import org.eclipse.swt.events.ModifyEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.widgets.Text;

public class TestClass implements ModifyListener {
	private Text textField;
	
	public TestClass() {
		// init fields
		textField.setText("foobar");
		
		textField.addModifyListener(this);
	}
	
	public void update() {
		textField.removeModifyListener(this);
		
// toggle visibilty of elements or change data
		if (textField.getText().equals("someString")) {
			textField.setText("bla");
		}
		
		textField.addModifyListener(this);
	}
	
	@Override
	public void modifyText(ModifyEvent e) {
		if (e.getSource() == textField) {
			//
		}
		
		// update all fields etc.
		update();
	}
	
}