SWT Java Tutorial

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class GridLayoutHORIZONTALALIGNCENTER {
  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new Shell(display);
    GridLayout layout = new GridLayout();
    layout.numColumns = 3;
    layout.makeColumnsEqualWidth = true;
    shell.setLayout(layout);
    // Create the big button in the upper left
    GridData data = new GridData(GridData.FILL_BOTH);
    data.widthHint = 200;
    Button one = new Button(shell, SWT.PUSH);
    one.setText("one");
    one.setLayoutData(data);
    // Create a composite to hold the three buttons in the upper right
    Composite composite = new Composite(shell, SWT.NONE);
    
    // Create button "three"
    data = new GridData(GridData.HORIZONTAL_ALIGN_CENTER);
    Button three = new Button(composite, SWT.PUSH);
    three.setText("three");
    three.setLayoutData(data);
    shell.pack();
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}