Thread: Java XML: IndexOutOfBoundsException When appending a node

Java XML: IndexOutOfBoundsException When appending a node

Dear all,

Now that I am writing a messenger program. The following code shall store the message history.
Sadly, I've encountered an "IndexOutOfBounds" exception on a line and I've been trying for a whole day,
but still can't figure out the problem.

So here it is.

	public static final SimpleDateFormat SDF = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	public static final String FILE_PATH = "/data/data/com.demo.xmppchat/";
	public static Map<Date, String> messagesMap = new TreeMap<Date, String>();
 
	// File should be saved as /username/buddy.xml
	public static void writeHistory(String username, String buddy, Map<Date, String> messages)
	{
		try {			
 
			// Check if the file exists. If the file does not exist, create and initiate one. 
			File file = new File(FILE_PATH + username);
			if (!file.exists()) {
				file.mkdirs();
			}	
			file = new File(FILE_PATH + username + "/" + buddy + ".xml");
			// file.setReadable(true); file.setWritable(true); file.setExecutable(true);
			if (!file.exists()) {
				file.createNewFile();				
				initiateHistoryFile(username, buddy);
			}
 
			// Now that the XML file should exists as we have created and initialized one.
 
			// TODO:
			// Now we modify the XML file
 
			DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
			DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
			Document doc = docBuilder.parse(file);
			Element root = doc.getDocumentElement();
			Element rootE = doc.getDocumentElement();	
			String s = "";
			Node n = null;
 
			for (Map.Entry<Date, String> entry : messages.entrySet()) {		
 
				// <message>
				Element messageE = doc.createElement("message");
				rootE.appendChild(messageE);
 
				// Set attribute to <message> element
				// messageE.setAttribute("id", "1");
 
				// <from>
				Element fromE = doc.createElement("from");
				fromE.appendChild(doc.createTextNode(buddy));
				messageE.appendChild(fromE);
 
				// <date>
				Element dateE = doc.createElement("date");
				s = SDF.format(entry.getKey());
				n = doc.createTextNode(s);
				dateE.appendChild(n);
				messageE.appendChild(dateE);
 
				// <text>
				Element textE = doc.createElement("text");
				s = entry.getValue();
				n = doc.createTextNode(s);
				textE.appendChild(n);
				messageE.appendChild(textE);	
 
				root.appendChild(messageE); // <- *** THIS IS WHERE "IndexOutOfBounds" exception OCCURS! ***
			}
 
			TransformerFactory transformerFactory = TransformerFactory.newInstance();
			Transformer transformer = transformerFactory.newTransformer();
			DOMSource source = new DOMSource(doc);
			StreamResult result = new StreamResult(file);
			transformer.transform(source, result);
 
			// Write the file
			// FileWriter fileWritter = new FileWriter(file.getName(),true);
	        // BufferedWriter bufferWritter = new BufferedWriter(fileWritter);
	        // bufferWritter.write("");
	        // bufferWritter.close();		
 
		} catch (Exception e) {
			ToneGenerator toneGenerator = new ToneGenerator(AudioManager.STREAM_SYSTEM, ToneGenerator.MAX_VOLUME);
			toneGenerator.startTone(ToneGenerator.TONE_PROP_BEEP);
			e.printStackTrace();
		}
	}

Thank you so much for your help.

--- Update ---

W/System.err(1067): java.lang.IndexOutOfBoundsException: Invalid index 1, size is 0
W/System.err(1067): at java.util.ArrayList.throwIndexOutOfBoundsException (ArrayList.java:251)
W/System.err(1067): at java.util.ArrayList.add(ArrayList.java:143)
W/System.err(1067): at org.apache.harmony.xml.dom.InnerNodeImpl.insertChi ldAt(InnerNodeImpl.java:126)
W/System.err(1067): at org.apache.harmony.xml.dom.InnerNodeImpl.appendChi ld(InnerNodeImpl.java:52)
W/System.err(1067): at com.demo.xmppchat.XMLReadWrite.writeHistory(XMLRea dWrite.java:113)

You are appending messageE to the root element twice, first to rootE and then later to root. both which point to the same document root. This might be where the exception is thrown.

Originally Posted by rolfba

You are appending messageE to the root element twice, first to rootE and then later to root. both which point to the same document root. This might be where the exception is thrown.

Thank you all, and yes, the problem is here. I have removed

rootE.appendChild(messageE);

and it works.

thats why i love java better than c++! it tells you when you go outside of your arrays

Originally Posted by derekxec

thats why i love java better than c++! it tells you when you go outside of your arrays

Yes! You're right. This program will probably crash if i'm writing it in C++