数组的基础实现
public class Array {
private int[] data;
private int size;
public Array(int capacity) {
data = new int[capacity];
size = 0;
}
public Array() {
this(10);
}
public int getSize() {
return size;
}
public int getCapacity() {
return data.length;
}
public boolean isEmpty() {
return size == 0;
}
public void addLast(int e) {
add(size, e);
}
public void addFirst(int e) {
add(0, e);
}
public void add(int index, int e) {
if(size == data.length) {
throw new IllegalArgumentException("容量错误!");
}else if(index < 0 || index > size){
throw new IllegalArgumentException("容量错误!");
}else{
for(int i = size - 1; i >= index; i-- ){
data[i + 1] = data[i];
}
data[index] = e;
size++;
}
}
public int get(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
return data[index];
}
public void set(int index, int e) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
data[index] = e;
}
public boolean contains(int e) {
for(int i = 0; i < size; i++) {
if(data[i] == e)
return true;
}
return false;
}
public int find(int e) {
for(int i = 0; i < size; i++) {
if(data[i] == e)
return i;
}
return -1;
}
public int remove(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
int ret = data[index];
for(int i = index + 1; i < size; i++){
data[i - 1] = data[i];
}
size--;
return ret;
}
public int removeFirst() {
return remove(0);
}
public int removeLast() {
return remove(size - 1);
}
public int removeElement(int e) {
int index = find(e);
if(index != -1)
return remove(index);
return -1;
}
@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();
}
}
进阶版数组(使用泛型)
public class Array<E> {
private E[] data;
private int size;
public Array(int capacity) {
data = (E[])new Object[capacity];
size = 0;
}
public Array() {
this(10);
}
public int getSize() {
return size;
}
public int getCapacity() {
return data.length;
}
public boolean isEmpty() {
return size == 0;
}
public void addLast(E e) {
add(size, e);
}
public void addFirst(E e) {
add(0, e);
}
public void add(int index, E e) {
if(size == data.length) {
throw new IllegalArgumentException("容量错误!");
}else if(index < 0 || index > size){
throw new IllegalArgumentException("容量错误!");
}else{
for(int i = size - 1; i >= index; i-- ){
data[i + 1] = data[i];
}
data[index] = e;
size++;
}
}
public E get(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
return data[index];
}
public void set(int index, E e) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
data[index] = e;
}
public boolean contains(E e) {
for(int i = 0; i < size; i++) {
if(data[i].equals(e))
return true;
}
return false;
}
public int find(E e) {
for(int i = 0; i < size; i++) {
if(data[i].equals(e))
return i;
}
return -1;
}
public E remove(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
E ret = data[index];
for(int i = index + 1; i < size; i++){
data[i - 1] = data[i];
}
size--;
data[size] = null;
return ret;
}
public E removeFirst() {
return remove(0);
}
public E removeLast() {
return remove(size - 1);
}
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();
}
}
终极版(动态数组)
public class Array<E> {
private E[] data;
private int size;
private void resize(int newCapacity) {
E[] newData = (E[])new Object[newCapacity];
for(int i = 0; i < size; i++) {
newData[i] = data[i];
}
data = newData;
}
public Array(int capacity) {
data = (E[])new Object[capacity];
size = 0;
}
public Array() {
this(10);
}
public int getSize() {
return size;
}
public int getCapacity() {
return data.length;
}
public boolean isEmpty() {
return size == 0;
}
public void addLast(E e) {
add(size, e);
}
public void addFirst(E e) {
add(0, e);
}
public void add(int index, E e) {
if(size == data.length) {
resize(2 * data.length);
}else if(index < 0 || index > size){
throw new IllegalArgumentException("容量错误!");
}else{
for(int i = size - 1; i >= index; i-- ){
data[i + 1] = data[i];
}
data[index] = e;
size++;
}
}
public E get(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
return data[index];
}
public void set(int index, E e) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
data[index] = e;
}
public boolean contains(E e) {
for(int i = 0; i < size; i++) {
if(data[i].equals(e))
return true;
}
return false;
}
public int find(E e) {
for(int i = 0; i < size; i++) {
if(data[i].equals(e))
return i;
}
return -1;
}
public E remove(int index) {
if(index < 0 || index >= size)
throw new IllegalArgumentException("容量错误!");
E ret = data[index];
for(int i = index + 1; i < size; i++){
data[i - 1] = data[i];
}
size--;
data[size] = null;
if(size == data.length / 4 && data.length / 2 != 0)
resize(data.length / 2);
return ret;
}
public E removeFirst() {
return remove(0);
}
public E removeLast() {
return remove(size - 1);
}
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();
}
}