(); // Reads a single character. hence im reading a single character see api below

BufferedReader Api says:

read
public int read()
throws IOException
Reads a single character.

Overrides:
read in class Reader
Returns:
The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached
Throws:
IOException - If an I/O error occurs

System.out.println("k is "+k); //here k is displaying the value as 49 which is charValue(1) which is not a junk character but we see line is having a junk character.

Please tell me where i have gone wrong now....

[K. Tsang]

Hello Deepak, having looking through your posts in detail. Have you consider your way of approach using RandomAccessFile readUTF() method. I think this may make life easier. Rather than BufferReader stuff.

[Henry Wong]

bufferedReader.mark(0) ; //Marks the present position in the stream hence i have marked as Zero. now what is wrong with this statement.

The parameter to the mark() method is not the position to mark -- the position to mark is the present position. In fact, passing a zero as the first parameter should effectively disable the marking mechanism.

Henry

[Henry Wong]

Next Step: Since there is only one junk character,im reading a single character

int k = bufferedReader.read(); // Reads a single character. hence im reading a single character see api below

Actually, it is three junk characters -- as shown by your other output. It is just that the string output shows it as one question mark.

Regardless, you didn't read one character or three characters. You read one line AND one character.

Henry

[Henry Wong]

System.out.println("k is "+k); //here k is displaying the value as 49 which is charValue(1) which is not a junk character but we see line is having a junk character.

Please tell me where i have gone wrong now....

It is not a junk character, because you read the junk character off already -- when you read the first line eariler.

Henry

[Henry Wong]

K. Tsang wrote:Hello Deepak, having looking through your posts in detail. Have you consider your way of approach using RandomAccessFile readUTF() method. I think this may make life easier. Rather than BufferReader stuff.

Unfortunately, the OP is very particular in returning a BufferedReader. I am guess it is because this code will be called by some other code that expects a BufferedReader and can't be changed.

As a side note, of all the suggestions so far, I still like the first one the best -- writing a FilteredReader that can wrapped by the Buffered reader (that removes all the illegal chars automatically). It's definitely the most elegant, IMHO.

Henry

[Deepak Lal]

Henry ,
Please what parameter should i pass to my mark method in this scenario...could you correct that and i will proceed further...
Im confused.

[Henry Wong]

Deepak Lal wrote: Please what parameter should i pass to my mark method in this scenario...could you correct that and i will proceed further...
Im confused.

I think you have the misconception that the mark() method will move the position to a certain location in the stream -- it doesn't. It is the reset() method that moves the position. The mark() method just marks the current position.

So, if you want to mark the beginning of the stream, you have to mark it when you are at the beginning of the stream.

I am assuming you want to read a line from the beginning, then go back to the beginning and read a few bytes. To do that, you must mark it, when it is at the beginning, which is before you read the line. And when you want to go back to the beginning, you need to call the reset() method.

As for the parameter to the mark method, that is the number of bytes to buffer -- meaning the number of bytes that you are expecting to read before you call the reset() method. You have to make sure that this number is large enough, or you won't be able to reset. In your example, you need to have enough room to hold the line you are reading and will later reset.

Henry

[Campbell Ritchie]

Too difficult a quesiton for "beginners". Moving.

[Martijn Verburg]

Also for those interested, reading this is highly recommended.

[Deepak Lal]

Hi Henry,
Could you please paste the code which could help me to achieve the impossible.i have been struggling to get ghis done....please

[Henry Wong]

Deepak Lal wrote:Hi Henry,
Could you please paste the code which could help me to achieve the impossible.i have been struggling to get ghis done....please

Nope. Still not a code mill.

No offense intended. But I gave you three possible solutions. You completely ignored the first two. And with this last one, which I completely described you the solution -- enough that it can be considered pseudo code, you did something only remotely related. Complained that you did it correctly. And when I explain that you didn't, and gave you clarification, you are now ignoring the clarification and blatently asking for the solution.

Sorry, but since you have little interest in doing this yourself, there is no longer a need for me here.

Henry

[Henry Wong]

As for this...

As a side note, of all the suggestions so far, I still like the first one the best -- writing a FilteredReader that can wrapped by the Buffered reader (that removes all the illegal chars automatically). It's definitely the most elegant, IMHO.

It was pretty straightforward. It took me 20 minutes to write the FilterReader.

Henry

[Deepak Lal]

You have to make sure that this number is large enough, or you won't be able to reset. In your example, you need to have enough room to hold the line you are reading and will later reset.

this number is large enough. can you atleast tell me large enough means what could be the value.

example if there are 300 lines,then approximately
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07

upto 300 lines.

please suggest... im

[Deepak Lal]

Hi Henry,
Need your help again...Please ....

 
                bufferedReader.mark(2*1024);
                 for(int k=1;k<=3;k++){
                	 System.out.println("The value of k "+bufferedReader.read());
                 }

                  But still im getting the below o/p...
         ---------------------------------------------------------
                       The value of k 65279
                       The value of k 49
                       The value of k 48    
          ---------------------------------------------------------
               

Could you please tell me where i have gone wrong now...im reading the first 3 characters...isnt that correct,,,could you please refine the above code

[Paul Clapham]

(I haven't been following this thread, so my apologies if this has already been covered.)

So okay, you read those three characters from the Reader. You seem to think you have "gone wrong" in some way. But I don't see a problem. What do you see as the problem with that code?

[Deepak Lal]

i should get 3 junk characters,but now im getting as below
{
The value of k 65279 (what is this referring to)
The value of k 49 which is correct for charValue(1)
The value of k 48 which is correct for charValue(0)
}
where are the three junk characters as referred by Henry. ??? or is this the correct output code ???

Please help me im still confused.

Deepak

[Henry Wong]

this number is large enough. can you atleast tell me large enough means what could be the value.

example if there are 300 lines,then approximately
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07
1001528770;PHP;ABQ;PHP;22;SHA;123456789;Tan Ya Ling;26:11:2008;07

upto 300 lines.

Since you only intend to reset, at most 3 characters, then shouldn't a value of 3 be okay?

Henry