public class GenericArray {
private T[] data;
private int size;
// æ ¹æ®ä¼ 入容é‡ï¼Œæž„é€ Array
public GenericArray(int capacity) {
data = (T[]) new Object[capacity];
size = 0;
}
// æ— å‚æž„é€ æ–¹æ³•ï¼Œé»˜è®¤æ•°ç»„å®¹é‡ä¸º10
public GenericArray() {
this(10);
}
// 获å–数组容é‡
public int getCapacity() {
return data.length;
}
// 获å–当å‰å…ƒç´ 个数
public int count() {
return size;
}
// 判æ–数组是å¦ä¸ºç©º
public boolean isEmpty() {
return size == 0;
}
// 修改 index ä½ç½®çš„å…ƒç´
public void set(int index, T e) {
checkIndex(index);
data[index] = e;
}
// 获å–对应 index ä½ç½®çš„å…ƒç´
public T get(int index) {
checkIndex(index);
return data[index];
}
// 查看数组是å¦åŒ…å«å…ƒç´ e
public boolean contains(T e) {
for (int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return true;
}
}
return false;
}
// 获å–å¯¹åº”å…ƒç´ çš„ä¸‹æ ‡, 未找到，返回 -1
public int find(T e) {
for ( int i = 0; i < size; i++) {
if (data[i].equals(e)) {
return i;
}
}
return -1;
}
// 在 index ä½ç½®ï¼Œæ’å…¥å…ƒç´ e, 时间å¤æ‚度 O(m+n)
public void add(int index, T e) {
checkIndexForAdd(index);
// 如果当å‰å…ƒç´ 个数ç‰äºŽæ•°ç»„容é‡ï¼Œåˆ™å°†æ•°ç»„扩容为原æ¥çš„2å€
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++;
}
// å‘数组头æ’入元ç´
public void addFirst(T e) {
add(0, e);
}
// å‘数组尾æ’入元ç´
public void addLast(T e) {
add(size, e);
}
// åˆ é™¤ index ä½ç½®çš„å…ƒç´ ï¼Œå¹¶è¿”å›ž
public T remove(int index) {
checkIndex(index);
T ret = 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 / 2 != 0) {
resize(data.length / 2);
}
return ret;
}
// åˆ é™¤ç¬¬ä¸€ä¸ªå…ƒç´
public T removeFirst() {
return remove(0);
}
// åˆ é™¤æœ«å°¾å…ƒç´
public T removeLast() {
return remove(size - 1);
}
// 从数组ä¸åˆ 除指定元ç´
public void removeElement(T e) {
int index = find(e);
if (index != -1) {
remove(index);
}
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append(String.format("Array size = %d, capacity = %d \n", size, data.length));
builder.append('[');
for (int i = 0; i < size; i++) {
builder.append(data[i]);
if (i != size - 1) {
builder.append(", ");
}
}
builder.append(']');
return builder.toString();
}
// 扩容方法，时间å¤æ‚度 O(n)
private void resize(int capacity) {
T[] newData = (T[]) new Object[capacity];
for (int i = 0; i < size; i++) {
newData[i] = data[i];
}
data = newData;
}
private void checkIndex(int index) {
if (index < 0 || index >= size) {
throw new IllegalArgumentException("Add failed! Require index >=0 and index < size.");
}
}
private void checkIndexForAdd(int index) {
if(index < 0 || index > size) {
throw new IllegalArgumentException("remove failed! Require index >=0 and index <= size.");
}
}
}