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package Implementations;

import java.util.Iterator;

public class ArrayList<T> implements List<T>, Iterable<T> {

private T[] array;

private int size = 0;

public ArrayList(){

array = (T[])new Object[3];

}

private void grow(){

T[] bigger = (T[])new Object[array.length * 3 / 2 + 1];

System.arraycopy(array, 0, bigger, 0, array.length);

array = bigger;

}

private void shrink(){

T[] smaller = (T[])new Object[size];

System.arraycopy(array, 0, smaller, 0, smaller.length);

array = smaller;

}

@Override

public void add(T item) {

if(array.length <= size)

grow();

array[size] = item;

size++;

}

@Override

public T get(int index) {

if(index >= size)

throw new IndexOutOfBoundsException();

return array[index];

}

@Override

public void remove(int index) {

if(index > size - 1)

throw new IndexOutOfBoundsException();

for (int i = index; i < size - 1; i++){

if(i == array.length - 1)

array[i] = null; //Todo: This seems to be not necessary

else

array[i] = array[i + 1];

}

size--;

//Shrink

if(array.length > size + (size * 3 / 2))

shrink();

}

@Override

public void clear() {

size = 0;

array = (T[])new Object[3];

}

@Override

public int getIndex(T item) {

for(int i = 0; i < size; i++)

if(array[i].equals(item))

return i;

return -1;

}

@Override

public int size() {

return size;

}

@Override

public void set(int index, T value) {

if(index >= size)

throw new IndexOutOfBoundsException();

array[index] = value;

}

@Override

public String toString() {

StringBuilder s = new StringBuilder();

for(int i = 0; i < size; i++) {

if(s.length() != 0)

s.append(", ");

s.append(array[i].toString());

}

return "[" + s.toString() + "]";

}

@Override

public Iterator<T> iterator() {

return new Iterator<T>() {

int currentIndex = 0;

@Override

public boolean hasNext() {

return currentIndex < size;

}

@Override

public T next() {

return array[currentIndex++];

}

};

}

}