"[Fatal Error] :1:120: The processing instruction target matching "[xX][mM][lL]" is not allowed." [duplicate]

This question already has answers here: Error: The processing instruction target matching "[xX][mM][lL]" is not allowed (10 answers) Closed 6 years ago.

Here's a tough one for you.

I am working on a class project where I create a peer-to-peer chat program and I have this problem:

When I open up a chat window, no problems. When I open up a second window and try and login to the chat, I get this error:

**[Fatal Error] :1:120: The processing instruction target matching "[xX][mM][lL]" is not allowed.
org.xml.sax.SAXParseException: The processing instruction target matching "[xX][mM][lL]" is not allowed.
        at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:249)
        at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:284)
        at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:124)
        at chatter2.Chatter.process(Chatter.java:240)
        at chatter2.Chatter.run(Chatter.java:222)
        at java.lang.Thread.run(Thread.java:680)**

I am pretty sure it has something to do with how my code is creating the XML for participants.

Here is all the code I have written:

    /*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * NewJFrame.java
 *
 * Created on Nov 10, 2010, 2:11:39 PM
 */
package chatter2;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringBufferInputStream;
import java.io.StringReader;
import java.net.Socket;
import java.util.LinkedList;
import java.util.List;
import javax.swing.DefaultListModel;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.InputSource;

/**
 *
 * @author ericrea
 */
public class Chatter extends javax.swing.JFrame implements Runnable {

    PrintWriter out = null;
    BufferedReader in = null;
    boolean running = true;
    String partName = "";
    String chatHist = "";

    /** Creates new form NewJFrame */
    public Chatter() {
        initComponents();
        Server server = new Server();
        server.start();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        msgText = new javax.swing.JTextArea();
        send = new javax.swing.JButton();
        jPanel2 = new javax.swing.JPanel();
        chatText = new javax.swing.JTextArea();
        jPanel3 = new javax.swing.JPanel();
        userName = new javax.swing.JTextField();
        IPaddress = new javax.swing.JTextField();
        PortField = new javax.swing.JTextField();
        Login = new javax.swing.JButton();
        jButton1 = new javax.swing.JButton();
        jPanel4 = new javax.swing.JPanel();
        chatMembers = new javax.swing.JList();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setMinimumSize(new java.awt.Dimension(550, 550));

        jPanel1.setLayout(new java.awt.GridLayout(1, 0));

        msgText.setColumns(20);
        msgText.setRows(5);
        msgText.setPreferredSize(new java.awt.Dimension(240, 24));
        msgText.setRequestFocusEnabled(false);
        jPanel1.add(msgText);

        send.setText("Send");
        send.setPreferredSize(new java.awt.Dimension(100, 29));
        send.setRolloverEnabled(true);
        send.setSelected(true);
        send.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                sendActionPerformed(evt);
            }
        });
        jPanel1.add(send);

        getContentPane().add(jPanel1, java.awt.BorderLayout.PAGE_END);

        jPanel2.setLayout(new java.awt.GridLayout(1, 0));

        chatText.setBackground(new java.awt.Color(0, 255, 204));
        chatText.setColumns(20);
        chatText.setRows(5);
        jPanel2.add(chatText);

        getContentPane().add(jPanel2, java.awt.BorderLayout.LINE_END);

        jPanel3.setLayout(new java.awt.GridLayout(1, 0));

        userName.setText("UserName");
        jPanel3.add(userName);

        IPaddress.setText("127.0.0.1");
        IPaddress.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                IPaddressActionPerformed(evt);
            }
        });
        jPanel3.add(IPaddress);

        PortField.setText("44640");
        jPanel3.add(PortField);

        Login.setText("Login");
        Login.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                LoginActionPerformed(evt);
            }
        });
        jPanel3.add(Login);

        jButton1.setText("Logout");
        jPanel3.add(jButton1);

        getContentPane().add(jPanel3, java.awt.BorderLayout.PAGE_START);

        chatMembers.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        chatMembers.setModel(new javax.swing.AbstractListModel() {
            String[] strings = { "Item 1", "Item 2", "Item 3", "Item 4", "Item 5" };
            public int getSize() { return strings.length; }
            public Object getElementAt(int i) { return strings[i]; }
        });
        chatMembers.setPreferredSize(new java.awt.Dimension(80, 87));
        jPanel4.add(chatMembers);

        getContentPane().add(jPanel4, java.awt.BorderLayout.LINE_START);

        pack();
    }// </editor-fold>                        

    private void LoginActionPerformed(java.awt.event.ActionEvent evt) {                                      

        try {
            Socket s = new Socket(IPaddress.getText(), Integer.parseInt(PortField.getText()));
            out = new PrintWriter(s.getOutputStream());
            in = new BufferedReader(new InputStreamReader(s.getInputStream()));
            new Thread(this).start();
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = factory.newDocumentBuilder();
            Document doc = docBuilder.newDocument();
            Element root = doc.createElement("login");
            doc.appendChild(root);
            root.appendChild(doc.createTextNode(userName.getText()));

            TransformerFactory fact = TransformerFactory.newInstance();
            Transformer trans = fact.newTransformer();
            DOMSource source = new DOMSource(doc);
            StreamResult sResult = new StreamResult(out);
            trans.transform(source, sResult);
            out.println("\n");

            out.flush();
        } catch (Exception e) {
        }
    }                                     

    private void IPaddressActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
    }                                         

    private void sendActionPerformed(java.awt.event.ActionEvent evt) {                                     

    }                                    

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new Chatter().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JTextField IPaddress;
    private javax.swing.JButton Login;
    private javax.swing.JTextField PortField;
    private javax.swing.JList chatMembers;
    private javax.swing.JTextArea chatText;
    private javax.swing.JButton jButton1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JPanel jPanel4;
    private javax.swing.JTextArea msgText;
    private javax.swing.JButton send;
    private javax.swing.JTextField userName;
    // End of variables declaration                   

    public void run() {

        String buffer = "";
        while (running) {
            try {

                String line = in.readLine();
                System.out.println(line);

                if (line.equals("")) {

                    process(buffer);
                } else {

                    buffer = buffer + line;
                }
            } catch (Exception e) {
            }

        }
    }

    public void process(String buffer) {

        try {

            System.out.println("buffer in process is " + buffer);
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = factory.newDocumentBuilder();
            Document doc = docBuilder.parse(new StringBufferInputStream(buffer)); //new InputSource(new StringReader(buffer))
            Element root = doc.getDocumentElement();



            if (root.getNodeName().equals("message")) {
                chatHist = chatHist + root.getTextContent() + "\n";
                newMessage();

            }
            else if (root.getNodeName().equals("participants")) {
                DefaultListModel partNames = new DefaultListModel(); 
                for(int i = 0; i < root.getChildNodes().getLength(); i++){
                     //partName = partName + root.getChildNodes().item(i).getTextContent() + "/n";
                     partNames.addElement(root.getChildNodes().item(i).getTextContent());

                }
                chatMembers.setModel(partNames);

            }

        } catch (Exception e) {e.printStackTrace();
        }





    }

    public void cleanStop() {
    }

    public void newMessage() {
        chatText.setText(chatHist);
    }
}


    /*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package chatter2;


import java.io.*;
import java.net.*;
import java.util.LinkedList;
import java.util.List;
import org.w3c.dom.Document;


/**
 *
 * @author ericrea
 */
public class Server extends Thread {

    private ServerSocket ss = null;
    private List<Participant> parts = new LinkedList<Participant>();

    public Server(){
        try{
        ss = new ServerSocket(44640);
        }catch(Exception e){e.printStackTrace();
        }

    }

    @Override
    public void run() {

      //add this into a while loop
            while (true){
                 try{
            Socket s = ss.accept();
            Participant p = new Participant(this, s);
            p.start();
            getParts().add(p);
            }
            catch(Exception e){
            e.printStackTrace();}





//            System.out.println(" Got a client socket connection");
//            PrintWriter out =  new PrintWriter(s.getOutputStream());
//            BufferedReader in =  new BufferedReader(new InputStreamReader(s.getInputStream()));
//            out.println("hey there, want to chat");
//            out.flush();
//            String line = in.readLine();
//            System.out.println("Client said: " + line);


        }

    }
    public void message(Document doc){
        for (Participant p: getParts()){
            p.newMessage(doc);
        }
    }

    public void newParticipants(){
       int counter = 1;
        for(Participant p: getParts()){
            //System.out.println(counter + " time through the loop");
            counter++;
            p.newParticipant();
        }


    }

    public void cleanStop(){

    }
    public void logout(Participant p){
        parts.remove(p);
        newParticipants();
    }

    /**
     * @return the ss
     */
    public ServerSocket getSs() {
        return ss;
    }

    /**
     * @param ss the ss to set
     */
    public void setSs(ServerSocket ss) {
        this.ss = ss;
    }

    /**
     * @return the parts
     */
    public List<Participant> getParts() {
        return parts;
    }

    /**
     * @param parts the parts to set
     */
    public void setParts(List<Participant> parts) {
        this.parts = parts;
    }

}


    /*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package chatter2;

import java.io.*;
import java.util.*;
import java.net.*;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.InputSource;

/**
 *
 * @author ericrea
 */
public class Participant extends Thread {

    Server server = null;
    Socket client = null;
    PrintWriter out = null;
    BufferedReader in = null;
    boolean running = true;
    private String partName = null;

    public Participant(Server server, Socket client) throws IOException {
        this.client = client;
        this.server = server;
        out = new PrintWriter(client.getOutputStream());
        in = new BufferedReader(new InputStreamReader(client.getInputStream()));
    }

    //run and actONMessage will be in the chatter class as well
    @Override
    public void run() {


            String buffer = "";
            while (running) {
                try {
                    String line = in.readLine();

                    if (line.equals("")) {

                        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                        DocumentBuilder docBuilder = factory.newDocumentBuilder();
                        Document doc = docBuilder.parse(new InputSource(new StringReader(buffer)));
                        actOnMessage(doc);
                    } else {
                        buffer = buffer + line;
                    }

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

    }

    public void actOnMessage(Document doc) {

        Element root = doc.getDocumentElement();


        if (root.getNodeName().equals("login")) {
            setPartName(root.getTextContent());

            this.login();
        } else if (root.getNodeName().equals("message")) {
            message(doc);
        } else if (root.getNodeName().equals("logout")) {
            this.logout();
        }

    }

    public void message(Document doc) {
        server.message(doc);

    }

    public void login() {
        server.newParticipants();
    }

    public void logout() {
        server.logout(this);
    }

    public void newMessage(Document doc) {
        out.println(/*String version of the xml*/);
    }

    public void newParticipant() {
        try {

            List<Participant> partList = server.getParts();

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = factory.newDocu开发者_开发问答mentBuilder();
            Document doc = docBuilder.newDocument();
            Element root = doc.createElement("participants");
            doc.appendChild(root);

            for (Participant k : partList) {
                Element root1 = doc.createElement("participant");
                root.appendChild(root1);
                root1.appendChild(doc.createTextNode(k.getPartName()));

            }

            TransformerFactory fact = TransformerFactory.newInstance();
            Transformer trans = fact.newTransformer();
            DOMSource source = new DOMSource(doc);
            StreamResult sResult = new StreamResult(out);
            trans.transform(source, sResult);
            out.println("\n");

            out.flush();
        } catch (Exception e) {
        }
    }

    public void cleanStop() {
    }

    public void getParticipantName() {
    }

    /**
     * @return the partName
     */
    public String getPartName() {
        return partName;
    }

    /**
     * @param partName the partName to set
     */
    public void setPartName(String partName) {
        this.partName = partName;
    }
}

---

The problem is that you have more than one XML header or noise before one.

The typical start of an XML doc...

<?xml version='1.0'?>

looks like a PI, but isn't. If you have an extra, or if you have anything other than a BOM before one, that's the error you'll get.

---

I faced similar issue on deploying a spring webapp on weblogic. We had first line as blank in xml file. This caused XML parsing failure with this error. After removing this, it worked!! Hope it is useful info for others too.. :)

---

There is unwanted content may be space of other noisy thing before the starting of you xml namely :

<?xml version='1.0'?>

Make sure there is nothing before the starting of your xml . This will solve the problem , One related example is :

related reference

---

I encountered the same problem and I solved like following.

Following code cause error.

<?xml version="1.0" encoding="UTF-8"?>

So, I simply put a space before ?>.

<?xml version="1.0" encoding="UTF-8" ?>

After I did like that, there was no more error.

---

Another answer to this is using XML within XML will break you need to not parse the inner XML and use the CDATA tag see here:

http://www.w3schools.com/xml/xml_cdata.asp

ie:

<?xml version='1.0'?>
  <sometag>
  <![CDATA[
    <?xml version='1.0'?>
    <nonParsedTag></nonParsedTag>
  ]]></sometag>

---

I figured it out. I needed to clear the buffer after every new participant is created. duh!!!

thanks for the help!!

---

I recently was working on a Spring MVC startup project sample where I used maven built tool. When I run my server using jetty I got this processing instruction error and I found that my web.xml was having an extra tag before the <xml> tag and it started with the <DOCTYPE> tag instead.

So I removed the below tag which was the start tag,

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" >

and had the below tag,

<?xml version="1.0" encoding="UTF-8"?>

as the start tag of my web.xml and it solved my issue.

Note: Please ensure there is no comments, tags, free spaces or any unwanted characters left before the <?xml ...?> tag. This will mainly throw these type of error while parsing the xml files.

---

It is actually because of unwanted content, in my case it was because I always use comments for understanding the code later so I had comments with <!-- --> before the <?xml version='1.0'?>

So just put comments after this line and Problem Solved!