提交 44dfbed4 编写于 作者: G github-actions

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上级 d3a6ba24
......@@ -11,203 +11,201 @@ import java.util.stream.StreamSupport;
* @param <E> the type that each index of the array will hold
*/
public class DynamicArray<E> implements Iterable<E> {
private static final int DEFAULT_CAPACITY = 16;
private int capacity;
private int size;
private Object[] elements;
/**
* constructor
*
* @param capacity the starting length of the desired array
*/
public DynamicArray(final int capacity) {
this.size = 0;
this.capacity = capacity;
this.elements = new Object[this.capacity];
}
/**
* No-args constructor
*/
public DynamicArray() {
this(DEFAULT_CAPACITY);
}
/**
* Adds an element to the array If full, creates a copy array twice the size of the current one
*
* @param element the element of type <E> to be added to the array
*/
public void add(final E element) {
if (this.size == this.elements.length) {
this.elements = Arrays.copyOf(this.elements, newCapacity(2 * this.capacity));
}
this.elements[this.size] = element;
size++;
}
/**
* Places element of type <E> at the desired index
*
* @param index the index for the element to be placed
* @param element the element to be inserted
*/
public void put(final int index, E element) {
this.elements[index] = element;
}
/**
* get method for element at a given index returns null if the index is empty
*
* @param index the desired index of the element
* @return <E> the element at the specified index
*/
public E get(final int index) {
return getElement(index);
}
/**
* Removes an element from the array
*
* @param index the index of the element to be removed
* @return <E> the element removed
*/
public E remove(final int index) {
final E oldElement = getElement(index);
fastRemove(this.elements, index);
if (this.capacity > DEFAULT_CAPACITY && size * 4 <= this.capacity)
this.elements = Arrays.copyOf(this.elements, newCapacity(this.capacity / 2));
return oldElement;
}
/**
* get method for size field
*
* @return int size
*/
public int getSize() {
return this.size;
}
/**
* isEmpty helper method
*
* @return boolean true if the array contains no elements, false otherwise
*/
public boolean isEmpty() {
return this.size == 0;
}
public Stream<E> stream() {
return StreamSupport.stream(spliterator(), false);
}
private void fastRemove(final Object[] elements, final int index) {
final int newSize = this.size - 1;
if (newSize > index) {
System.arraycopy(elements, index + 1, elements, index, newSize - index);
}
elements[this.size = newSize] = null;
}
private E getElement(final int index) {
return (E) this.elements[index];
}
private int newCapacity(int capacity) {
this.capacity = capacity;
return this.capacity;
}
/**
* returns a String representation of this object
*
* @return String a String representing the array
*/
@Override
public String toString() {
return Arrays.toString(Arrays.stream(this.elements).filter(Objects::nonNull).toArray());
}
/**
* Creates and returns a new Dynamic Array Iterator
*
* @return Iterator a Dynamic Array Iterator
*/
@Override
public Iterator iterator() {
return new DynamicArrayIterator();
}
private class DynamicArrayIterator implements Iterator<E> {
private int cursor;
@Override
public boolean hasNext() {
return this.cursor != size;
}
@Override
public E next() {
if (this.cursor > DynamicArray.this.size) throw new NoSuchElementException();
if (this.cursor > DynamicArray.this.elements.length)
throw new ConcurrentModificationException();
final E element = DynamicArray.this.getElement(this.cursor);
this.cursor++;
return element;
}
@Override
public void remove() {
if (this.cursor < 0) throw new IllegalStateException();
DynamicArray.this.remove(this.cursor);
this.cursor--;
}
@Override
public void forEachRemaining(Consumer<? super E> action) {
Objects.requireNonNull(action);
for (int i = 0; i < DynamicArray.this.size; i++) {
action.accept(DynamicArray.this.getElement(i));
}
}
}
/**
* This class is the driver for the DynamicArray<E> class it tests a variety of methods and prints
* the output
*/
public static void main(String[] args) {
DynamicArray<String> names = new DynamicArray<>();
names.add("Peubes");
names.add("Marley");
for (String name : names) {
System.out.println(name);
}
names.stream().forEach(System.out::println);
System.out.println(names);
System.out.println(names.getSize());
names.remove(0);
for (String name : names) {
System.out.println(name);
}
}
private static final int DEFAULT_CAPACITY = 16;
private int capacity;
private int size;
private Object[] elements;
/**
* constructor
*
* @param capacity the starting length of the desired array
*/
public DynamicArray(final int capacity) {
this.size = 0;
this.capacity = capacity;
this.elements = new Object[this.capacity];
}
/** No-args constructor */
public DynamicArray() {
this(DEFAULT_CAPACITY);
}
/**
* Adds an element to the array If full, creates a copy array twice the size of the current one
*
* @param element the element of type <E> to be added to the array
*/
public void add(final E element) {
if (this.size == this.elements.length) {
this.elements = Arrays.copyOf(this.elements, newCapacity(2 * this.capacity));
}
this.elements[this.size] = element;
size++;
}
/**
* Places element of type <E> at the desired index
*
* @param index the index for the element to be placed
* @param element the element to be inserted
*/
public void put(final int index, E element) {
this.elements[index] = element;
}
/**
* get method for element at a given index returns null if the index is empty
*
* @param index the desired index of the element
* @return <E> the element at the specified index
*/
public E get(final int index) {
return getElement(index);
}
/**
* Removes an element from the array
*
* @param index the index of the element to be removed
* @return <E> the element removed
*/
public E remove(final int index) {
final E oldElement = getElement(index);
fastRemove(this.elements, index);
if (this.capacity > DEFAULT_CAPACITY && size * 4 <= this.capacity)
this.elements = Arrays.copyOf(this.elements, newCapacity(this.capacity / 2));
return oldElement;
}
/**
* get method for size field
*
* @return int size
*/
public int getSize() {
return this.size;
}
/**
* isEmpty helper method
*
* @return boolean true if the array contains no elements, false otherwise
*/
public boolean isEmpty() {
return this.size == 0;
}
public Stream<E> stream() {
return StreamSupport.stream(spliterator(), false);
}
private void fastRemove(final Object[] elements, final int index) {
final int newSize = this.size - 1;
if (newSize > index) {
System.arraycopy(elements, index + 1, elements, index, newSize - index);
}
elements[this.size = newSize] = null;
}
private E getElement(final int index) {
return (E) this.elements[index];
}
private int newCapacity(int capacity) {
this.capacity = capacity;
return this.capacity;
}
/**
* returns a String representation of this object
*
* @return String a String representing the array
*/
@Override
public String toString() {
return Arrays.toString(Arrays.stream(this.elements).filter(Objects::nonNull).toArray());
}
/**
* Creates and returns a new Dynamic Array Iterator
*
* @return Iterator a Dynamic Array Iterator
*/
@Override
public Iterator iterator() {
return new DynamicArrayIterator();
}
private class DynamicArrayIterator implements Iterator<E> {
private int cursor;
@Override
public boolean hasNext() {
return this.cursor != size;
}
@Override
public E next() {
if (this.cursor > DynamicArray.this.size) throw new NoSuchElementException();
if (this.cursor > DynamicArray.this.elements.length)
throw new ConcurrentModificationException();
final E element = DynamicArray.this.getElement(this.cursor);
this.cursor++;
return element;
}
@Override
public void remove() {
if (this.cursor < 0) throw new IllegalStateException();
DynamicArray.this.remove(this.cursor);
this.cursor--;
}
@Override
public void forEachRemaining(Consumer<? super E> action) {
Objects.requireNonNull(action);
for (int i = 0; i < DynamicArray.this.size; i++) {
action.accept(DynamicArray.this.getElement(i));
}
}
}
/**
* This class is the driver for the DynamicArray<E> class it tests a variety of methods and prints
* the output
*/
public static void main(String[] args) {
DynamicArray<String> names = new DynamicArray<>();
names.add("Peubes");
names.add("Marley");
for (String name : names) {
System.out.println(name);
}
names.stream().forEach(System.out::println);
System.out.println(names);
System.out.println(names.getSize());
names.remove(0);
for (String name : names) {
System.out.println(name);
}
}
}
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