小编Fal*_*lso的帖子

我有一个程序可以检测某些机器何时在线并创建一个带有绿色"在线"图标的按钮来显示这一点.我想添加功能以定期检查此机器是否仍在线,如果不是,请将图标更改为我已定义的"离线"图标.

我有一个简单的TreeCellRenderer,它从节点中提取JButton,并将其输出到JTree.

public class ButtonCellRenderer extends JButton implements TreeCellRenderer {

  @Override
  public Component getTreeCellRendererComponent(JTree tree, Object value, boolean     selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
    //setBackgroundNonSelectionColor(tree.getBackground());
    ProgressButton b = null;
    if ((value != null) && (value instanceof DefaultMutableTreeNode)) {
      Object userObject = ((DefaultMutableTreeNode) value).getUserObject();
      if (userObject instanceof ProgressButton) {
        b = (ProgressButton) userObject;
        return b;
      }
    }
    if (b == null) {
      System.out.println("Null!");
      DefaultTreeCellRenderer defaultRenderer = new DefaultTreeCellRenderer();
      return defaultRenderer.getTreeCellRendererComponent(tree,
              value, selected, expanded, leaf, row, hasFocus);
    } else …