title: Why does importing JFrame require inheritance but FlowLayout, JLabel, etc not?
body: <p>I just started learning about GUIs and was watching a tutorial from "thenewboston" where he wrote this. But I don't understand why JFrame is the only import that's inherited? I'm not sure if this is just one of those cases where it has be because java would give it an error otherwise.</p>
  
  <pre><code>import java.awt.FlowLayout;
  import javax.swing.JFrame;
  import javax.swing.JLabel;
  
  public class tuna extends JFrame {
  
      private JLabel item1;
  
      public tuna(){
          super("The title bar");
          setLayout(new FlowLayout());            
          item1 = new JLabel("This is a sentence.");
          item1.setToolTipText("This is gonna show up on hover");
          add(item1);
      }
  }
  </code></pre>