import javax.swing.*;

class test01{
    public static void main(String args[]){
        JFrame frame   = new JFrame("画面テスト");
        frame.setBounds(200, 200, 500, 100);          //int x, int y, int width, int height
        JPanel panel   = new JPanel();
        JButton button = new JButton("TEST-BOTTON");
        panel.add(button);
        frame.add(panel);
        frame.setVisible(true);
    }
}