Java：在从本地JList向JList添加项时遇到困难

Question

我在这里遇到了一个问题，我创建了一个actionListener，它旨在创建一个随机的人，并将其添加到JList中以显示在JScrollPane上。到目前为止，一切都很顺利，只是每当我单击JButton添加一个新的人员时，JList不会添加到当前列表中，而是每次都会替换它，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actionevent行中看到它。不管怎样，谢谢你的帮助我的朋友们！

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////////////////////



}

}       

    {

       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

您正在您的ActionListener中创建一个新的JListnewbiex，它永远不会添加到JFrame中。相反，重用原始的JListnewbie并将新的human添加到其模型中。使用DefaultListModel这是可变的。

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

您将需要一个自定义单元格呈现器来显示JList中的human对象。请参见编写自定义单元格呈现器

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;
   }
}