// Class ArrayList<E> can be used to store a list of values of type E.
import java.util.*;
public class ArrayList<E> {
private E[] elementData; // list of values
private int size; // current number of elements in the list
public static final int DEFAULT_CAPACITY = 100;
// post: constructs an empty list of default capacity
this(DEFAULT_CAPACITY);
}
// pre : capacity >= 0 (throws IllegalArgumentException if not)
// post: constructs an empty list with the given capacity
@SuppressWarnings("unchecked")
if (capacity < 0) {
}
elementData
= (E
[]) new Object[capacity
]; size = 0;
}
// post: returns the current number of elements in the list
public int size() {
return size;
}
// pre : 0 <= index < size() (throws IndexOutOfBoundsException if not)
// post: returns the value at the given index in the list
public E get(int index) {
checkIndex(index);
return elementData[index];
}
// post: creates a comma-separated, bracketed version of the list
if (size == 0) {
return "[]";
} else {
String result
= "[" + elementData
[0]; for (int i = 1; i < size; i++) {
result += ", " + elementData[i];
}
result += "]";
return result;
}
}
// post : returns the position of the first occurrence of the given
// value (-1 if not found)
public int indexOf(E value) {
for (int i = 0; i < size; i++) {
if (elementData[i].equals(value)) {
return i;
}
}
return -1;
}
// post: returns true if list is empty, false otherwise
public boolean isEmpty() {
return size == 0;
}
// post: returns true if the given value is contained in the list,
// false otherwise
public boolean contains(E value) {
return indexOf(value) >= 0;
}
// post: appends the given value to the end of the list
public void add(E value) {
ensureCapacity(size + 1);
elementData[size] = value;
size++;
}
// pre : 0 <= index <= size() (throws IndexOutOfBoundsException if not)
// post: inserts the given value at the given index, shifting subsequent
// values right
public void add(int index, E value) {
if (index < 0 || index > size) {
}
ensureCapacity(size + 1);
for (int i = size; i >= index + 1; i--) {
elementData[i] = elementData[i - 1];
}
elementData[index] = value;
size++;
}
// pre : 0 <= index < size() (throws IndexOutOfBoundsException if not)
// post: removes value at the given index, shifting subsequent values left
public void remove(int index) {
checkIndex(index);
for (int i = index; i < size - 1; i++) {
elementData[i] = elementData[i + 1];
}
elementData[size - 1] = null;
size--;
}
// pre : 0 <= index < size() (throws IndexOutOfBoundsException if not)
// post: replaces the value at the given index with the given value
public void set(int index, E value) {
checkIndex(index);
elementData[index] = value;
}
// post: list is empty
public void clear() {
for (int i = 0; i < size; i++) {
elementData[i] = null;
}
size = 0;
}
// post: appends all values in the given list to the end of this list
public void addAll(ArrayList<E> other) {
ensureCapacity(size + other.size);
for (int i = 0; i < other.size; i++) {
add(other.elementData[i]);
}
}
// post: returns an iterator for this list
public Iterator<E> iterator() {
return new ArrayListIterator();
}
// post: ensures that the underlying array has the given capacity; if not,
// the size is doubled (or more if given capacity is even larger)
public void ensureCapacity(int capacity) {
if (capacity > elementData.length) {
int newCapacity = elementData.length * 2 + 1;
if (capacity > newCapacity) {
newCapacity = capacity;
}
elementData
= Arrays.
copyOf(elementData, newCapacity
); }
}
// post: throws an IndexOutOfBoundsException if the given index is
// not a legal index of the current list
private void checkIndex(int index) {
if (index < 0 || index >= size) {
}
}
private class ArrayListIterator implements Iterator<E> {
private int position; // current position within the list
private boolean removeOK; // whether it's okay to remove now
// post: constructs an iterator for the given list
public ArrayListIterator() {
position = 0;
removeOK = false;
}
// post: returns true if there are more elements left, false otherwise
public boolean hasNext() {
return position < size();
}
// pre : hasNext() (throws NoSuchElementException if not)
// post: returns the next element in the iteration
public E next() {
if (!hasNext()) {
}
E result = elementData[position];
position++;
removeOK = true;
return result;
}
// pre : next() has been called without a call on remove (throws
// IllegalStateException if not)
// post: removes the last element returned by the iterator
public void remove() {
if (!removeOK) {
}
position--;
removeOK = false;
}
}
}