import javax.swing.JFrame;
import javax.swing.JTree;
public class Main {
public static void main(String[] args) throws Exception {
JFrame f = new JFrame("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTree tree = new JTree();
tree.putClientProperty("JTree.lineStyle", "Angled");
// tree.putClientProperty("JTree.lineStyle", "Horizontal");
// tree.putClientProperty("JTree.lineStyle", "None");
for (int i = 0; i < tree.getRowCount(); i++) {
tree.expandRow(i);
}
f.add(tree);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}