SWT Java Tutorial

Sashes, also called splitters
Sashes can be horizontal or vertical;
The type is determined at construction time, and cannot be changed.
The default is vertical.
Passing SWT.HORIZONTAL or SWT.VERTICAL to the constructor determines the type:

Sash horizontalSash = new Sash(shell, SWT.HORIZONTAL); // Horizontal sash
Sash verticalSash = new Sash(shell, SWT.VERTICAL); // Vertical sash

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Sash;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
public class SashVerticalHori {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setText("Sash One");
    shell.setLayout(new FillLayout());
    new Text(shell, SWT.BORDER);
    new Sash(shell, SWT.HORIZONTAL);
    new Text(shell, SWT.BORDER);
    shell.pack();
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}