title: JComboBox in Java, Error in declaration
body: <p>I got the next simple program in Java, I got it online, because im trying to learn Java, but dont know  how to fix it:</p>
  
  <pre><code>import javax.swing.*;
          import java.awt.*;
          import java.awt.event.*;
  
          public class java2 extends JPanel {
  
              public java2 () {
                  setLayout(new Gridlayout(2,1));
                  JList lista = new JList(java2.ids);
                  add(new JScrollpane(lista));
                  JComboBox combo=new JComboBox();
                  for (int i=0;i&lt;100 ;i++ ) {
                      combo.addItem(Integer.toString(i));
                      add(combo);
                  }
              }
          public static void main(String args[]) {
              java1 lista=new Java1();
              JFrame ventana=new JFrame();
              ventana.getContentPane().add(lista,BorderLayout.CENTER);
              ventana.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent evt){System.exit(0);}});
              ventana.setSize(200,200);
              ventana.setVisible(true);
          }
          }
  </code></pre>
  
  <p>Im getting the next problems every time i compile, as i say, im new to java and can say that i know how to fix em:</p>
  
  <pre><code>java2.java:8: error: cannot find symbol
          setLayout(new Gridlayout(2,1));
                        ^
    symbol:   class Gridlayout
    location: class java2
  java2.java:9: error: cannot find symbol
          JList lista = new JList(java2.ids);
                                       ^
    symbol:   variable ids
    location: class java2
  java2.java:10: error: cannot find symbol
          add(new JScrollpane(lista));
                  ^
    symbol:   class JScrollpane
    location: class java2
  java2.java:18: error: cannot find symbol
      java1 lista=new Java1();
      ^
    symbol:   class java1
    location: class java2
  java2.java:18: error: cannot find symbol
      java1 lista=new Java1();
                      ^
    symbol:   class Java1
    location: class java2
  Note: java2.java uses unchecked or unsafe operations.
  Note: Recompile with -Xlint:unchecked for details.
  5 errors
  </code></pre>