Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

get(size() −1)
addFirst(e)
add(0,e)
addLast(e)
add(size(),e)
removeFirst()
remove(0)
removeLast()
remove(size() − 1)
6.1.3 A Simple Array-Based Implementation
An obvious choice for implementing the array list ADT is to use an array A, where
A[i] stores (a reference to) the element with index i. We choose the size N of array
A sufficiently large, and we maintain the number of elements in an instance
variable, n < N.
The details of this implementation of the array list ADT are simple. To implement
the get(i) operation, for example, we just return A[i]. Implementations of
methods add(i, e) and remove(i) are given in Code Fragment 6.1. An
important (and time-consuming) part of this implementation involves the shifting of
elements up or down to keep the occupied cells in the array contiguous. These
shifting operations are required to maintain our rule of always storing an element
whose list index is i at index i in the array A. (See Figure 6.1 and also Exercise R-
6.12.)
Code Fragment 6.1: Methods add(i, e) and
remove(i) in the array implementation of the array
list ADT. We denote, with n, the instance variable
storing the number of elements in the array list.
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