Java:从本地 JList 添加项目到 JList 时遇到问题

Question

我在这里遇到了一个问题，我创建了一个actionListener，它的目的是创建一个随机的人类并将其添加到JList以显示在JScrollPane上。到目前为止，一切都很顺利，除了每当我单击 JButton 添加新人员时，JList 不会添加到当前列表，而是每次都会再次替换它，因此 Jlist 上只显示一个项目。我知道问题发生在哪里，您将立即在操作事件行中看到它。不管怎样，感谢 friend 们的帮助!

private static final JTextArea PlayerList = new JTextArea(30, 100);
private JList newbie;
private List<Human> members = new ArrayList<Human>();
private JTextArea Area;
private String[] listString;
private String[] newString;
private ArrayList<String> list = new ArrayList<String>();
private ArrayList<String> zz = new ArrayList<String>();


public JTabbedPaneFrame() throws FileNotFoundException 
{
    super("JTabbedPane Demo");


    JTabbedPane tabbedPane = new JTabbedPane(); 

    JPanel Gladiator = new JPanel();
    getContentPane().add(Gladiator); 

    /////////////Tabbed Pane Gladiator///////////////////

    tabbedPane.addTab("Gladiator", null, Gladiator, "");




    Box ListOfPlayers = Box.createVerticalBox();
    ListOfPlayers.add(Box.createRigidArea(new Dimension(100,100)));
    ListOfPlayers.setBorder(new TitledBorder("List of Players"));

    Area = new JTextArea(20, 15);
    Area.setLineWrap(true);
    Area.setWrapStyleWord(false);

    final JList newbie = new JList();

    JScrollPane PlayerViewer = new JScrollPane(newbie);
    PlayerViewer.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    ListOfPlayers.add(PlayerViewer);


    Gladiator.add(ListOfPlayers);
    /////////////Vertical Box between Text and Tabbed Profile//////

    Box Randomer = Box.createVerticalBox();
    Randomer.setBorder(new TitledBorder("Randomize or Add Gladiator"));
    JButton AddIndividual = new JButton("Add a Player");
    Randomer.add(AddIndividual); 

    Gladiator.add(Randomer);



    AddIndividual.addActionListener(new ActionListener()
    {

        public void actionPerformed(ActionEvent event)
        {


                String x = "";
                String y = "";
                String z = "";
                String ee = "";
                ArrayList<String> listx = new ArrayList<String>();
                ArrayList<String> zzx = new ArrayList<String>();
                JList newbiex;
                Human temp;
                try {


                    temp = new Human();
                    x = temp.toString();
                    y = temp.getSurname();
                    z = temp.getFirstName();
                    listx.add(x);
                    ee = String.format(y + ", " + z );
                    zzx.add(ee);
                    listString = new String[zzx.size()];
                    listString = zzx.toArray(listString);

                    newbiex = new JList(zzx.toArray());
                    newbie.setModel(newbiex.getModel());

                    members.add(temp);


                    for(String W: listString) /////testing diff method here////
                    {
                          Area.append(W);
                    }

                    } 
                catch (FileNotFoundException e) 
                    {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                    }




        }


    });





    add(tabbedPane); 



    /////////////Action Buttons////////////////////



}

}       

HumanRenderer 类扩展了 DefaultListCellRenderer

    {

       public Component getListCellRendererComponent(JList list, Object value,
          int index, boolean isSelected, boolean cellHasFocus) {

          JLabel label = new JLabel(); 
          if (value != null) {
             Human human = (Human) value;
             label.setText(human.getSurname() + ", " + human.getFirstName());
          }

          return label;
       }
    }

Answer 1

您正在 ActionListener 中创建一个新的 JList newbiex，但您从未将其添加到 JFrame 中。相反，重新使用原始的 JList newbie 并将新的 Human 添加到其模型中。使用可变的 DefaultListModel。

DefaultListModel<Human> model = new DefaultListModel<>();
JList<Human> newbie = new JList<>(model);

您将需要一个自定义单元格渲染器来显示 JList 中的 Human 对象。请参阅Writing a Custom Cell Renderer

<小时/>

class HumanRenderer extends DefaultListRenderer {
   @Override
   public Component getListCellRendererComponent(JList list, Object value,
      int index, boolean isSelected, boolean cellHasFocus) {

      JLabel label = new JLabel(); 
      if (value != null) {
         Human human = (Human) value;
         label.setText(human.getSurName() + ", " + human.getFirstName());
      }

      return label;
   }
}