Java
Создаем новое Java консольное приложение ... и напишем код
package org.example;
import java.util.ArrayList;
public class Program {
public static void main(String[] args)
{
ArrayList<String> myList1 = new ArrayList<String>();
// добавляем элемент в конец
myList1.add("Car");
// myList1 = ["Car"]
// добавляем элемент в конец
myList1.add("House");
// myList1 = ["Car", "House"]
// добавляем элемент в конец
myList1.add("Notebook");
// myList1 = ["Car", "House", "Notebook"]
// посмотреть элемент по индексу
String elem = myList1.get(1);
// elem = "House"
// myList1 = ["Car", "House", "Notebook"]
// вставить элемент по индексу 1
myList1.add(1, "Airplane");
// myList1 = ["Car", "Airplane", "House", "Notebook"]
// удалить элемент по индексу
myList1.remove(1);
// myList1 = ["Car", "House", "Notebook"]
}
}
Kotlin
Создаем новое Kotlin консольное приложение ... и напишем код
import java.util.ArrayList;
fun main() {
val myList1 = ArrayList<String>()
// добавляем элемент в конец
myList1.add("Car")
// myList1 = ["Car"]
// добавляем элемент в конец
myList1.add("House")
// myList1 = ["Car", "House"]
// добавляем элемент в конец
myList1.add("Notebook")
// myList1 = ["Car", "House", "Notebook"]
// посмотреть элемент по индексу
val elem = myList1[1]
// elem = "House"
// myList1 = ["Car", "House", "Notebook"]
// вставить элемент по индексу 1
myList1.add(1, "Airplane")
// myList1 = ["Car", "Airplane", "House", "Notebook"]
// удалить элемент по индексу
myList1.removeAt(1)
// myList1 = ["Car", "House", "Notebook"]
}
Java
class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable
{
private static final int DEFAULT_CAPACITY = 10;
transient Object[] elementData; // non-private to simplify nested class access
private int size;
public ArrayList(int initialCapacity) {
if (initialCapacity > 0) {
this.elementData = new Object[initialCapacity];
} else if (initialCapacity == 0) {
this.elementData = EMPTY_ELEMENTDATA;
} else {
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
}
}
public ArrayList() {
this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
}
public ArrayList(Collection<? extends E> c) {
Object[] a = c.toArray();
if ((size = a.length) != 0) {
if (c.getClass() == ArrayList.class) {
elementData = a;
} else {
elementData = Arrays.copyOf(a, size, Object[].class);
}
} else {
// replace with empty array.
elementData = EMPTY_ELEMENTDATA;
}
}
public void trimToSize() {
modCount++;
if (size < elementData.length) {
elementData = (size == 0)
? EMPTY_ELEMENTDATA
: Arrays.copyOf(elementData, size);
}
}
public void ensureCapacity(int minCapacity) {
if (minCapacity > elementData.length
&& !(elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
&& minCapacity <= DEFAULT_CAPACITY)) {
modCount++;
grow(minCapacity);
}
}
private Object[] grow(int minCapacity) {
int oldCapacity = elementData.length;
if (oldCapacity > 0 || elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
int newCapacity = ArraysSupport.newLength(oldCapacity,
minCapacity - oldCapacity, /* minimum growth */
oldCapacity >> 1 /* preferred growth */);
return elementData = Arrays.copyOf(elementData, newCapacity);
} else {
return elementData = new Object[Math.max(DEFAULT_CAPACITY, minCapacity)];
}
}
private Object[] grow() {
return grow(size + 1);
}
public int size() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public boolean contains(Object o) {
return indexOf(o) >= 0;
}
public int indexOf(Object o) {
return indexOfRange(o, 0, size);
}
int indexOfRange(Object o, int start, int end) {
Object[] es = elementData;
if (o == null) {
for (int i = start; i < end; i++) {
if (es[i] == null) {
return i;
}
}
} else {
for (int i = start; i < end; i++) {
if (o.equals(es[i])) {
return i;
}
}
}
return -1;
}
public int lastIndexOf(Object o) {
return lastIndexOfRange(o, 0, size);
}
int lastIndexOfRange(Object o, int start, int end) {
Object[] es = elementData;
if (o == null) {
for (int i = end - 1; i >= start; i--) {
if (es[i] == null) {
return i;
}
}
} else {
for (int i = end - 1; i >= start; i--) {
if (o.equals(es[i])) {
return i;
}
}
}
return -1;
}
public Object clone() {
try {
ArrayList<?> v = (ArrayList<?>) super.clone();
v.elementData = Arrays.copyOf(elementData, size);
v.modCount = 0;
return v;
} catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError(e);
}
}
public Object[] toArray() {
return Arrays.copyOf(elementData, size);
}
@SuppressWarnings("unchecked")
public <T> T[] toArray(T[] a) {
if (a.length < size)
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(elementData, size, a.getClass());
System.arraycopy(elementData, 0, a, 0, size);
if (a.length > size)
a[size] = null;
return a;
}
// Positional Access Operations
@SuppressWarnings("unchecked")
E elementData(int index) {
return (E) elementData[index];
}
public E get(int index) {
Objects.checkIndex(index, size);
return elementData(index);
}
public E getFirst() {
if (size == 0) {
throw new NoSuchElementException();
} else {
return elementData(0);
}
}
public E getLast() {
int last = size - 1;
if (last < 0) {
throw new NoSuchElementException();
} else {
return elementData(last);
}
}
public E set(int index, E element) {
Objects.checkIndex(index, size);
E oldValue = elementData(index);
elementData[index] = element;
return oldValue;
}
private void add(E e, Object[] elementData, int s) {
if (s == elementData.length)
elementData = grow();
elementData[s] = e;
size = s + 1;
}
public boolean add(E e) {
modCount++;
add(e, elementData, size);
return true;
}
public void add(int index, E element) {
rangeCheckForAdd(index);
modCount++;
final int s;
Object[] elementData;
if ((s = size) == (elementData = this.elementData).length)
elementData = grow();
System.arraycopy(elementData, index,
elementData, index + 1,
s - index);
elementData[index] = element;
size = s + 1;
}
public void addFirst(E element) {
add(0, element);
}
public void addLast(E element) {
add(element);
}
public E remove(int index) {
Objects.checkIndex(index, size);
final Object[] es = elementData;
@SuppressWarnings("unchecked") E oldValue = (E) es[index];
fastRemove(es, index);
return oldValue;
}
public E removeFirst() {
if (size == 0) {
throw new NoSuchElementException();
} else {
Object[] es = elementData;
@SuppressWarnings("unchecked") E oldValue = (E) es[0];
fastRemove(es, 0);
return oldValue;
}
}
public E removeLast() {
int last = size - 1;
if (last < 0) {
throw new NoSuchElementException();
} else {
Object[] es = elementData;
@SuppressWarnings("unchecked") E oldValue = (E) es[last];
fastRemove(es, last);
return oldValue;
}
}
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof List)) {
return false;
}
final int expectedModCount = modCount;
// ArrayList can be subclassed and given arbitrary behavior, but we can
// still deal with the common case where o is ArrayList precisely
boolean equal = (o.getClass() == ArrayList.class)
? equalsArrayList((ArrayList<?>) o)
: equalsRange((List<?>) o, 0, size);
checkForComodification(expectedModCount);
return equal;
}
boolean equalsRange(List<?> other, int from, int to) {
final Object[] es = elementData;
if (to > es.length) {
throw new ConcurrentModificationException();
}
var oit = other.iterator();
for (; from < to; from++) {
if (!oit.hasNext() || !Objects.equals(es[from], oit.next())) {
return false;
}
}
return !oit.hasNext();
}
private boolean equalsArrayList(ArrayList<?> other) {
final int otherModCount = other.modCount;
final int s = size;
boolean equal;
if (equal = (s == other.size)) {
final Object[] otherEs = other.elementData;
final Object[] es = elementData;
if (s > es.length || s > otherEs.length) {
throw new ConcurrentModificationException();
}
for (int i = 0; i < s; i++) {
if (!Objects.equals(es[i], otherEs[i])) {
equal = false;
break;
}
}
}
other.checkForComodification(otherModCount);
return equal;
}
private void checkForComodification(final int expectedModCount) {
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
public int hashCode() {
int expectedModCount = modCount;
int hash = hashCodeRange(0, size);
checkForComodification(expectedModCount);
return hash;
}
int hashCodeRange(int from, int to) {
final Object[] es = elementData;
if (to > es.length) {
throw new ConcurrentModificationException();
}
int hashCode = 1;
for (int i = from; i < to; i++) {
Object e = es[i];
hashCode = 31 * hashCode + (e == null ? 0 : e.hashCode());
}
return hashCode;
}
public boolean remove(Object o) {
final Object[] es = elementData;
final int size = this.size;
int i = 0;
found: {
if (o == null) {
for (; i < size; i++)
if (es[i] == null)
break found;
} else {
for (; i < size; i++)
if (o.equals(es[i]))
break found;
}
return false;
}
fastRemove(es, i);
return true;
}
private void fastRemove(Object[] es, int i) {
modCount++;
final int newSize;
if ((newSize = size - 1) > i)
System.arraycopy(es, i + 1, es, i, newSize - i);
es[size = newSize] = null;
}
public void clear() {
modCount++;
final Object[] es = elementData;
for (int to = size, i = size = 0; i < to; i++)
es[i] = null;
}
public boolean addAll(Collection<? extends E> c) {
Object[] a = c.toArray();
modCount++;
int numNew = a.length;
if (numNew == 0)
return false;
Object[] elementData;
final int s;
if (numNew > (elementData = this.elementData).length - (s = size))
elementData = grow(s + numNew);
System.arraycopy(a, 0, elementData, s, numNew);
size = s + numNew;
return true;
}
public boolean addAll(int index, Collection<? extends E> c) {
rangeCheckForAdd(index);
Object[] a = c.toArray();
modCount++;
int numNew = a.length;
if (numNew == 0)
return false;
Object[] elementData;
final int s;
if (numNew > (elementData = this.elementData).length - (s = size))
elementData = grow(s + numNew);
int numMoved = s - index;
if (numMoved > 0)
System.arraycopy(elementData, index,
elementData, index + numNew,
numMoved);
System.arraycopy(a, 0, elementData, index, numNew);
size = s + numNew;
return true;
}
protected void removeRange(int fromIndex, int toIndex) {
if (fromIndex > toIndex) {
throw new IndexOutOfBoundsException(
outOfBoundsMsg(fromIndex, toIndex));
}
modCount++;
shiftTailOverGap(elementData, fromIndex, toIndex);
}
private void shiftTailOverGap(Object[] es, int lo, int hi) {
System.arraycopy(es, hi, es, lo, size - hi);
for (int to = size, i = (size -= hi - lo); i < to; i++)
es[i] = null;
}
private void rangeCheckForAdd(int index) {
if (index > size || index < 0)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private String outOfBoundsMsg(int index) {
return "Index: "+index+", Size: "+size;
}
private static String outOfBoundsMsg(int fromIndex, int toIndex) {
return "From Index: " + fromIndex + " > To Index: " + toIndex;
}
public boolean removeAll(Collection<?> c) {
return batchRemove(c, false, 0, size);
}
public boolean retainAll(Collection<?> c) {
return batchRemove(c, true, 0, size);
}
boolean batchRemove(Collection<?> c, boolean complement, final int from, final int end) {
Objects.requireNonNull(c);
final Object[] es = elementData;
int r;
// Optimize for initial run of survivors
for (r = from;; r++) {
if (r == end)
return false;
if (c.contains(es[r]) != complement)
break;
}
int w = r++;
try {
for (Object e; r < end; r++)
if (c.contains(e = es[r]) == complement)
es[w++] = e;
} catch (Throwable ex) {
// Preserve behavioral compatibility with AbstractCollection,
// even if c.contains() throws.
System.arraycopy(es, r, es, w, end - r);
w += end - r;
throw ex;
} finally {
modCount += end - w;
shiftTailOverGap(es, w, end);
}
return true;
}
@java.io.Serial
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
// Write out element count, and any hidden stuff
int expectedModCount = modCount;
s.defaultWriteObject();
// Write out size as capacity for behavioral compatibility with clone()
s.writeInt(size);
// Write out all elements in the proper order.
for (int i=0; i<size; i++) {
s.writeObject(elementData[i]);
}
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
@java.io.Serial
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
// Read in size, and any hidden stuff
s.defaultReadObject();
// Read in capacity
s.readInt(); // ignored
if (size > 0) {
// like clone(), allocate array based upon size not capacity
SharedSecrets.getJavaObjectInputStreamAccess().checkArray(s, Object[].class, size);
Object[] elements = new Object[size];
// Read in all elements in the proper order.
for (int i = 0; i < size; i++) {
elements[i] = s.readObject();
}
elementData = elements;
} else if (size == 0) {
elementData = EMPTY_ELEMENTDATA;
} else {
throw new java.io.InvalidObjectException("Invalid size: " + size);
}
}
public ListIterator<E> listIterator(int index) {
rangeCheckForAdd(index);
return new ListItr(index);
}
public ListIterator<E> listIterator() {
return new ListItr(0);
}
public Iterator<E> iterator() {
return new Itr();
}
public List<E> subList(int fromIndex, int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
return new SubList<>(this, fromIndex, toIndex);
}
@Override
public void forEach(Consumer<? super E> action) {
Objects.requireNonNull(action);
final int expectedModCount = modCount;
final Object[] es = elementData;
final int size = this.size;
for (int i = 0; modCount == expectedModCount && i < size; i++)
action.accept(elementAt(es, i));
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
@Override
public Spliterator<E> spliterator() {
return new ArrayListSpliterator(0, -1, 0);
}
@Override
public boolean removeIf(Predicate<? super E> filter) {
return removeIf(filter, 0, size);
}
boolean removeIf(Predicate<? super E> filter, int i, final int end) {
Objects.requireNonNull(filter);
int expectedModCount = modCount;
final Object[] es = elementData;
// Optimize for initial run of survivors
for (; i < end && !filter.test(elementAt(es, i)); i++)
;
// Tolerate predicates that reentrantly access the collection for
// read (but writers still get CME), so traverse once to find
// elements to delete, a second pass to physically expunge.
if (i < end) {
final int beg = i;
final long[] deathRow = nBits(end - beg);
deathRow[0] = 1L; // set bit 0
for (i = beg + 1; i < end; i++)
if (filter.test(elementAt(es, i)))
setBit(deathRow, i - beg);
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
modCount++;
int w = beg;
for (i = beg; i < end; i++)
if (isClear(deathRow, i - beg))
es[w++] = es[i];
shiftTailOverGap(es, w, end);
return true;
} else {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
return false;
}
}
@Override
public void replaceAll(UnaryOperator<E> operator) {
replaceAllRange(operator, 0, size);
// TODO(8203662): remove increment of modCount from ...
modCount++;
}
private void replaceAllRange(UnaryOperator<E> operator, int i, int end) {
Objects.requireNonNull(operator);
final int expectedModCount = modCount;
final Object[] es = elementData;
for (; modCount == expectedModCount && i < end; i++)
es[i] = operator.apply(elementAt(es, i));
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
@Override
@SuppressWarnings("unchecked")
public void sort(Comparator<? super E> c) {
final int expectedModCount = modCount;
Arrays.sort((E[]) elementData, 0, size, c);
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
modCount++;
}
}