package core.array;
/**
* Copyright (c) 2020 bigdata ALL Rights Reserved
* Project: learning
* Package: base.array
* Version: 1.0
*
* @author qingzhi.wu 2020/7/10 9:57
*/
public class MyArrayList<E> {
private E[] data;
private int size;
/**
* 构造函数,传入数组的容量capacity构造MyArrayList
*
* @param capacity
*/
public MyArrayList(int capacity) {
data = (E[])new Object[capacity];
size = 0;
}
/**
* 无参构造方法,默认容量为10
*/
public MyArrayList() {
this(10);
}
/**
* 获取数组汇总的元素个数
*
* @return
*/
public int getSize() {
return size;
}
/**
* 获取数组的容量
*
* @return
*/
public int getCapacity() {
return data.length;
}
public boolean isEmpty() {
return getSize() == 0;
}
public void addFirst(E e) {
add(0, e);
}
public void addLast(E e) {
add(size, e);
}
public void add(int index, E e) {
if (index < 0 || index > size)
throw new IllegalArgumentException("AddLast 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++;
}
private void resize(int capacity) {
E[] arr = (E[])new Object[capacity];
System.arraycopy(data,0,arr,0,size);
data = arr;
}
void set(int index, E e) {
if (index < 0 || index >= size)
throw new IllegalArgumentException("Get failed");
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] == e)
return i;
}
return -1;
}
public E remove(int index) {
if (index < 0 || index >= size)
throw new IllegalArgumentException("Delete failed");
E ret = get(index);
for (int i = index + 1; i < size; i++) {
data[i - 1] = data[i];
}
size--;
data[size] = null;
if(size < data.length/2){
resize(data.length/2);
}
return ret;
}
public E get(int index) {
if (index < 0 || index >= size)
throw new IllegalArgumentException("Get failed");
return data[index];
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append(String.format("Array:size = %d,capacity = %d\n", size, getCapacity()));
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 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);
}
}
}
数据结构-动态数组(java)
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转载自blog.csdn.net/weixin_43704599/article/details/107255883
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