Org Eclipse Swt Widgets Java by API

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.ProgressBar;
import org.eclipse.swt.widgets.Shell;
public class MainClass {
  public static void main(String[] a) {
    Display display = new Display();
    Shell shell = new Shell(display);
    shell.setLayout(new GridLayout());
    // Create an indeterminate progress bar
    ProgressBar pb2 = new ProgressBar(shell, SWT.HORIZONTAL | SWT.INDETERMINATE);
    pb2.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
  }
}