java底层实现容器

 1 package StudyCollection; 2  3 /** 4  * 底层实现简单容器 5  *  6  * @author ouyang-an 谢谢尚学堂 高琪 老师 7  */ 8  9 public class MakeArray {10     PRivate Object[] elementData;11     private int size;12 13     // 无参构造器14     public MakeArray() {15         this(10);  //这里默认大小是1016     }17 18     // 带参构造器19     public MakeArray(int initialCapacity) {20         if (initialCapacity < 0) {21             try {22                 throw new Exception("数组越界了!");23             } catch (Exception e) {24                 e.printStackTrace();25             }26         }27         elementData = new Object[initialCapacity];28     }29 30     // add()方法31     public void add(Object obj) {32         if (size == elementData.length) {33             Object[] newArray = new Object[size * 2];34             System.arraycopy(elementData, 0, newArray, 0,35                     elementData.length);36             elementData = newArray;37         }38         elementData[size] = obj;39         size++;40     }41 42     // size方法43     public int size() {44         return size;45     }46 47     // 判断数组是否为空48     public boolean isEmpty() {49         return size == 0;50     }51 52     // 遍历53     public void iteratesMethod() {54         for (int i = 0; i < size; i++) {55             Object array_element = elementData[i];56             System.out.println(i + ":   " + array_element);57         }58     }59 60     // get方法61     public Object get(int index) {62         if (index >= size) {63             try {64                 throw new Exception();65             } catch (Exception e) {66                 e.printStackTrace();67             }68         }69         return elementData[index];70     }71 72     // set方法73     public Object set(int index, Object nObject) {74         return elementData[index] = nObject;75     }76 77     public static void main(String[] args) {78         MakeArray list = new MakeArray();79         list.add("11");80         list.add("22");81         list.add("33");82         list.add("44");83         list.iteratesMethod();84         System.out.println("------------------------");85         System.out.println(list.size);86         System.out.println("------------------------");87         System.out.println(list.isEmpty());88         System.out.println("------------------------");89         System.out.println(list.get(3));90         System.out.println("------------------------");91         System.out.println(list.set(2, "ouyangan"));92         System.out.println("------------------------");93         list.iteratesMethod();94     }95 }