public class Array {
private E[] data;
private int size;
/**
* æž„é€ å‡½æ•°ï¼Œä¼ å…¥æ•°ç»„çš„å®¹é‡ capacity æž„é€ Array
*
* @param capacity
*/
public Array(int capacity) {
data = (E[]) new Object[capacity]; // new E[capacity] ä¸æ”¯æŒè¯¥è¯æ³•ï¼ŒåŽ†å²é—留问题
size = 0;
}
// æ— å‚æ•°çš„æž„é€ å‡½æ•°ï¼Œé»˜è®¤æ•°ç»„çš„å®¹é‡ capacity=10
public Array() {
this(10);
}
// 获å–数组ä¸çš„å…ƒç´ ä¸ªæ•°
public int getSize() {
return size;
}
// 获å–数组的容é‡
public int getCapacity() {
return data.length;
}
// 返回数组是å¦ä¸ºç©º
public boolean isEmpty() {
return size == 0;
}
// å‘æ‰€æœ‰å…ƒç´ åŽæ·»åŠ 一个新元ç´
public void addLast(E e) {
/*if (size == data.length) {
throw new IllegalArgumentException("AddLast failed. Array is full.");
}
data[size] = e;
size++;*/
add(size, e);
}
// åœ¨æ‰€æœ‰å…ƒç´ å‰æ·»åŠ 一个新元ç´
public void addFirst(E e) {
add(0, e);
}
// 在第 index 个ä½ç½®æ’å…¥ä¸€ä¸ªæ–°å…ƒç´ e
public void add(int index, E e) {
if (index < 0 || index > size) {
throw new IllegalArgumentException("add failed. Require index >=0 and index < size.");
}
if (size == data.length) {
resize(2 * data.length);
}
for (int i = size - 1; i >= index; i--) {
data[i + 1] = data[i];
}
data[index] = e;
size++;
}
//èŽ·å– index 索引ä½ç½®çš„å…ƒç´
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);
}
public E getFirst() {
return get(0);
}
// 修改 index 索引ä½ç½®çš„å…ƒç´
public void set(int index, E e) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Set failed. Index is illegal.");
}
data[index] = e;
}
// 查找数组ä¸æ˜¯å¦æœ‰å…ƒç´ e
public boolean contains(E e) {
for (int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return true;
}
}
return false;
}
// 查找数组ä¸å…ƒç´ e 所在的索引，如果ä¸å˜åœ¨å…ƒç´ e，则返回 -1
public int find(E e) {
for (int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return i;
}
}
return -1;
}
// 从数组ä¸åˆ 除 index ä½ç½®çš„å…ƒç´ ï¼Œè¿”å›žåˆ é™¤çš„å…ƒç´
public E remove(int index) {
if (index < 0 || index > size) {
throw new IllegalArgumentException("remove failed. Index is illegal.");
}
E ret = data[index];
for (int i = index + 1; i < size; i++) {
data[i - 1] = data[i];
}
size--;
// 该行å¯é€‰
data[size] = null; // loitering objects != memory leak
if (size == data.length / 4 && data.length / 2 != 0) {
resize(data.length / 2);
}
return ret;
}
// 从数组ä¸åˆ é™¤ç¬¬ä¸€ä¸ªå…ƒç´ ï¼Œè¿”å›žåˆ é™¤çš„å…ƒç´
public E removeFirst() {
return remove(0);
}
// 从数组ä¸åˆ 除最åŽå…ƒç´ ï¼Œè¿”å›žåˆ é™¤çš„å…ƒç´
public E removeLast() {
return remove(size - 1);
}
// 从数组ä¸åˆ é™¤å…ƒç´ e
public void removeElement(E e) {
int index = find(e);
if (index != -1) {
remove(index);
}
}
@Override
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();
}
private void resize(int newCapacity) {
E[] newData = (E[]) new Object[newCapacity];
for (int i = 0; i < size; i++) {
newData[i] = data[i];
}
data = newData;
}
}