SWT Java Tutorial

Set the alignment of the text/image label of a button in the constructor of the Button class, or you can use the setAlignment method after it has been created:

public void setAlignment(int alignment)
To query a button for its label alignment, call the getAlignment method:

public int getAlignment()

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class ButtonAlignment {
  public static void main(String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display, SWT.SHELL_TRIM);
    shell.setLayout(new FillLayout());
    Button button = new Button(shell, SWT.RIGHT);
    button.setText("text on the button");
    button.setAlignment(SWT.CENTER);
    
    shell.open();
    // Set up the event loop.
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        // If no more entries in event queue
        display.sleep();
      }
    }
    display.dispose();
  }
}