Generics and the ArrayList Class - Java - page 737

Answers to Self-Test Exercises
1. list.add("Hello");
2. instruction .set(5, "Go");
3. instruction .add(5, "Go");
4. No. The index for set must be greater than or equal to 0 and less than the size of
the ArrayList . Thus, you can replace any existing element, but you cannot place
the element at any higher index. This situation is unlike that of an array. If an
array is partially filled to index 10 , you can add an element at index 20 , as long as
the array is that large. With an ArrayList , you cannot add an element beyond
the last-used index.
5. No. The index for add must be greater than or equal to 0 and less than or equal
to the size of the ArrayList . Thus, you can replace any existing element or add
an element to the end of the list, but you cannot place the element at any higher
index. This situation is unlike that of an array. If an array is partially filled to
index 10 , you can add an element at index 20 , as long as the array is that large.
With an ArrayList , you cannot add an element beyond one more than the last-
used index.
6. The index for add (that is, index2 ) is allowed to be one larger than the index for
set (that is, index1 ). The index for set must be strictly less than the size of the
ArrayList . The index for add can also be equal to the size of the ArrayList .
7. Yes. The ArrayList can contain more than 20 elements. The number 20 used as
an argument to the constructor merely gives the initial memory allocation for the
ArrayList . More memory is automatically allocated when it is needed.
8. for (Double element : numberList )
System.out.println(element);

9. import java.util.ArrayList;
/**
Class for sorting an ArrayList of Strings lexicographically
(approximately alphabetically).
*/
public class StringSelectionSort
{

/**
Sorts the ArrayList a so that a.get(0), a.get(1),...,
a.get(a.size()

− 1) are in lexicographic order.

*/
public static void sort(ArrayList<String> a)
{
int index, indexOfNextSmallest;
for (index = 0; index < a.size()

−

1; index++)
{ //Place the correct value in position index: