public class Array<E> {private E[] data;private int size;// 构造函数public Array(int Capacity){data = (E[])new Object[Capacity];size = 0;}// 默认构造函数public Array(){this(10);}// 判断数组是否已满public boolean isFull(){return size == data.length;}// 判断数组是否为空public boolean isEmpty(){return size == 0;}// 找出元素 e 的下标，没有返回 -1public int find(E e){for(int i = 0; i < size; i++){if(data[i].equals(e)){return i;}}return -1;}// 判断数组是否包含元素 epublic boolean contain(E e){return find(e) == -1 ? false : true ;}// 获取数组的大小 sizepublic int getSize(){return size;}// 获取数组的容量 Capacitypublic int getCapacity(){return data.length;}// 获取下标为 index 位置的元素 epublic E get(int index){// 判断传入下标是否合法if(index < 0 || index >= size){throw new IllegalArgumentException("Get Failed! Index is illegal!");}return data[index];}// 获取数组的第一个元素public E getFirst(){return get(0);}// 获取数组的最后一个元素public E getLast(){return get(size - 1);}// 设置下标 index 位置处的元素为 epublic void set(int index, E e){// 判断传入下标是否合法if(index < 0 || index >= size){throw new IllegalArgumentException("Set Failed! Index is illegal!");}data[index] = e;}// 在下标为 index 位置插入元素 epublic void add(int index, E e){// 判断传入下标是否合法if(index < 0 || index > size){throw new IllegalArgumentException("Add Failed! Index is illegal!");}// 如果数组已满，则重新分配空间if (isFull()){resize(data.length * 2);}// 在 index 位置插入元素 efor (int i = size - 1; i >= index; i--){data[i + 1] = data[i];}data[index] = e;size++;}// 在数组头插入元素 epublic void addFirst(E e){add(0, e);}// 在数组尾插入元素 epublic void addLast(E e){add(size, e);}// 删除下标为 index 位置处的元素public E remove(int index){// 判断下标是否合法if (index < 0 || index >= size){throw new IllegalArgumentException("Remove Failed! Index is illegal!");}E tmp = data[index];for(int i = index; i < size - 1; i++){data[i] = data[i + 1];}size--;// 判断是否需要重新分配空间if (size == data.length / 4 && data.length / 2 != 0){resize(data.length / 2);}return tmp;}// 删除数组头部元素public E removeFirst(){return remove(0);}// 删除数组尾部元素public E removeLast(){return remove(size - 1);}// 删除元素 epublic void removeElement(E e){int index = find(e);if (index != -1){remove(index);}}// 重新分配空间大小public void resize(int newCapacity){if (newCapacity <= 0){throw new IllegalArgumentException("Resize Failed! NewCapacity is illegal!");}E[] newData = (E[])new Object[newCapacity];for (int i = 0; i < size; i++){newData[i] = data[i];}data = newData;}// 重载打印函数@Overridepublic String toString(){StringBuilder res = new StringBuilder();res.append(String.format("Array size = %d, Capacity = %d\n", size, data.length));res.append("[");for (int i = 0; i < size; i++){res.append(data[i]);if (i != size - 1)res.append(", ");}res.append("]");return res.toString();}public static void main(String[] args){Array<Integer> arr = new Array<>();for(int i = 0 ; i < 10 ; i ++)arr.addLast(i);System.out.println(arr);arr.add(1, 100);System.out.println(arr);arr.addFirst(-1);System.out.println(arr);arr.remove(2);System.out.println(arr);arr.removeElement(4);System.out.println(arr);arr.removeFirst();System.out.println(arr);for(int i = 0 ; i < 4 ; i ++){arr.removeFirst();System.out.println(arr);}}
}