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Editorial Team
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Asked: 2026-05-27T18:38:24+00:00

In Android, I am trying to transfer an XML file, between 2 devices, by

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In Android, I am trying to transfer an XML file, between 2 devices, by opening a socket connection between them. I am able to successfully locate the devices, connect and open socket connection.

The issue is – when i read the xml file that is sent by first device, a lot of junk characters are found inserted in it. For example, the folllwoing XML file sent by a device:

  <?xml version="1.0" encoding="ISO-8859-1" ?> 
  <note>
     <to>Tove</to> 
     <from>Jani</from> 
     <heading>Reminder</heading> 
     <body>Don't forget me this weekend!</body> 
  </note>

is received as follows by the other device:

  ¬íwµ<?xml version="1.0" encoding="ISO-8859-1" ?> 
  <note>
     <to>Tove</to> 
     <from>Jani</from> 
     <heading>Reminder</heading> 
     <body>Don't forget me this weekend!</body> 
  </note>

The junk characters seen in this XML file are inserted at multiple points for a bigger XML file. Here’s the code for reading the XML file on the client:

 InputStream tmpIn = null;
 FileOutputStream fos = null;
 BufferedOutputStream bos = null;
 byte[] buffer = null;
 int current = 0;
 try { 
     tmpIn = socket.getInputStream(); 

        // create a new file
     File newTempFile = new File("/mnt/sdcard/test.xml");
        if(!newTempFile.exists()) {
        newTempFile.createNewFile();
     }
        else {
        newTempFile.delete();
        newTempFile.createNewFile();
     }
    fos = new FileOutputStream(newTempFile);
        try {
        byte[] buffer1 = new byte[2048]; 
        int length; 
        while ((length = tmpIn.read(buffer1))>0){
                fos.write(buffer1, 0, length); 
        } 

       fos.flush();
       fos.close();
       tmpIn.close();

     } 
     catch (IOException e) {
       Log.d("Sync", "IOException: "+ e);
     }
}
catch (Exception e) {
   Log.d("Sync", "Exception: "+ e);
}

Ans here’s the code for writing the XML file:

File file = new File ("/mnt/sdcard/sample.xml");
byte[] fileBytes = new byte[(int) file.length()];

try {
    BluetoothSocket socket = device.createRfcommSocketToServiceRecord(MY_UUID); 
    socket.connect(); 
    ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream()); 

    FileInputStream fis = new FileInputStream(file);
    fis.read(fileBytes);

    // Send the file 
    out.write(fileBytes); 
    out.flush();  
    out.close();
 }
 catch (Exception e) {
       Log.d("Sync", "Exception in writing file: "+ e);
 }

I strongly believe that there is an error with reading the socket input stream on the clinet and creating an XML file from it. Not sure what it is? Am I writing any control characters to the XML file. My belief is further supported by the fact that similar junk characters are found in a larger XML file, at multiple places (perhaps one set for writing one buffer?)

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1 Answer

  1. Editorial Team

    You’re using an ObjectOutputStream on write, but not on read.

    ObjectOutputStream is for serializing Serializable objects as well as primitives, so when you write a byte aray it includes type tagging information.

    You either need to change your client code to use ObjectInputStream, or just use a “plain” OutputStream when writing.

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