Java by API/javax.swing.tree/TreeCellRenderer

implements TreeCellRenderer

import java.awt.BorderLayout;
import java.awt.ruponent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.ToolTipManager;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeCellRenderer;
public class MainClass {
  public static void main(final String args[]) {
    JFrame frame = new JFrame("Tree Tips");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTree tree = new JTree(new String[]{"a","b","c"});
    ToolTipManager.sharedInstance().registerComponent(tree);
    TreeCellRenderer renderer = new ToolTipTreeCellRenderer();
    tree.setCellRenderer(renderer);
    JScrollPane scrollPane = new JScrollPane(tree);
    frame.add(scrollPane, BorderLayout.CENTER);
    frame.setSize(300, 150);
    frame.setVisible(true);
  }
}
class ToolTipTreeCellRenderer implements TreeCellRenderer {
  DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();
  public ToolTipTreeCellRenderer() {
  }
  public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected,
      boolean expanded, boolean leaf, int row, boolean hasFocus) {
    Object tip = null;
    if (value != null) {
      
      if (value instanceof DefaultMutableTreeNode) {
        tip = ((DefaultMutableTreeNode) value).getUserObject();
      } else {
        tip = tree.convertValueToText(value, selected, expanded, leaf, row, hasFocus);
      }
      renderer.setToolTipText((String)tip);
    }
    renderer.setText((String)tip);
    return renderer;
  }
}