String & byte
Hello everybody,
I'm in this situation: I have a byte array initialized by a list of integers. For some reason, my goal is to convert it to a String and then to get those integers.
I wrote this simple code:
byte b[] = { -38, -127, -53, -52, 87, 40, -50, -44, -53, 87, -56, -52, 63, 81, 0, -56, 76, -84, 2, 0, 43, -120, 5, -5 };
String s = new String(b);
byte b2[] = s.getBytes();
for(int i=0; i<b2.length; i++)
System.out.println((int)(b2));
but, it works with all ingers except -127, in facts it displays -127 as 63!
How can I solve this problem? Thanks!
BalusC wrote:
I tried ISO-8859-1 here and it worked.
byte[] bytes = { -38, -127, -53, -52, 87, 40, -50, -44, -53, 87, -56, -52, 63, 81, 0, -56, 76, -84, 2, 0, 43, -120, 5, -5 };
String string = new String(bytes, "ISO-8859-1");
for (byte b : string.getBytes("ISO-8859-1")) {
System.out.print(b + " ");
All the ISOs 'work' but the point is - what it the OP trying to do?
Similar Messages
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Memory leak in String(byte[] bytes, int offset, int length)
Has anyone run into memory leak problem using this String(byte[] bytes, int offset, int length) class? I am using it to convert byte array to string, and I am showing memory leak using this class. Any idea what is going on?
Hi,
If you post in Native methods forum I assume you are using this constructor in the native side.
Be aware that getting char * from jstring eats memory that you must free before returning from native with env->ReleaseStringUTFChars().
--Marc (http://jnative.sf.net) -
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Thanks.This is beginning to make a little sense. The problem is that you got a String and you don't want one. A String wraps an array of chars, which your app needs, right? Specifically they're chars because you need 16-bit char sets.
Presumably the getBytes() method call is used to get an array of bytes for some data transfer operation. java.nio was probably added in 1.4 as it has some very efficient ways of handling buffers as simultaneously of two or more types. It's trying to use the underlying char array as a byte array and there's a straight up bug someplace.
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Strings, byte[]s, and encoding ....
I'm realising I really don't know anything of the java encoding fonctionnalities ...
For example: I' ve written amethod String encode(String) which transforms a bytecode (I hope parameter's byecode) in an other bytecode (I hope result's bytecoed). This transformation is done with a special Charset that I've built. And I use Charset.encode(String).
I've try to call this method with two String parameters. These two String give the same result when calling System.out.println(....) and String.getBytes(). But the two results of my method's call with these two parameters are different !!!!!! How is it possible ?????
There a lot of things I don't know. For example:
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Thank's for any help.I've try to call this method with two String
parameters. These two String give the same result when
calling System.out.println(....) and
String.getBytes(). But the two results of my method's
call with these two parameters are different !!!!!!
How is it possible ?????You used getBytes(String charsetName) with a set of characters that included both overlapping and non-overlapping characters? -
hi everyone,
i have a bunch of hexadecimal code which is read from a text file into a String.
i want to put this String into a byte array without changing anything.
my algorithm is like this -
String strFromTextFile = "FFD8FFE0001";
* put strFromTextFile into byteArr[ ]
byteArr[0] == 'F';
byteArr[1] == 'F';
byteArr[2] == 'D';hi, i think this simple code will fulfill ur need
public class hex {
public static void main(String[] args) {
String str= "AFFD8FFE0001";
byte hexbytes[] = hexstore(str);
public static byte[] hexstore(String str)
int length = str.length();
if((length%2)!=0)
length++;
str = new String(str+"0");
byte[] a = new byte[length/2];
for(int i=0,j=0;i<str.length();i=i+2,j++)
byte c =(byte) str.charAt(i);
if(c<65)
c= (byte)((int)c-48);
else
c= (byte)(10+(int)c-65);
c=(byte)((int)c<<4);
byte d =(byte) str.charAt(i+1);
if(d<65)
d= (byte)((int)d-48);
else
d= (byte)(10+(int)d-65);
c = (byte)(c | d);
a[j]=c;
for(int i=0;i<length/2;i++)
System.out.println("byte "+((int)a));
return a;
example ( for first 2 characters)
AF has to be stored as 1010 1111
1010 1111 is stoted in a[0]; -
Hi
I'm basically trying to simulate DES in java from scratch (so no use of existing API's or anything). I've got a basic idea of how DES works (use of a feistel cipher).
So to start off I'm trying to get the bytes of a string with this simple program:
public class Test {
public static void main(String[] args) {
String testString = "hello";
System.out.println(testString.getBytes());
}The output consists of some characters (namely numbers, letters and 1 special character).
But when I change the variable testString to some other String, complie and run I still get the same output even though the String is different. Also why are there 9 characters for a String thats only 5 characters long?
ThanksWhen you use System.out.println( something ) it uses to the toString() method of the object referenced by 'something'. When the something is an array such as an array of bytes the toString() methed returns a pseudo reference to the array which in no way reflects the content of the array.
If you just want to see the content of the array then use Arrays.toString(something) to generate a String representation of the content of the array.
Also, the use of String.getBytes() will convert the String to bytes using your default character encoding. This is rarely what you want since the result may depend on which platform you are working on. In my view, the safest and best approach is to explicitly define the encoding and since it will encode ALL characters one can throw at it I always use utf-8. So, to convert a String to bytes I would usebyte[] bytesOfString = "your string".getBytes("utf-8");and to convert them back to a String I would useString yourString = new String(bytesOfString,"utf-8");One final point, do not assume that an apparently random array of bytes such as one gets from DES encryption can be converted to a String using the above. In general it can't because not all bytes and byte sequences are valid for a particular character encoding. If you absolutely have to have a String representation then you should encode (not encrypt) the bytes using something like Base64 or Hex encoding.
Edited by: sabre150 on Jan 27, 2008 3:04 PM -
New String(byte[]) taking up huge space?
Ok. I have a byte[] of approx. 5.000.000 bytes. Whenever, at any point, I try to create a String using this array by new String(array), my memoryusage increases by about 60/65 megabytes. Can anyone please explain me why on earth it's doing this?
Note also that this space is not freed up by the GC (afterwards).
Thanks in advanceActually, I've discovered some details about the swing textcomponents. They're very bad for 'simply' showing 2mb+ files.
Check out these bugs; original and "more recent".
It doesn't quite explain why putting a byte array to a string occupies twice the space, but it does seem to account for the huge memory increase when putting it to a JTextArea.
String is immutable so it has to copy your char[] to
a new char[] backing the String. If it used theSure thing, but I'm passing on a byte[] array, and afaik, it's not using this array and should only copy it. Once.
Oh hey, could it be that the bytes are saved in unicode? That would double the size... and make sense...
Oh and PS; Maybe you should read this if you really think strings are immutable... (although you are generally correct :)) -
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Reading serial port...
44,44,52,46,50,44,77,44,45,51,52,46,50,44,77,44,44,48,48,48,48,42,120,30,-104,-128,96,120,96,0,-26,126,-98,-104,-98,0,30,-122,6,30,-122,6,120,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,120,-122,-32,-122,-32,-122,-32,-122,-104,-122,6,120,6,-98,30,-104,-128,96,120,96,0,-26,24,-26,-26,-104,30,30,-122,24,120,-32,120,30,102,120,-26,120,-26,-4,48,50,52,44,86,44,52,48,53,54,46,49,50,50,49,44,78,44,48,55,51,53,52,38,54,70,70,-58,118,-115,25,25,89,70,6,102,6,-122,-58,-58,-58,-26,83,102,-122,
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36,71,80,71,71,65,44,50,49,52,53,53,54,46,48,50,52,44,52,48,53,54,46,49,50,50,49,44,78,44,48,55,51,53,52,46,50,51,52,52,44,87,44,48,44,48,48,44,44,52,46,50,44,77,44,45,51,52,46,50,44,77,44,44,48,48,48,48,42,52,66,13,10,36,71,80,71,83,
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Reading serial port...
$GPGGA,214724.031,4056.1221,N,07354.2344,W,0,00,,4.2,M,-34.2,M,,0000*48
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,11,31,70,286,,14,57,089,,32,51,293,,30,44,061,*7D
$GPGSV,3,2,11,05,24,046,,22,23,167,,20,20,315,,16,15,194,*70
$GPGSV,3,3,11,12,12,039,,29,09,103,,11,00,279,*4F
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$GPGSA,A,1,,,,,,,,,,,,,,,*1ENow those are the NMEA sentences that the GPS receiver spits out, that's exactly what I need. Only problem is I'm printing them out using the following code:
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while (canRead()) // Loop
int bytesRead = theInput.read(buffer);
if (bytesRead == -1)
break;
for (int z = 0; z < bytesRead; z++)
System.out.print(Character.toString((char)buffer[z]));
}So as you can see, it's simply taking the byte, converting it from ASCII to a symbol or letter, and putting it on the screen. Then it moves onto the next byte. So what I've tried to do is change it again so that it adds each converted letter to a string value, starting a completely new string every time it hits a $ sign, which always starts a NMEA sentence:
byte[] buffer = new byte[4096];
InputStream theInput = thePort.getInputStream();
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while (canRead()) // Loop
int bytesRead = theInput.read(buffer);
if (bytesRead == -1)
break;
String s = "";
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if (Character.toString((char)buffer[z]).equalsIgnoreCase("$") && s.length() > 1)
System.out.println(s);
s = Character.toString((char)buffer[z]);
else
s = s + Character.toString((char)buffer[z]);
// System.out.print(Character.toString((char)buffer[z]));
s = "";
}The problem with this is for some reason the sentences aren't whole, there's line breaks inserted into them. So when I'm passing them to the parser, I'm passing incomplete sentences. Here's the output I'm getting now:
Reading serial port...
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
.2,M,-34.2,M,,0000*4D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
,32,51,293,,30,44,061,*7D
$GPGSV,3,3,11,12,12,039,,29,09,103,,11,00,279,*4FHow do I get each NMEA sentence into a string so I can send it to a parser? Any ideas?
Edited by: DeX on Jun 14, 2008 6:02 PMYour problem is that you're assuming a newline actually indicates the end of a line.
Assuming you can't fix the sender (or yell at the maintainer and get him to fix it), take
advantage of the fact that you know what a valid line starts with and just ignore the newline
characters.
Thanks but that gives me the same result. I think my issue is with the multithreading,
another thread is rolling through and assigning values to the String before the previous
thread is finished copying the bytes to it. I suggest you take advantage of the StringBuilder class. Also, if you insist on using the
String(byte[ ]) constructor, you should note that you're assuming a charset, a rather
dangerous thing to do. Use the String(byte[ ], String) constructor instead and explicitly use US-ASCII. -
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Writer out = new BufferedWriter(new OutputStreamWriter(new ByteArrayOutputStream()));
out.write(v);
byte[] b = v.getBytes());
Thanks!Ok, that was a mess - take 2:
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http://java.sun.com/j2se/1.4.1/docs/api/java/lang/String.html#constructor_summary
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String(byte[] ascii, int hibyte)
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How to save a value in a byte array, retrieve it and display it?
Hi,
I am doing a project for my data structures class that involves saving a value (given in String format) in a byte array (our 'memory'). Initially I just tried casting character by character into the byte array and casting back to char[] for retrieval (using .toString() to return what's supposed to be the original string), but this did not work. I tried the .getBytes() method, applying it to the string and then trying to recover it by placing the contents of the 'memory' in a byte array and applying toString(), but that didn't work either. I looked a bit and found this class, CharsetEncoder and CharsetDecoder. I tried to use these but when I try the compiler tells me I cannot instantiate CharsetDecoder because it is an abstract class. At this point I'm at a loss as to what I can do. Is there any way to place a string in a byte array and then recover the string in it's original format? For example, I might save a value in my particular class of "456". But when I try to recover the value from my 'memory' i.e. the byte array, it comes out like [gnue@hnju.... or something similar. I need it to output the original string ("456").
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return bytes.toString();You can certainly put it into a byte array and then construct a new String from that byte array. Just calling toString doesn't mean you'll automatically get a meaningful string out of it. Arrays do not override the toString method, so the use the one inherited from object.
Look at String's constructors. -
JCO.Server appends null character to string
I am a complete SAP and JCO newbie so I'll try making as much since as I can, given the fact that I'm not familiar with SAP terminology and technology. I've been lent as a developer to another group which needs a legacy application rewritten. The application processes a RFC and decrypts the RFC encrypted payload and returns it along with a status code.
I have made progress - I'm able to register my server with the SAP runtime and using the SAP GUI application and the help of a SAP developer, I'm able to make an RFC call to my application. I'm able to read the parameters sent from SAP and write parameters back.
The problem is that one of the parameters I'm writing back (java.lang.String) appears to have and extra character on SAP side. On the GUI it appears as a '#' (pound) sign. The SAP developer told me the string is terminated with a null character which I know is a C/C++ thing but not a Java thing. I don't think it is a Unicode issue. The Java server is not running in Unicode mode and any attempt to set the jco.server.unicode property (I may have forgotten the exact name) to a value of 1 causes the RFC to fail.
I think the issue is likely to be the manner in which I defined the function parameters or the manner in which I write them. The following are code snippets:
Defining the function:
JCO.MetaData metadata = new JCO.MetaData(Constants.FUNCTION_DECRYPT);
metadata.addInfo(Constants.PARAMETER_SCHEME, JCO.TYPE_INT, 255, 0, 0, JCO.IMPORT_PARAMETER, null);
metadata.addInfo(Constants.PARAMETER_ENCRYPTED, JCO.TYPE_STRING, 255, 0, 0, JCO.IMPORT_PARAMETER, null);
metadata.addInfo(Constants.PARAMETER_DECRYPTED, JCO.TYPE_STRING, 255, 0, 0, JCO.EXPORT_PARAMETER, null);
metadata.addInfo(Constants.PARAMETER_RETURN_CODE, JCO.TYPE_INT, 255, 0, 0, JCO.EXPORT_PARAMETER, null);
Server request handling code:
protected void handleRequest(JCO.Function function)
// Obtaining import/export parameter lists.
JCO.ParameterList input = function.getImportParameterList();
JCO.ParameterList output = function.getExportParameterList();
// Getting scheme and encrypted text parameters.
int scheme = input.getInt(Constants.PARAMETER_SCHEME);
String encrypted = input.getString(Constants.PARAMETER_ENCRYPTED);
// Decoding base 64 string.
byte[] bytes = Base64.decode(encrypted);
// Obtaining cipher by scheme and decrypting the text.
AppCipher cipher = ApplicationConfiguration.getDecryptor(scheme);
if(cipher == null)
logger.error("Unable to get cipher due to an unknown encryption scheme: " + scheme);
else
byte[] decrypted = cipher.decrypt(bytes);
String plainText = new String(decrypted);
// Setting decrypted value information and return code.
output.setValue(plainText, Constants.PARAMETER_DECRYPTED);
output.setValue(Constants.RETURN_CODE_SUCCESS, Constants.PARAMETER_RETURN_CODE);I seem to have made progress. If I define the parameter type as JCO.TYPE_CHAR instead of JCO.TYPE_STRING, it works:
metadata.addInfo(Constants.PARAMETER_DECRYPTED, JCO.TYPE_CHAR, 255, 0, 0, JCO.EXPORT_PARAMETER, null);
That is the only change I made. I'm still setting the parameter value as java.lang.String. I hope this won't cause issues elsewhere. I was also able to change the field definition and set it as a byte array. However, that had the problem of having to define the exact length of the byte array in the field metadata otherwise the remaining bytes would appear as null bytes on SAP side. -
i have a byte[] which I have got from DB. I want to convert it into a object before returning it from a method. There is a wraaper class for byte i.e. Byte. But I am not sure tha how to convert a byte[] into an Object.
Thanks!!georgexu316 wrote:
corlettk wrote:
georgexu316 wrote:
If you know what you are doing, you can perform an implicit conversion by casting the byte.
byte byteData = new byte();
Object newObj = (Object) byteData;
Umm.. Dude, a byte array is-an Object. In Java you don't ever need to explicitly up-cast... but (in order to actually use it as a byte array) you do have to explicitly down-cast it.
For example:
package forums;
class AByteArrayIsAnObject
public static void main(String[] args) {
try {
Object bytes = "Hello World!".getBytes(); // returns a reference to a newly created byte-array-object
System.out.println( new String((byte[])bytes) );
} catch (Exception e) {
e.printStackTrace();
Well, the person asked to convert it into an Object, maybe he needs it as a object to pass it through another parameter of another method. Even though byte is an extension of Object and you can use all of Object's methods, it wouldn't pass through a parameter of a method that specifies an object.Ummm... Wanna bet?
package forums;
class AByteArrayIsAnObjectTest
public static void main(String[] args) {
try {
println(new String((byte[])getBytes("Hello World!")));
} catch (Exception e) {
e.printStackTrace();
private static Object getBytes(String s) {
return s.getBytes();
private static void println(Object o) {
System.out.println(String.valueOf(o));
}
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