Я создаю 4 потока, и каждый поток связан с пользовательским интерфейсом. Пользовательский интерфейс выполняет долгосрочную задачу, для этого я использовал SwingWorker. Но проблема в том, что вместо того, чтобы работать как многопоточное приложение, оно работает в очереди.

Интересно отметить, что когда я удаляю SwingWorker, он ведет себя и работает как многопоточный.

Мой код как:

NewClass

package thread;

public class NewClass
{
    public static void main(String[] args) throws Exception
    {
        for(int i=0; i<4 ; i++)
        {
            new ThreadFront().startsThread();
            Thread.sleep(2000);
        } 
    }
}

class ThreadFront implements Runnable
{
    private Thread t;

    public ThreadFront() 
    {
        t = new Thread(this, "");

    }

    public void startsThread()
    {
        t.start();
    }

    @Override
    public void run()
    {
        try
        {
            UI ui = new UI();
            ui.startThread();
        }
        catch(Exception ae)
        {
            ae.printStackTrace();
        }
    }
}

UI класс

package thread;

import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.SwingWorker;

public class UI extends javax.swing.JFrame
{
    public UI()
    {
        initComponents();    
        setVisible(true); 
    }

    public void startThread() throws Exception
    {       
        new SwingWorker<Integer, Integer>()
        {
            @Override
            pro,tected Integer doInBackground() throws Exception 
            {                
                for(int i=0; i<10;i++)
                {
                    jTextArea1.append(""+i);
                    Thread.sleep(3000);
                }
                return 0;
            }

            @Override
            protected void process(List<Integer> chunks) 
            {
                for(Integer message : chunks)
                {
                    jProgressBar1.setValue(message); 
                    jProgressBar1.repaint();
                }
            }

            @Override
            protected void done() 
            {
                try 
                {
                    get();
                }
                catch(final Exception ex) 
                {
                    ex.printStackTrace();
                }
            }
        }.execute();
    }

    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jPanel2 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        jPanel3 = new javax.swing.JPanel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jLabel2 = new javax.swing.JLabel();
        jobid_field = new javax.swing.JLabel();
        jProgressBar1 = new javax.swing.JProgressBar();
        work_field = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        session_field = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
        setLocationByPlatform(true);
        setResizable(false);
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowClosing(java.awt.event.WindowEvent evt) {
                formWindowClosing(evt);
            }
        });

        jPanel1.setLayout(new java.awt.BorderLayout());

        jPanel2.setBackground(new java.awt.Color(204, 204, 204));
        jPanel2.setBorder(javax.swing.BorderFactory.createMatteBorder(1, 1, 1, 1, new java.awt.Color(255, 255, 255)));
        jPanel2.setForeground(new java.awt.Color(204, 204, 204));

        jLabel1.setFont(new java.awt.Font("Century Gothic", 1, 14)); // NOI18N
        jLabel1.setText("iZoneX Math Process");

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addGap(18, 18, 18)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 304, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(86, Short.MAX_VALUE))
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );

        jPanel1.add(jPanel2, java.awt.BorderLayout.NORTH);

        jPanel3.setBackground(new java.awt.Color(204, 204, 204));
        jPanel3.setBorder(javax.swing.BorderFactory.createMatteBorder(1, 1, 1, 1, new java.awt.Color(255, 255, 255)));

        jTextArea1.setEditable(false);
        jTextArea1.setBackground(new java.awt.Color(255, 255, 204));
        jTextArea1.setColumns(20);
        jTextArea1.setFont(new java.awt.Font("Century Gothic", 1, 12)); // NOI18N
        jTextArea1.setForeground(new java.awt.Color(255, 0, 0));
        jTextArea1.setLineWrap(true);
        jTextArea1.setRows(5);
        jTextArea1.setWrapStyleWord(true);
        jScrollPane1.setViewportView(jTextArea1);

        jLabel2.setText("Job ID. :");

        jLabel4.setText("Processing: ");

        jLabel3.setText("Session ID: ");

        javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
        jPanel3.setLayout(jPanel3Layout);
        jPanel3Layout.setHorizontalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                        .addComponent(jLabel2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jobid_field, javax.swing.GroupLayout.PREFERRED_SIZE, 115, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(33, 33, 33)
                        .addComponent(jLabel3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(session_field, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                    .addComponent(jProgressBar1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addGroup(jPanel3Layout.createSequentialGroup()
                        .addComponent(jLabel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(work_field, javax.swing.GroupLayout.PREFERRED_SIZE, 320, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap())
        );
        jPanel3Layout.setVerticalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel3Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                    .addComponent(jLabel2, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jobid_field, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jLabel3)
                    .addComponent(session_field, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 148, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jProgressBar1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(work_field, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 18, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap())
        );

        jPanel1.add(jPanel3, java.awt.BorderLayout.CENTER);

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

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

    private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   

    }                                  

    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JProgressBar jProgressBar1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JLabel jobid_field;
    private javax.swing.JLabel session_field;
    private javax.swing.JLabel work_field;
    // End of variables declaration                   

}

Какая в этом случае альтернатива рабочим потокам в Swing?