Java Swing客户ListCellRenderer

Question

我正在尝试制作一个自定义的JList，它显示一个任务列表，其中每个任务表示如下-类型:由3个不同的图标表示，状态由2个图标表示，名称为简单的字符串。

我的问题是，一开始，自定义CellRenderer不会为列表中的项目使用适当的图标，直到我突出显示该项目。现在我稍微修改了一下，它总是使用相同的图标(task_small.png)，我确信我传入的数据是正确的。

此外，如果您有关于如何以其他方式改进此代码的建议/批评，我将很乐意听取。我不确定使用JPanel是否是正确的选择。

//imports...

class TaskListCellRenderer extends JPanel implements ListCellRenderer {
    private ClassLoader cl = this.getClass().getClassLoader();
    private JLabel statusAndName = new JLabel();
    private JLabel icon;

      public TaskListCellRenderer() {
        setOpaque(true);
        setLayout(new BorderLayout());
        setBorder(new EmptyBorder(5,5,5,5));
      }

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

        if (entry.isStatus())
            statusAndName.setIcon(new ImageIcon(cl.getResource("finished.png")));
        else
            statusAndName.setIcon(new ImageIcon(cl.getResource("unfinished.png")));
        statusAndName.setText(entry.getName());

        statusAndName.setBorder(new EmptyBorder(0,15,0,0));
        int type = entry.getType();
        System.out.println(type);
        if (type == 1)
            icon =  new JLabel(new ImageIcon(cl.getResource("task_small.png")));
        else if (type == 2)
            icon = new JLabel(new ImageIcon(cl.getResource("issue_small.png")));
        else if (type == 3)
            icon  = new JLabel(new ImageIcon(cl.getResource("request_small.png")));


        //My attempts to make this work- at first I had 3 pre-made Icons which I made icon = to;
        remove(statusAndName);
        remove(icon);
        add(icon, BorderLayout.WEST);
        add(statusAndName, BorderLayout.CENTER);
        revalidate();
        repaint();
        if (isSelected) {
          setBackground(Constants.blue);
          setForeground(Constants.black);
        } else {
          setBackground(Constants.lightGrey);
          setForeground(Constants.black);
        }
        return this;
      }
    }

Answer 1

这解决了我的问题，而且可能效率更高。谢谢大家！

class TaskListCellRenderer extends JPanel implements ListCellRenderer {
    private ClassLoader cl = this.getClass().getClassLoader();
    private JLabel statusAndName = new JLabel();
    private JLabel icon = new JLabel();
    private Icon finishedIcon = new ImageIcon(cl.getResource("finished.png"));
    private Icon unfinishedIcon = new ImageIcon(cl.getResource("unfinished.png"));
    private Icon taskIcon = new ImageIcon(cl.getResource("task_small.png"));
    private Icon requestIcon = new ImageIcon(cl.getResource("request_small.png"));
    private Icon issueIcon = new ImageIcon(cl.getResource("issue_small.png"));

      public TaskListCellRenderer() {
        setOpaque(true);
        setLayout(new BorderLayout());
        setBorder(new EmptyBorder(5,5,5,5));
        add(icon, BorderLayout.WEST);
        add(statusAndName, BorderLayout.CENTER);
      }

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

        if (entry.isStatus())
            statusAndName.setIcon(finishedIcon);
        else
            statusAndName.setIcon(unfinishedIcon);

        statusAndName.setText(entry.getName());
        statusAndName.setBorder(new EmptyBorder(0,15,0,0));

        int type = entry.getType();
        System.out.println(type);
        if (type == 1)
            icon.setIcon(taskIcon); 
        else if (type == 2)
            icon.setIcon(issueIcon); 
        else if (type == 3)
            icon.setIcon(requestIcon); 

        if (isSelected) {
          setBackground(Constants.blue);
          setForeground(Constants.black);
        } else {
          setBackground(Constants.lightGrey);
          setForeground(Constants.black);
        }
        return this;
      }
    }