数据结构(底层实现+Java版本)
//基于Java的数组的二次封装(动态的)
//使用泛型(除基本类型外的所有类型)
public class Array<E> {
private E[] data; //存储数据
private int size; //有多少个有效的数据
//构造方法,传入数组容量
public Array(int capacity) {
data = (E[]) new Object[capacity]; //new不了泛型的的数组
size = 0;
}
//无参数的构造函数
public Array() {
this(10);
}
//获取数组中元素的个数
public int getSize() {
return size;
}
//获取数组的容量
public int getCapacity() {
return data.length;
}
//返回数组是否为空
public boolean isEmpty() {
return size == 0;
}
//向所有元素后添加一个新的元素
public void addLast(E e) {
add(size, e);
}
//向第一个位置插入元素
public void addFirst(E e) {
add(0, e);
}
//插入到指定位置
public void add(int index, E e) {
if (index < 0 || index > size) {
//参数错误
throw new IllegalArgumentException("Add failed,index>=0,and index<=size.");
}
if (size == data.length) {
resize(2 * data.length); //扩容2倍
}
for (int i = size - 1; i >= index; i--) {
data[i + 1] = data[i];
}
data[index] = e;
size++;
}
//扩容
private void resize(int newCapacity) {
E[] newData = (E[]) new Object[newCapacity]; //定义一个新的数组
for (int i = 0; i < size; i++) {
newData[i] = data[i];
}
data = newData;
}
//获取
public E get(int index) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Get failed,Index is Illegal");
}
return data[index];
}
public E getLast(){
return get(size-1);
} //不用data[size-1],防止数组越界
public E getFirst(){
return get(0);
}
//修改
public void set(int index, E e) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Get failed,Index is Illegal");
}
data[index] = e;
}
//查找数组中是否有元素e
public boolean contains(E e) {
for (int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return true;
}
}
return false;
}
//查找元素,并且返回数组的下标
public int find(E e) {
for (int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return i;
}
}
return -1; //位置不合法
}
//删除某一个元素,返回删除的元素
public E remove(int index) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("remove failed,Index is Illegal");
}
E rem = data[index];
for (int i = index + 1; i < size; i++) {
data[i - 1] = data[i];
}
size--;
data[size] = null;
//缩容
if (size == data.length / 4 && data.length != 0) {
resize(data.length / 2);
}
return rem;
}
public E removeFirst() {
return remove(0);
}
public E removeLast() {
return remove(size - 1);
}
//从数组中删除元素e
public void removeElement(E e) {
int index = find(e);
if (index != -1) {
remove(index);
}
}
@Override //输出数组类(某个对象)的详细信息
public 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();
}
}