Java by API/javax.swing/JSeparator

new JSeparator()

 
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JSeparator;
public class MainClass {
  public static void main(String args[]) {
    JFrame f = new JFrame("JSeparator Sample");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setLayout(new GridLayout(0, 1));
    JLabel above = new JLabel("Above Separator");
    f.add(above);
    JSeparator separator = new JSeparator();
    f.add(separator);
    JLabel below = new JLabel("Below Separator");
    f.add(below);
    f.setSize(300, 100);
    f.setVisible(true);
  }
}

new JSeparator(int orientation)

 
import javax.swing.JFrame;
import javax.swing.JSeparator;
public class Main {
  public static void main(String[] a){
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.add(new JSeparator(JSeparator.VERTICAL));
    frame.setSize(300, 200);
    frame.setVisible(true);
  }

}