CS $251$

Program $05$

Main topics: Arrays

ArrayLists

Program Specification:

An array that can grow and shrink $($as needed$)$ at run time is generally called a dynamic array. You are to write a class named DynArray which can hold double values that adheres to the following:

The physical size of the array at all times is a nonnegative power of two $($smallest of which is $1).$

The physical size is never more than $2$ times the number of elements which occupy it $($with exception to when it is at size $1).$

Mandatory Instance variables:

private double$[]$ array;

private int size;

private int nextIndex;

Mandatory Instance methods:

public DynArray$()//$ constructor

$//$ set array to a nes array of double, of size one

$//$ set size to one,

$\frac{\frac{?}{?}}{?}$ and set nextIndex to zero.

public int arraysize$()//$ accessor

$//$ return the value of size.

public int elements$()//$ accessor

$//$ return the value of nextIndex.

public double at $($int index$)//$ accessor

$\frac{\frac{?}{?}}{?}$ if $0$ index $$ nextIndex

$//$ return the value of array$[$index$].$

$//$ else

$//$ return Double.NaN.

private void grow$()$

$//$ make array a reference to an array that is twice as large

$//$ and contains the same values for indicies $0$ through

$//$ nextIndex $-1,$ and adjust size appropriately.

private void shrink$()$

$//$ make array a reference to an array that is half as large

$\frac{\frac{?}{?}}{?}$ and contains the same values for indicies $0$ through