模仿java集合容器之ArrayList - 黑马程序员技术交流社区

/**
* Title: ILinearList.java
* Description: 线性表抽象接口
* Copyright: Copyright (c) 2015
* @author possible
* @version 1.0
*/
package com.dt.linearlist;
public interface ILinearList<T> {
// /**
// * 初始化线性表
// *
// * @return 返回线性表引用
// */
// public T initList();
/**
* 删除线性表
*
* @return 返回true 销毁成功 false失败
*/
public void destoryList();
/**
* 判断线性表是否为空
*
* @return true 链表为空. false 链表不为空
*/
public boolean isEmpty();
/**
* 线性表长度
*
* @return 链表长度
*/
public int length();
/**
* 获取指定索引线性表结点
*
* @param index
* 获取index位置的元素
* @return 返回元素 T
*/
public T get(int index);
/**
* 在指定位置插入元素
*
* @param i
* 插入位置的索引
* @param t
* 插入的元素
* @return true 插入成功, false 插入失败
*/
public boolean add(int index, T t);
/**
* 删除指定索引的元素
*
* @param i
* 删除指定位置的元素
* @return true 删除成功; false 删除失败
*/
public T delete(int index);
/**
* 线性表遍历
*
* @return 返回遍历结果
*/
public String traverse();
/**
* 插入元素结点.
*
* @param t
* 插入结点
* @return true 插入成功 ; false 插入失败
*/
public boolean add(T t);
}

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/**
* Title: ArrayLinearList.java
* Description:模仿ArrayList
* @author possible
* @version 1.0
*/
package com.dt.linearlist;
import java.util.Arrays;
/**
* @author possible
*
*/
public class ArrayLinearList<T> implements ILinearList<T> {
/**
* 扩大容量的加载因子
*/
private static final float LOADER_FACTOR = 0.8f;
/**
* 初始化容量
*/
private static final int INITITAL_CAPACITY = 3;
/**
* 顺序表中真实存放的元素的个数
*/
private int length;
/**
* 容量
*/
private int capacity;
private Object[] elements;
public ArrayLinearList() {
this(INITITAL_CAPACITY);
}
public ArrayLinearList(int inititalCapacity) {
elements = new Object[inititalCapacity];
this.capacity = inititalCapacity;
}
@Override
public void destoryList() {
for (int i = 0, len = elements.length; i < len; i++) {
elements[i] = null;
}
length = 0;
}
@Override
public boolean isEmpty() {
return length == 0;
}
@Override
public int length() {
System.out.println("length = "+length+" capacity = "+capacity);
return length;
}
@SuppressWarnings("unchecked")
@Override
public T get(int index) {
if (!checkBounds(index)) {
throw new ArrayIndexOutOfBoundsException(checkBoundsMsg(index));
}
return (T) elements[index];
}
@Override
public boolean add(int index, T t) {
if (!checkBounds(index)) {
throw new ArrayIndexOutOfBoundsException(checkBoundsMsg(index));
}
if (isExtendCapacity()) {
extendCapacity();
}
System.arraycopy(elements, index, elements, index+1, length-index+1);
elements[index] = t;
length ++;
return true;
}
@Override
public T delete(int index) {
if (!checkBounds(index)) {
throw new ArrayIndexOutOfBoundsException(checkBoundsMsg(index));
}
@SuppressWarnings("unchecked")
T t = (T) elements[index];
System.arraycopy(elements, index+1, elements, index, length-index-1);
length--;
return t;
}
@Override
public String traverse() {
StringBuffer sb = new StringBuffer();
sb.append("开始遍历顺序表");
sb.append("\n");
for (int i = 0, len = length; i < len; i++) {
if(elements[i] == null){
break;
}
sb.append(elements[i].toString());
sb.append("\n");
}
sb.append("结束遍历顺序表");
System.out.println(sb.toString());
return sb.toString();
}
@Override
public boolean add(T t) {
if (isExtendCapacity()) {
extendCapacity();
}
elements[length++] = t;
return true;
}
private String checkBoundsMsg(int index) {
if (index >= length) {
return "下标越界 " + " length: " + length + " index: " + index;
}
return null;
}
/**
* 检查指定的索引是否越界
*
* @param index
* @return
*/
private boolean checkBounds(int index) {
return index >= 0 && index < length;
}
/**
* 判断是否需要扩大容量
*/
private boolean isExtendCapacity() {
if (length > capacity * LOADER_FACTOR) {
return true;
}
return false;
}
/**
* 扩展容量
*/
private void extendCapacity() {
System.out.println("扩大容量");
int newLength = capacity * 2;
elements = Arrays.copyOf(elements, newLength);
capacity = newLength;
}
}

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