Bytecodes of loop VS iterator

/*
   *** CODE 1 ***
*/
public class Main {
  public Main();
    Code:
       0: aload_0
       1: invokespecial #8                  // Method java/lang/Object."<init>":
()V
       4: return

  public static void main(java.lang.String[]);
    Code:
      // Here is where we created "i" and allocated the List
(I)Ljava/lang/Integer;
      40: aastore
      41: astore_2
      42: aload_2
      43: dup
      44: astore        6
      46: arraylength
      47: istore        5
      49: iconst_0
      50: istore        4
      52: goto          71
      55: aload         6
      57: iload         4
      59: aaload
      60: astore_3
      61: iload_1
      62: aload_3
      63: invokevirtual #22                 // Method java/lang/Integer.intValue
:()I
      66: iadd
      67: istore_1
      68: iinc          4, 1
      71: iload         4
      73: iload         5
      75: if_icmplt     55
      78: getstatic     #26                 // Field java/lang/System.out:Ljava/
io/PrintStream;
      81: iload_1
      82: invokevirtual #32                 // Method java/io/PrintStream.printl
n:(I)V
      85: return
}




/*
   *** CODE 2 ***
*/
public class Main {

  public Main();
    Code:
       0: aload_0
       1: invokespecial #8                  // Method java/lang/Object."<init>":
()V
       4: return

  public static void main(java.lang.String[]);
    Code:
      // Here is where we created "i" and allocated the List
erator:()Ljava/util/Iterator;
      71: astore        4
      73: goto          94
      76: aload         4
      78: invokeinterface #35,  1           // InterfaceMethod java/util/Iterato
r.next:()Ljava/lang/Object;
      83: checkcast     #20                 // class java/lang/Integer
      86: astore_3
      87: iload_1
      88: aload_3
      89: invokevirtual #41                 // Method java/lang/Integer.intValue
:()I
      92: iadd
      93: istore_1
      94: aload         4
      96: invokeinterface #45,  1           // InterfaceMethod java/util/Iterato
r.hasNext:()Z
     101: ifne          76
     104: getstatic     #49                 // Field java/lang/System.out:Ljava/
io/PrintStream;
     107: iload_1
     108: invokevirtual #55                 // Method java/io/PrintStream.printl
n:(I)V
     111: return
}