JList problema

Bom dia, estou programando um chat em java e nele estou com alguns problemas. primeiro problema segue na foto:
http://imgur.com/2eLZE7A
os nomes do JList não ficão em lista.
outro problema é quando clico no nome para mandar mensagem privada ele da o seguinte erro:

Exception in thread “AWT-EventQueue-0” java.lang.ClassCastException: com.mballem.app.frame.ImgsNText cannot be cast to java.lang.String

at com.mballem.app.frame.ClienteFrame.btnEnviarActionPerformed(ClienteFrame.java:370)

at com.mballem.app.frame.ClienteFrame.access$1000(ClienteFrame.java:23)

at com.mballem.app.frame.ClienteFrame$5.actionPerformed(ClienteFrame.java:262)

at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)

at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)

at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)

at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)

at java.awt.Component.processMouseEvent(Component.java:6533)

at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)

at java.awt.Component.processEvent(Component.java:6298)

at java.awt.Container.processEvent(Container.java:2236)

at java.awt.Component.dispatchEventImpl(Component.java:4889)

at java.awt.Container.dispatchEventImpl(Container.java:2294)

at java.awt.Component.dispatchEvent(Component.java:4711)

at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)

at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)

at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)

at java.awt.Container.dispatchEventImpl(Container.java:2280)

at java.awt.Window.dispatchEventImpl(Window.java:2746)

at java.awt.Component.dispatchEvent(Component.java:4711)

at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)

at java.awt.EventQueue.access$500(EventQueue.java:97)

at java.awt.EventQueue$3.run(EventQueue.java:709)

at java.awt.EventQueue$3.run(EventQueue.java:703)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)

at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)

at java.awt.EventQueue$4.run(EventQueue.java:731)

at java.awt.EventQueue$4.run(EventQueue.java:729)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)

at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)

at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Segue o codigo do JList:

private void refreshOnlines(ChatMessage message) {
    
    
    //  System.out.println(message.getSetOnlines().toString());
    
    Set<String> names = message.getSetOnlines();
    
    //names.remove(message.getName());
    
    
         
    String[] array = names.toArray(new String[names.size()]);
    
   dm.addElement(new ImgsNText(names + "", new ImageIcon("C:\\Users\\Matheus\\Desktop\\fb.png")));
    this.listOnlines.setCellRenderer(new Renderer());
    listOnlines.setModel(dm);
    this.listOnlines.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    //this.listOnlines.setListData(array);
    //this.listOnlines.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    this.listOnlines.setLayoutOrientation(JList.HORIZONTAL_WRAP);
   
      
}
    private void btnEnviarActionPerformed(java.awt.event.ActionEvent evt) {                                          
    String text = this.txtAreaSend.getText();
    String name = this.message.getName();
    
    this.message = new ChatMessage();
    
    if (this.listOnlines.getSelectedIndex() > -1) {
        this.message.setNameReserved((String) this.listOnlines.getSelectedValue());
        this.message.setAction(Action.SEND_ONE);
        this.listOnlines.clearSelection();
    } else {
        this.message.setAction(Action.SEND_ALL);
    }
    
    if (!text.isEmpty()) {
        this.message.setName(name);
        this.message.setText(text);

        this.txtAreaReceive.append("Você disse: " + text + "\n");
        
        this.service.send(this.message);
    } 
    
    this.txtAreaSend.setText("");
}