Summary that Pulls All the Concepts TOGETHER (Ref.  13)

The following code pulls all the concepts discussed
in the lat 5 references together so that you can have an
accurate picture of what is happening. Study this
carefully.

...the code involver a main application and a student class
...the java.util package is imported thereby giving you
   access to the collection framework
...an ArrayList object is created and a reference is stored in an interface variable called list
...a lot of things happened behind the scenes when we created this object . Refer to
   Reference 11 above and  you will see where the ArrayList  class exists in the 
   hierarchy of the collection framework. Remember the  rules on inheritance and you will
   understand that the following happened  when the object was created:
        ...interface Collection {...} 
        ...interface List extends Collection {...} 
        ...abstract class AbstractCollection implements Collection {...}
        ...abstract class AbstractList extends AbstractCollection implements List {...} 
        ...class ArrayList extends AbstractList {...}
...a reference to this ArrayList is stored in a List interface variable called list
...I declared and ititialized a String array and an int array (each holding 10 values)
...a for loop new is used to create 10 separate Student objects 
        ...the constructor for the Student class receives an arbitrary ID (passed as the for loop
           value +1)
        ...the getName and getAge methods are called in the loop to pass a name and age to
           each Student object
        ...Important-- the last statement in the loop uses the add method on the list variable to place
           a reference to the specific Student object, just created, in the ArrayList. Notice how list
           is referred to (which is an interface variable of type List) .  This is very IMPORTANT 
           because it shows how methods available to the interface type can be applied and the 
           parameter can be any object (in this case a reference to a stu object).
        ...Because we are now playing with an interface type variable, many more possibilities are available
           that are more general in scope and more powerful and useful to programmers.
...the next for loop works backwards and does the following:
        ...uses the get method on the list variable and stores the reference in a variable called s of type Object
        ...uses the toString method on that object and because this method was also defined in the 
           Student class  then the original toString method (which was bound to the object) was the one
           that was applied to the s object. (Refer to Reference 10)
        ...the next command merely prints the data   id, name, age
...The above loop demonstrates casting, method binding, inheritance, and polymorphism in 3 statements.
...A bland line is printed
...An Iterator variable called iter is created. Iterator is a multipurpose interface that provided methods
    for traversing some data structure. It is applied to the List reference variable called list.
...A while loop is then executed as long as there are values to be printed. Remember the hasNext method
   of the Iterator interface is applied on the iter reference variable, which held a reference to the list reference
   variable,  which in turn held a reference to the ArrayList, which was the concrete structure that held references
   to the 10 Student objects.
...The toString method in the Student class allowed the data to be printed
...The final line hold the output on the screen

package untitled163;
import java.util.*;
import javax.swing.*;
public class Application1
{
public static void main(String args[])
{
List list = new ArrayList();
String[] names={"Mary","Paul","Susan","Maria","Cody","William","Travis","Ellen","Robert","Troy"};
int[] ages={22,21,34,45,32,20,19,28,29,17};
for(int a=0;a<=9;a++)
{
Student stu = new Student(a+1);
stu.getName(names[a]);
stu.getAge(ages[a]);
list.add(stu);
}
for (int i = 9; i >= 0; i--)
{
Object s=list.get(i);
String g=s.toString();
System.out.println(g);
}
System.out.println(" ");
Iterator iter = list.iterator();
while (iter.hasNext())
System.out.println(iter.next());
JOptionPane.showMessageDialog(null,"lll");
}
}
//**********************************************************

package untitled163;
public class Student
{
private int id;
private String name;
private int age; 
public Student(int x)
{
id=x;
}
public void getName(String n)
{
name=n;
}
public void getAge(int y)
{
age=y;
}
public String toString()
{
String s=id+" "+name+" "+age;
return s;
}
}