SomeTest.java

import javax.swing.*;
import java.awt.*;

/**
 * Created by kirill on 06.03.17.
 */
public class SomeTest implements Runnable {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new SomeTest());
    }

    public void run() {
        JFrame frame = new JFrame("Test frame");
        frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);

        JPanel panel = new JPanel();
        panel.setPreferredSize(new Dimension(800, 600));
        frame.add(panel, BorderLayout.CENTER);

        frame.pack();
        frame.setVisible(true);
    }
}