import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Monitor;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class SWTHelloWorld {

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Hallo Welt");
        shell.setLayout(new FillLayout(SWT.VERTICAL));

        Text text = new Text(shell, SWT.NONE);
        text.setText("Welt");
        Label label = new Label(shell, SWT.NONE);
        label.setText("Hallo " + text.getText());
        Button button = new Button(shell, SWT.PUSH);
        button.setText("Klick");
        button.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                label.setText("Hallo " + text.getText());
            }
        });
        shell.setSize(150, 150);
        Monitor mon = display.getPrimaryMonitor();
        Rectangle mRect = mon.getBounds();
        int x = (mRect.width - 150) / 2;
        int y = (mRect.height - 150) / 2;
        shell.setLocation(x, y);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}