ArrayList.java

package com.github.eutkin;

@SuppressWarnings("UNCHECKED_CAST")
public class ArrayList<T> implements List<T> {

    private Object[] array;

    private int size;


    public ArrayList(int initialCapacity) {
        this.array = new Object[initialCapacity];
        this.size = 0;
    }

    @Override
    public T get(int index) {
        return (T) this.array[index];
    }

    @Override
    public void add(T element) {
        this.array[this.size] = element;
        this.size++;
        if (this.array.length == this.size) {
            resize(size * 2);
        }
    }

    @Override
    public void remove(int index) {
        this.array[index] = null;
        // все сложнее
    }

    private void resize(int capacity) {
        Object[] newArray = new Object[capacity];
        System.arraycopy(this.array, 0, newArray, 0, this.array.length);
        this.array = newArray;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("[");
        for (int i = 0; i < this.size - 1; i++) {
            sb.append(this.array[i]);
            sb.append(',');
        }
        sb.append(this.array[this.size - 1]);
        return sb.append(']').toString();
    }
}