package istlab.KisoJikken; import java.awt.Color; import java.awt.Component; import javax.swing.JTree; import javax.swing.tree.DefaultTreeCellRenderer; public class MyTreeCellRenderer extends DefaultTreeCellRenderer { @Override public Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean exp, boolean leaf, int row, boolean hasFocus) { super.getTreeCellRendererComponent(tree, value, sel, exp, leaf, row, hasFocus); // Assuming you have a tree of Strings String node = (String) ((MyFile) value).toString(); // If the node is a leaf and ends with "xxx" if (leaf && node.endsWith(".class")) { // Paint the node in blue setForeground(new Color(200, 200,230)); // setBackground(new Color(30, 30,50)); } return this; } }