Refresh JProgressBar trough Observer Observable

Question

I have a problem with my JProgressBar. I have a frame with a progressbar and i want to repaint after a part of the log is read. I want to change the value and the string painted in the progressbar. I have never used a progressbar before so i am quite new to this things. Method below is in a class called Reader it is not in the frame Class.

    public void readLog(File file){     
    ArrayList<String> list = getFile(file);     
    setChanged();
    notifyObservers("Start reading log...");        
    readPlayers(list);
    setChanged();
    notifyObservers("Reading headshots...")     
    readHeadshots(list);
    setChanged();   
    notifyObservers("Reading headshots...")
    setChanged();
    notifyObservers("Done reading log...")
}

This is the progressbar in the frame. This (Main)Frame gets called(is written) when the application starts.

    progressBar = new JProgressBar(0,3);
    progressBar.setValue(0);
    progressBar.setStringPainted(true)

This is the update that gets called when notifyObservers is used.

public void update(Observable o, Object arg) {  ;           
    progressBar.setValue((progressBar.getValue() + 1));     
    progressBar.setStringPainted(true);
    progressBar.setString((String)arg);
    progressBar.repaint();      
}

I thought it would work but it doesn't. I have checked if it gets into the update method and it does. The arg (the string that is given with the notifyobservers) works aswell when i put it in a system.out.prtln.

Can someone help me? Or point me in the good direction?

UPDATE

OK here is how it works. I click on Read Log on the frame i posted below. I have a controller for that button that looks like this

if(jb.getText() == "Read Log")  {       
        File selectedFile = FileSelector.getInstance().selectFile();            
        Reader.getInstance().readLog(selectedFile);     
    }

I use JFileChooser to choose a file.

public File selectFile(){
    JFileChooser chooser= new  JFileChooser();
    int returnVal = chooser.showOpenDialog(null);
    if(returnVal == JFileChooser.APPROVE_OPTION) {
        File selectedFile = chooser.getSelectedFile();              
        return selectedFile;
    }
    return null;
}

When i have selected a server log that i want to read i click on open on the JFileChooser and it will send the file to my method readLog on my Class Reader.

The readLog method:

    public void readLog(File file){     
    this.file = file;
    execute(); // if i remove this execute it wont start reading the log.
}

Here is my frame.

package view;

import java.awt.Color;

public class MainFrame extends JFrame { 
private TableModelPlayer model; 
private JTable playerTable;
private JTextField txtSearchTerm;
JProgressBar progressBar;

public MainFrame() {
    initGui();
}

private void initGui(){
    setResizable(false);
    setAutoRequestFocus(true);
    setTitle("WARBAND STATISTICS");
    setDefaultCloseOperation(EXIT_ON_CLOSE);    
    this.setPreferredSize(new Dimension(1000,900)); 

    JPanel tablePanel = new JPanel();

    JPanel buttonPanel = new JPanel();

    progressBar = new JProgressBar(0,100);
    progressBar.setVisible(true);       
    progressBar.setStringPainted(true);

    SwingWorker myWorker = new Reader();
            myWorker.execute(); // if i have this here it doesn't startedreading thelog    
    myWorker.addPropertyChangeListener(new PropertyChangeListener() {
      @Override
      public void propertyChange(final PropertyChangeEvent event) {
        switch (event.getPropertyName()) {
        case "progress":
          progressBar.setIndeterminate(false);
          progressBar.setValue((Integer) event.getNewValue());
          break;
        case "message":
            progressBar.setString((String)event.getNewValue());
          break;
        }
     }
    });
    GroupLayout groupLayout = new GroupLayout(getContentPane());
    groupLayout.setHorizontalGroup(
            groupLayout.createParallelGroup(Alignment.LEADING)
            .addGroup(groupLayout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
                            .addGroup(groupLayout.createSequentialGroup()
                                    .addComponent(tablePanel, GroupLayout.PREFERRED_SIZE, 748, GroupLayout.PREFERRED_SIZE)
                                    .addGap(18))
                                    .addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
                                            .addGap(10)
                                            .addComponent(progressBar, GroupLayout.PREFERRED_SIZE, 724, GroupLayout.PREFERRED_SIZE)
                                            .addGap(32)))
                                            .addComponent(buttonPanel, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                            .addContainerGap())
            );
    groupLayout.setVerticalGroup(
            groupLayout.createParallelGroup(Alignment.LEADING)
            .addGroup(groupLayout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
                            .addGroup(groupLayout.createSequentialGroup()
                                    .addComponent(tablePanel, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(progressBar, GroupLayout.PREFERRED_SIZE, 25, GroupLayout.PREFERRED_SIZE))
                                    .addComponent(buttonPanel, GroupLayout.DEFAULT_SIZE, 849, Short.MAX_VALUE))
                                    .addContainerGap())
            );



    JScrollPane scrollPane = new JScrollPane();
    tablePanel.add(scrollPane);

    JButton btnReadLog = new JButton("Read Log");
    btnReadLog.setBackground(Color.YELLOW);
    btnReadLog.addActionListener(new MainFrameController(btnReadLog));
    btnReadLog.setPreferredSize(new Dimension(200,40));
    btnReadLog.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
        }
    });

    JButton btnSelectPlayer = new JButton("Select player");
    btnSelectPlayer.setBackground(Color.YELLOW);
    btnSelectPlayer.setPreferredSize(new Dimension(200, 40));
    btnSelectPlayer.addActionListener(new MainFrameController(btnSelectPlayer, this));

    txtSearchTerm = new JTextField();
    txtSearchTerm.setColumns(10);

    JRadioButton radioBtnId = new JRadioButton("Search by id");     
    JRadioButton radioBtnName = new JRadioButton("Search by name");
    radioBtnName.setSelected(true);
    ButtonGroup group = new ButtonGroup();
    group.add(radioBtnId);
    group.add(radioBtnName);    

    JButton btnSearch = new JButton("Search");
    btnSearch.setBackground(Color.YELLOW);
    btnSearch.addActionListener(new MainFrameController(btnSearch, radioBtnId, radioBtnName, txtSearchTerm));

    JButton btnReset = new JButton("Reset List");
    btnReset.setBackground(Color.YELLOW);
    btnReset.addActionListener(new MainFrameController(btnReset));



    GroupLayout gl_buttonPanel = new GroupLayout(buttonPanel);
    gl_buttonPanel.setHorizontalGroup(
            gl_buttonPanel.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_buttonPanel.createSequentialGroup()
                    .addGroup(gl_buttonPanel.createParallelGroup(Alignment.LEADING)
                            .addGroup(gl_buttonPanel.createSequentialGroup()
                                    .addComponent(btnSearch)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(btnReset, GroupLayout.PREFERRED_SIZE, 104, GroupLayout.PREFERRED_SIZE))
                                    .addComponent(btnReadLog, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addComponent(btnSelectPlayer, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addComponent(txtSearchTerm, GroupLayout.DEFAULT_SIZE, 206, Short.MAX_VALUE)
                                    .addComponent(radioBtnId)
                                    .addComponent(radioBtnName))
                                    .addContainerGap())
            );
    gl_buttonPanel.setVerticalGroup(
            gl_buttonPanel.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_buttonPanel.createSequentialGroup()
                    .addGap(37)
                    .addComponent(btnReadLog, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                    .addGap(5)
                    .addComponent(btnSelectPlayer, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addComponent(txtSearchTerm, GroupLayout.PREFERRED_SIZE, 29, GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(ComponentPlacement.UNRELATED)
                    .addComponent(radioBtnId)
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addComponent(radioBtnName)
                    .addPreferredGap(ComponentPlacement.UNRELATED)
                    .addGroup(gl_buttonPanel.createParallelGroup(Alignment.BASELINE)
                            .addComponent(btnSearch)
                            .addComponent(btnReset))
                            .addContainerGap(609, Short.MAX_VALUE))
            );
    buttonPanel.setLayout(gl_buttonPanel);

    playerTable = new JTable(model = new TableModelPlayer()){
        @Override
        public boolean isCellEditable(int row, int column){
            return false;
        }
    };
    playerTable.addMouseListener(new MouseListenerTablePlayer(playerTable));
    playerTable.getTableHeader().setReorderingAllowed(false);
    playerTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

    scrollPane.setViewportView(playerTable);    
    scrollPane.setPreferredSize(new Dimension(720,800));
    getContentPane().setLayout(groupLayout);



    setVisible(true);
    this.pack();
    this.setLocationRelativeTo(null);
}

public JTable getPlayerTable() {
    return playerTable;
}



public void setPlayerTable(JTable playerTable) {
    this.playerTable = playerTable;

}

}

My reader class:

package model;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.swing.SwingWorker;

import DataLayer.DatabaseConnector;

public class Reader extends SwingWorker <Void, String>{

private static Reader instance;
File file;

public Reader(){

}

public static Reader getInstance(){             
    if(instance == null){
        instance = new Reader();
    }       
    return instance;
}

public ArrayList<String> getFile(File file){            
    try (BufferedReader br = new BufferedReader(new FileReader(file.getAbsolutePath())))
    {
        String sCurrentLine;
        ArrayList<String> list = new ArrayList<String>();
        while ((sCurrentLine = br.readLine()) != null) {                
            list.add(sCurrentLine);                     
        }           
        return list;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null; 
}

public void readLog(File file){     
    this.file = file;
    execute();
}

public void readPlayers(ArrayList<String> list){    
    System.out.println("Reading players...");
    ArrayList<String> joinedPlayers = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("has joined the game with ID: ")) {             
            joinedPlayers.add(string);                  
        }
    }
    Player p;
    for (String string : joinedPlayers){
        String strList[] = string.split(" ");           
        p = new Player();
        p.playerId = strList[10];
        p.playerName = strList[3];              
        if(PlayerContainer.getInstance().checkIfPlayerExists(p) == false){
            PlayerContainer.getInstance().getPlayersList().add(p);          
            DatabaseConnector.getInstance().insertPlayer(p);                            
        }
    }   
}

public void readHeadshots(ArrayList<String> list){
    System.out.println("Reading headshots...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> headshotList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_headshot>")) {                
            headshotList.add(string);                   
        }
    }       
    for (String string : headshotList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.headshots = p.headshots + 1;  
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readOneHanderSwordKills(ArrayList<String> list){
    System.out.println("Reading one handed sword kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> oneHandSwordKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_swordone>")) {                
            oneHandSwordKillsList.add(string);                  
        }
    }       
    for (String string : oneHandSwordKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.oneHandSwordKills = p.oneHandSwordKills + 1;              
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readTwoHanderSwordKills(ArrayList<String> list){
    System.out.println("Reading two handed sword kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> twoHandSwordKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_swordtwo>")) {                
            twoHandSwordKillsList.add(string);                  
        }
    }       
    for (String string : twoHandSwordKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.twoHandSwordKills = p.twoHandSwordKills + 1;                      
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readOneHanderAxeKills(ArrayList<String> list){
    System.out.println("Reading one handed axe kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> oneHandAxeKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_axeone>")) {              
            oneHandAxeKillsList.add(string);                    
        }
    }       
    for (String string : oneHandAxeKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.oneHandAxeKills = p.oneHandAxeKills + 1;                  
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readTwoHanderAxeKills(ArrayList<String> list){
    System.out.println("Reading two handed axe kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> twoHandAxeKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_axetwo>")) {              
            twoHandAxeKillsList.add(string);                    
        }
    }       
    for (String string : twoHandAxeKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.twoHandAxeKills = p.twoHandAxeKills + 1;              
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readJavelinKills(ArrayList<String> list){
    System.out.println("Reading javelin kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> javelinKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_javelin>")) {             
            javelinKillsList.add(string);                   
        }
    }       
    for (String string : javelinKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.javelinKills = p.javelinKills + 1;                
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readMaulKills(ArrayList<String> list){
    System.out.println("Reading maul kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> maulKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_maul>")) {                
            maulKillsList.add(string);                  
        }
    }       
    for (String string : maulKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.maulKills = p.maulKills + 1;                  
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readCrossbowKills(ArrayList<String> list){
    System.out.println("Reading crossbow kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> crossbowKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_crossbow>")) {                
            crossbowKillsList.add(string);                  
        }
    }       
    for (String string : crossbowKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.crossbowKills = p.crossbowKills + 1;              
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readBowKills(ArrayList<String> list){
    System.out.println("Reading bow kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> bowKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_bow>")) {             
            bowKillsList.add(string);                   
        }
    }       
    for (String string : bowKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.bowKills = p.bowKills + 1;                    
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readCouchedLanceKills(ArrayList<String> list){
    System.out.println("Reading couched lance kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> couchedLanceKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_couchedlance>")) {                
            couchedLanceKillsList.add(string);                  
        }
    }       
    for (String string : couchedLanceKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.couchedLanceKills = p.couchedLanceKills + 1;                  
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readSpearKills(ArrayList<String> list){
    System.out.println("Reading spear kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> spearKillsList = new ArrayList<String>();
    for (String string : list) {            
        if (string.contains("<img=ico_spear>")) {               
            spearKillsList.add(string);                 
        }
    }       
    for (String string : spearKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.spearKills = p.spearKills + 1;                    
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readDeaths (ArrayList<String> list){
    System.out.println("Reading deaths...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> deathList = new ArrayList<String>();      
    for (String string : list) {                
        if (string.contains("<img=ico")) {              
            deathList.add(string);                  
        }
    }           
    for (String string : deathList) {
        String strList[] = string.split(" ");
        String playername = "";
        if(strList.length == 6){
            playername = strList[5];
        }           
        if(strList.length == 5){
            playername = strList[4];
        }

        for (Player p : PlayerContainer.getInstance().getPlayersList()) {               
            if(p.getPlayerName().equalsIgnoreCase(playername)){                 
                p.deaths = p.deaths + 1;                    
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}

public void readBluntKills (ArrayList<String> list){
    System.out.println("Reading blunt kills...");
    ArrayList<Player> DbList = new ArrayList<Player>();
    ArrayList<String> bluntKillsList = new ArrayList<String>();     
    for (String string : list) {                
        if (string.contains("<img=ico_blunt>")) {               
            bluntKillsList.add(string);                 
        }
    }           
    for (String string : bluntKillsList) {
        String strList[] = string.split(" ");                       
        for (Player p : PlayerContainer.getInstance().getPlayersList()) {
            if(p.getPlayerName().equalsIgnoreCase(strList[3])){
                p.bluntKills = p.bluntKills + 1;                    
                DbList.add(p);
            }
        }           
    }
    DatabaseConnector.getInstance().updatePlayer(DbList);
}


@Override
protected Void doInBackground() throws Exception {
    ArrayList<String> list = getFile(file);         

    String message=null; 
    message="Start reading log...";
    publish(message);
    readPlayers(list);
    setProgress(0);     

    message="Start reading headshots...";
    publish(message);       
    readHeadshots(list);
    setProgress(7); 

    message="Start reading one handed sword kills...";
    publish(message);
    readOneHanderSwordKills(list);
    setProgress(14);

    message="Start reading two handed sword kills...";
    publish(message);
    readTwoHanderSwordKills(list);
    setProgress(21); 

    message="Start reading one handed axe kills...";
    publish(message);
    readOneHanderAxeKills(list);
    setProgress(28); 

    message="Start reading two handed axe kills...";
    publish(message);
    readTwoHanderAxeKills(list);
    setProgress(35);

    message="Start reading javelin kills...";
    publish(message);
    readJavelinKills(list);
    setProgress(42);

    message="Start reading maul kills...";
    publish(message);
    readMaulKills(list);
    setProgress(49);

    message="Start reading crossbow kills...";
    publish(message);
    readCrossbowKills(list);
    setProgress(56);

    message="Start reading bow kills...";
    publish(message);
    readBowKills(list);
    setProgress(63); 


    message="Start reading couched lance kills...";
    publish(message);
    readCouchedLanceKills(list);
    setProgress(70); 

    message="Start reading spear kills...";
    publish(message);
    readSpearKills(list);
    setProgress(77);  

    message="Start reading blunt kills...";
    publish(message);
    readBluntKills(list);
    setProgress(84);        

    message="Start reading deaths...";
    publish(message);
    setProgress(91);
    readDeaths(list);   

    PlayerContainer.getInstance().updatePlayerList();

    message="Done reading log...";
    publish(message);
    setProgress(100);  

    return null;

}

@Override
protected void process(List<String> chunks){
     if(chunks == null || chunks.isEmpty())
         return;
    firePropertyChange("message",null,chunks.get(0));
}

}

Answer 1

If i were you i'd use PropertyChangeListener (Oberserver) and PropertyChangeSupport (Observable). And to don't block your gui if your readLog(File f) it's a heavy operation. I'd use SwingWorker. Here is a complete example with progressBar that i really like SwingWorker example.

A simple example:

public class Worker extends SwingWorker<Void, String> {



    @Override
    protected Void doInBackground() throws Exception {
       //here you make heavy task this is running in another thread not in EDT
       setProgress(0);
       setChanged();
       publish("Start reading log...");   
       setProgress(43);
       //another operation
       publish("Start reading log...");    
       setProgress(89);
       .
       .
       return null; // you have to add this, Void is wrapper class of native void
    }
    @Override
    protected void process(List<String> chunks){
      // here is called when you call publish in doInBackground, this is executed in EDT 
        if(chunks == null || chunks.isEmpty())
                return;
        firePropertyChange("message",null,chunks.get(0));
    }

}

And in your client code where you have the progressBar:

SwingWorker myWorker = new Worker();
myWorker.addPropertyChangeListener(new PropertyChangeListener() {
  @Override
  public void propertyChange(final PropertyChangeEvent event) {
    switch (event.getPropertyName()) {
    case "progress":
      myProgressBar.setIndeterminate(false);
      myProgressBar.setValue((Integer) event.getNewValue());
      break;
    case "message":
      myProgressBar.setString((String)event.getNewValue());
      break;
    }
 }
});
myWorker.execute(); // you use swing worker in this way, you can only execute it once!

UPDATE

Don't make your SwingWorker a singleton, you only can execute each instance one time and besides your "singleton" is not a singleton cause your constructor is public.

You have to init your worker something like this

    public class MainFrame extends JFrame {


    private JProgressBar progressBar;
    private PropertyChangeListener listener = new MyPropertyChangeListener();

   //in some place you have something like    
    readLogButton.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent evt){
               if(jb.getText().equals("Read Log"))  { // you compare objects with equals not with ==       
                File selectedFile = FileSelector.getInstance().selectFile();            
                Reader myWorker = new Reader();
                myWorker.addPropertyChangeListener(listener);
                myWorker.readLog(selectedFile);     
              }
            }
     });

     //And the private inner class (you can use anonymous class if you want it)
       private class MyPropertyChangeListener implements PropertyChangeListener{
                         @Override
                         public void propertyChange(final PropertyChangeEvent event) {
                            switch (event.getPropertyName()) {
                               case "progress":
                                    progressBar.setIndeterminate(false);
                                    progressBar.setValue((Integer) event.getNewValue());
                                    break;
                               case "message":
                                    progressBar.setString((String)event.getNewValue());
                                    break;
                            }
                        }
      }


    }