title: .java uses unchecked and unsafe operation
body: <p>here is my java code:</p>
  
  <pre><code>import javax.swing.*;
  
  public class Employee1 extends JFrame {
  
      JPanel panel;
      JLabel l1;
      JList list;
  
      public Employee1() {
          super("Employee Details");
          panel = new JPanel();
          l1 = new JLabel("City : ");
          String cities[] = {"Mumbai", "Delhi", "Madras"};
          list = new JList(cities);
          panel.add(l1);
          panel.add(list);
          getContentPane().add(panel);
          setSize(400, 400);
          setVisible(true);
      }
  
      public static void main(String args[]) {
          Employee1 obj = new Employee1();
      }
  }
  </code></pre>
  
  <p><strong>this code gives me warning .java uses unchecked and unsafe operation. i have exams so please help me to go through it</strong>. </p>