title: ImageIcon doesn't appear on JLabel or JButton
body: <p>I want to put <code>Image</code> on <code>JButton</code> or <code>JLabel</code>, but It doesn't appear on the program.</p>
  <pre><code>import javax.swing.*;
  
  public class JButtonEx extends JFrame{
  
  JButtonEx() {
      setSize(300,300);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      JLabel label = new JLabel(new ImageIcon(&quot;network/star.png&quot;));
      add(label);
      setVisible(true);
  }
  
  public static void main(String[] args) {
      new JButtonEx();
  }
  }
  </code></pre>