@Singleton
public class MyViewPart {

private TableViewer viewer;

@PostConstruct
public void createControls(Composite parent)
  viewer = new TableViewer(parent, SWT.MULTI | SWT.H_SCROLL
		        | SWT.V_SCROLL | SWT.FULL_SELECTION | SWT.BORDER);
 { // my code here }
public void loadData(filename)()
 {
  // my code here
 }
 	
}

public class LoadDataHandler {

@Execute
public void execute() {
	    
		
	    Shell shell = new Shell(Display.getDefault());
	    DirectoryDialog dialog = new DirectoryDialog(shell);
	    String fileSelected = dialog.open();
	   
	    MyViewPart data = new MyViewPart();
	    data.loadData(fileSelected); 
  }

}