Class Object into Byte Array

Is there a way to copy a class object into a byte array? If so, how?

hi check out
http://forum.java.sun.com/thread.jspa?threadID=562268&
messageID=2766098This does not work in j2me. WriteObject does not exist, and there are no serialsation interfaces in j2me. So you'll have to do that on your own.
look here: http://java.sun.com/developer/J2METechTips/2002/tt0226.html

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How can i convert object to byte array very*100 fast?

i need to transfer a object by datagram packet in embeded system.
i make a code fallowing sequence.
1) convert object to byte array ( i append object attribute to byte[] sequencailly )
2) send the byte array by datagram packet ( by JNI )
but, it's not satisfied my requirement.
it must be finished in 1ms.
but, converting is spending 2ms.
network speed is not bottleneck. ( transfer time is 0.3ms and packet size is 4096 bytes )
Using ObjectOutputStream is very slow, so i'm using this way.
is there antoher way? or how can i improve?
Edited by: JongpilKim on May 17, 2009 10:48 PM
Edited by: JongpilKim on May 17, 2009 10:51 PM
Edited by: JongpilKim on May 17, 2009 10:53 PM

thanks a lot for your reply.
now, i use udp socket for communication, but, i must use hardware pci communication later.
so, i wrap the communication logic to use jni.
for convert a object to byte array,
i used ObjectInputStream before, but it was so slow.
so, i change the implementation to use byte array directly, like ByteBuffer.
ex)
public class ByteArrayHelper {
private byte[] buf = new byte[1024];
int idx = 0;
public void putInt(int val){
buf[idx++] = (byte)(val & 0xff);
buf[idx++] = (byte)((val>>8) & 0xff);
buf[idx++] = (byte)((val>>16) & 0xff);
buf[idx++] = (byte)((val>>24) & 0xff);
public void putDouble(double val){ .... }
public void putFloat(float val){ ... }
public byte[] toByteArray(){ return this.buf; }
public class PacketData {
priavte int a;
private int b;
public byte[] getByteArray(){
ByteArrayHelper helper = new ByteArrayHelper();
helper.putInt(a);
helper.putInt(b);
return helper.toByteArray();
but, it's not enough.
is there another way to send a object data?
in java language, i can't access memory directly.
in c language, if i use struct, i can send struct data to copy memory by socket and it's very fast.
Edited by: JongpilKim on May 18, 2009 5:26 PM

Create Class objects from an Array of File Objects

Hi There,
I'm having extreme difficulty in trying to convert an array of file objects to Class objects. My problem is as follows: I'm using Jfilechooser to select a directory and get an array of files of which are all .class files. I want to create Class objects from these .class files. Therefore, i can extract all the constructor, method and field information. I eventually want this class information to display in a JTree. Very similar to the explorer used in Netbeans. I've already created some code below, but it seems to be throwing a NoSuchMethodError exception. Can anyone please help??
Thanks in advance,
Vikash
/* the following is the class im using */
class FileClassLoader extends ClassLoader {
private File file;
public FileClassLoader (File ff) {
this.file = ff;
protected synchronized Class loadClass() throws ClassNotFoundException {
Class c = null;
try {
// Get size of class file
int size = (int)file.length();
// Reserve space to read
byte buff[] = new byte[size];
// Get stream to read from
FileInputStream fis = new FileInputStream(file);
DataInputStream dis = new DataInputStream (fis);
// Read in data
dis.readFully (buff);
// close stream
dis.close();
// get class name and remove ".class"
String classname = null;
String filename = file.getName();
int i = filename.lastIndexOf('.');
if(i>0 && i<filename.length()-1) {
classname = filename.substring(0,i);
// create class object from bytes
c = defineClass (classname, buff, 0, buff.length);
resolveClass (c);
} catch (java.io.IOException e) {
e.printStackTrace();
return c;
} // end of method loadClass
} // end of class FileClassLoader
/* The above class is used in the following button action in my gui */
/* At the moment im trying to output the data to standard output */
private void SelectPackage_but2ActionPerformed(java.awt.event.ActionEvent evt) {
final JFileChooser f = new JFileChooser();
f.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
int rVal = f.showOpenDialog(Remedy.this);
// selects directory
File dir = f.getSelectedFile();
// gets a list of files within the directory
File[] allfiles = dir.listFiles();
// for loop to filter out all the .class files
for (int k=0; k < allfiles.length; k++) {
if (allfiles[k].getName().endsWith(".class")) {
try {
System.out.println("File name: " + allfiles[k].getName()); // used for debugging
FileClassLoader loader = new FileClassLoader(allfiles[k]);
Class cl = loader.loadClass();
//Class cl = null;
Class[] interfaces = cl.getInterfaces();
java.lang.reflect.Method[] methods = cl.getDeclaredMethods();
java.lang.reflect.Field[] fields = cl.getDeclaredFields();
System.out.println("Class Name: " + cl.getName());
//print out methods
for (int m=0; m < methods.length; m++) {
System.out.println("Method: " + methods[m].getName());
// print out fields
for (int fld=0; fld < fields.length; fld++) {
System.out.println("Field: " + fields[fld].getName());
} catch (Exception e) {
e.printStackTrace();
} // end of if loop
} // end of for loop
packageName2.setText(dir.getPath());
}

It's throwing the exeption on the line:
FileClassLoader loader = new FileClassLoader(allfiles[k]);
I'm sure its something to do with the extended class i've created. but i cant seem to figure it out..
Thanks if you can figure it out

How to convert a Image object to byte Array?

Who can tell me, how to convert Image object to byte Array?
Example:
public byte[] convertImage(Image img) {
byte[] b = new byte...........
return b;

Hello,
any way would suit me, I just need a way to convert Image or BufferedImage to a byte[], so that I can save them. Actually I need to save both jpg and gif files without using any 3rd party classes. Please help me out.
thanx and best wishes

Putting a Class Object into a Vector

HI all
I need to put a class object into another classes vector, then be able to read it and retrieve data.
I can put the object into the vector but all i seem to be able to retrieve is data like Account@2343c2.
Is this some sort of tag? How do i get to the data?
thankz
joey

That's what you get when you print an object which does not have its own toString() method to do anything different - it picks up the Object class's toString method instead. For example:
System.out.println(new Object());It sounds like you're doing something like this:
Vector v = new Vector();
v.add(new Account(42));If you were to do the following, you would see that sort of output:
System.out.println(v.get(0));The appropriate way to do this would be something like the following:
   // Use a List reference instead of a Vector reference, and create
   // an ArrayList object in preference to a Vector object
   List list = new ArrayList();
   list.add(new Account(42));
   // Iterate through the list of accounts - use an
   // iterator because this prevents off-by-one errors
   // that arise with direct indexing.
   Iterator i = list.iterator();
   while(i.hasNext()) {
      // Cast the reference returned by the iterator from
      // Object to Account so that we can call account-specific
      // methods.
      Account current = (Account)i.next();
      // Call the method specific to the Account class (getBalance
      // is just an example that I made up).
      System.out.println(current.getBalance());
   }

Converting image into byte array

Hi all,
How to convert an integer array image into byte array ?
here i have a image like this :
private static int pixelArray[] = {
0xff000000, 0xff000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000,
0xff000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000
From this one i create image like this one :
Image image = Image.createRGBImage(pixelArray, width, height, true);
Now i want to convert that pixelArray into byte array ? how to do this
additionally i want to send this byte array to servlet .
thanks in advance.

Hi,
If you want to convert your int array to a byte array you should
split each integer into 4 bytes to avoid losing information. You can
rebuild your integer array later if you need to. I think this code
will work (i havent tested it):
byte[] pixel= new byte[pixelArray.length<< 2];
for (int i= pixelArray.length- 1; i>= 0; i--) {
int aux= i<< 2; // i* 4 = i<< 2
pixel[aux]= (byte) (pixelArray>> 32);
pixel[aux+ 1]= (byte) (pixelArray[i]>>> 16);
pixel[aux+ 2]= (byte) (pixelArray[i]>>> 8);
pixel[aux+ 3]= (byte) pixelArray[i];
Greets.

How do I read directly from file into byte array

I am reading an image from a file into a BuffertedImage then writing it out again into an array of bytes which I store and use later on in the program. Currently Im doing this in two stages is there a way to do it it one go to speed things up.
try
            //Read File Contents into a Buffered Image
            /** BUG 4705399: There was a problem with some jpegs taking ages to load turns out to be
             * (at least partially) a problem with non-standard colour models, which is why we set the
             * destination colour model. The side effect should be standard colour model in subsequent reading.
            BufferedImage bi = null;
            ImageReader ir = null;
            ImageInputStream stream = ImageIO.createImageInputStream(new File(path));
            final Iterator i = ImageIO.getImageReaders(stream);
            if (i.hasNext())
                ir = (ImageReader) i.next();
                ir.setInput(stream);
                ImageReadParam param = ir.getDefaultReadParam();
                ImageTypeSpecifier typeToUse = null;
                for (Iterator i2 = ir.getImageTypes(0); i2.hasNext();)
                    ImageTypeSpecifier type = (ImageTypeSpecifier) i2.next();
                    if (type.getColorModel().getColorSpace().isCS_sRGB())
                        typeToUse = type;
                if (typeToUse != null)
                    param.setDestinationType(typeToUse);
                bi = ir.read(0, param);
                //ir.dispose(); seem to reference this in write
                //stream.close();
            //Write Buffered Image to Byte ArrayOutput Stream
            if (bi != null)
                //Convert to byte array
                final ByteArrayOutputStream output = new ByteArrayOutputStream();
                //Try and find corresponding writer for reader but if not possible
                //we use JPG (which is always installed) instead.
                final ImageWriter iw = ImageIO.getImageWriter(ir);
                if (iw != null)
                    if (ImageIO.write(bi, ir.getFormatName(), new DataOutputStream(output)) == false)
                        MainWindow.logger.warning("Unable to Write Image");
                else
                    if (ImageIO.write(bi, "JPG", new DataOutputStream(output)) == false)
                        MainWindow.logger.warning("Warning Unable to Write Image as JPEG");
                //Add to image list
                final byte[] imageData = output.toByteArray();
                Images.addImage(imageData);


If you don't need to manipulate the image in any way I would suggest you just read the image file directly into a byte array (without ImageReader) and then create the BufferedImage from that byte array.

Putting integer value of 163 into byte array

I have an integer value of 163. I need to put that into a byte array. When i do, it puts it as -93. Whats wrong? and how can i put it in correctly?

Hi,
You cannot store 163 in a byte variable. In Java a byte variable will have only 8 bits and its value range will be from -128 to +127. In a byte variable you cannot store a value which is out of this range. If you try to cast an integer value which is out of this range to byte then you will get unexpected results (But you can find what the result will be).

How do I convert an Object into an Array?

If I have an instance of type object that I know is really a DataGrid row that was cast into an object when passed to a function, how can I cast that Object to an array, such that each index of this array would correspond to the information in a given column of the row?

@Sathyamoorthi
Can you please explain what this function does? Essentially, what should be contained in the String?
I printed out the string and it seems like I am getting a random row in the Object, as opposed to first or last. Why is that?
UPDATE: I printed out the value of dataGrid0.columns[5].dataField but it just turned out to be the id of the column.

What is the best way to convert a cluster into byte array or string

I'm writing a program that sends UDP packets and I've defined the data I want to send via large clusters (with u8/u16/u32 numbers, u8/u16/u32 arrays, and nested clusters). Right before sending the data, I need to convert the clusters either into strings or byte arrays. The flatten to string function is almost perfect for this purpose. However, it's appending lengths to arrays and strings which renders this method useless, as far as I can tell.
As I have many of these clusters, I would rather not hard code the unbundle by names and converting/typecasting to byte arrays or strings for each one.
Is there a feature or tool I am overlooking?
Thank you!

deceased wrote:
Flatten to string has a boolean input of "Prepend string or array size" ... The default value is true.
That only specifies if a string or array size should be prepended if the outermost data element is a string or array. For embedded strings or arrays it has no influence. This is needed for the Unflatten to be able to reconstruct the size of the embedded strings and arrays.
The choice to represent the "Strings" (and Arrays) in the external protocol to LabVIEW strings (and arrays) is actually a pretty bad one unless there is some other element in the cluster that does define the length of the string. An external protocol always needs some means to determine how long the embedded string or array would be in order to decode the subsequent elements that follow correctly.
Possible choices here are therefore:
1) some explicit length in the protocol (usually prepended to the actual string or array)
2) a terminating NULL character for strings, (not very friendly for reliable protocol parsing)
3) A fixed size array or string
For number 1) and 2) you would always need to do some special processing unless the protocol happens to use explicitedly 32 bit integer length indicators directly prepended before the variable sized that.
For number 3) the best representation in LabVIEW is actually a cluster with as many elements inside as the fixed size.

Conversion of image into byte array

I have a problem in converting .png image into bytestream, if anyone can help in this pls do so.....

Hi,
To convert an Image to bytes you can use the Image.getRGB() method.
http://java.sun.com/javame/reference/apis/jsr118/javax/microedition/lcdui/Image.html#getRGB(int[], int, int, int, int, int, int)
-Henrik

Reading a pdf file from URL into Byte array/ByteBuffer in an applet.

I'm trying to figure out why this particular snippet of code isn't working for me. I've got an applet which is supposed to read a .pdf and display it with a pdf-renderer library, but for some reason when I read in the .pdf files which sit on my server, they end up as being corrupt. I've tested it by writing the files back out again.
I've tried viewing the applet in both IE and Firefox and the corrupt files occur. Funny thing is, when I trying viewing the applet in Safari (for Windows), the file is actually fine! I understand the JVM might be different, but I am still lost. I've compiled in Java 1.5. JVMs are 1.6. The snippet which reads the file is below.
public static ByteBuffer getAsByteArray(URL url) throws IOException {
        ByteArrayOutputStream tmpOut = new ByteArrayOutputStream();
        URLConnection connection = url.openConnection();
        int contentLength = connection.getContentLength();
        InputStream in = url.openStream();
        byte[] buf = new byte[512];
        int len;
        while (true) {
            len = in.read(buf);
            if (len == -1) {
                break;
            tmpOut.write(buf, 0, len);
        tmpOut.close();
        ByteBuffer bb = ByteBuffer.wrap(tmpOut.toByteArray(), 0,
                                        tmpOut.size());
        //Lines below used to test if file is corrupt
        //FileOutputStream fos = new FileOutputStream("C:\\abc.pdf");
        //fos.write(tmpOut.toByteArray());
        return bb;
}I must be missing something, and I've been banging my head trying to figure it out. Any help is greatly appreciated. Thanks.

Keshav.. wrote:
I too was going through the same problem but I found for some pdfs it worked fine.I didnt get ur solution.Please explain bcoz it may work for every pdfThis thread is over 3 years old and dead. Please open a new thread which provides details of the problem you are having. Link to this thread if you think it is necessary.
I shall lock this thread.

Insert multiple objects into variable (array)

Hello,
I need to create PS script to which gets logged on users(get-rdusersession | select UserName), puts them into variable $users=@(user1,user2,...,userN) and runs foreach {something} - something like send message and logoff user. But I cannot get the
output from command get-rdusersession to the variable. Can someone tell, how to do that? Thank you.
Pete
sfs

Hi Pete,
try this:
$Users = Get-RDUserSession | Select -ExpandProperty UserName
The "-ExpandProperty" Parameter means the select command returns a String with the value that the UserName property on the output of Get-RDUserSession had. Otherwise you get a PSObject that has a UserName property itself, containing that string
(try Piping both versions to the cmdlet Get-Member and see for yourself, both properties and type name).
Cheers,
Fred
Ps.: Try running Get-RDUserSession in your Powershell Console and check whether you actually get any output, in case that's the problem.
There's no place like 127.0.0.1

How to read an inputStream in UTF-8 into a byte array.

Hi, Java version is 1.4.2. If inputStream.read() is used to read the bytes into a byte array, is it guarenteed that UTF-8 chars are correctly transferred into byte array? Or should we use InputStreamReader? An example would be a great help.
Thanks in advance.

I would like to send a byte array read from InputStream to another app where they are converted to UTF-8. In brief
-Read input stream which comes in UTF-8 into a byte array
-Send byte array to another app which will convert it into UTF-8 characters

How to change the image into byte and byte array into image

now i am developing one project. i want change the image into byte array and then byte array into image.

FileInputStream is = new FileInputStream(file);
byte[] result = IOUtils.toByteArray(is);
with apache common IO lib

Class Object into Byte Array

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