java底层实现容器

package StudyCollection;

/**
 * 底层实现简单容器
 * 
 * @author ouyang-an 谢谢尚学堂 高琪 老师
 */

public class MakeArray {
    private Object[] elementData;
    private int size;

    // 无参构造器
    public MakeArray() {
        this(10);  //这里默认大小是10
    }

    // 带参构造器
    public MakeArray(int initialCapacity) {
        if (initialCapacity < 0) {
            try {
                throw new Exception("数组越界了!");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        elementData = new Object[initialCapacity];
    }

    // add()方法
    public void add(Object obj) {
        if (size == elementData.length) {
            Object[] newArray = new Object[size * 2];
            System.arraycopy(elementData, 0, newArray, 0,
                    elementData.length);
            elementData = newArray;
        }
        elementData[size] = obj;
        size++;
    }

    // size方法
    public int size() {
        return size;
    }

    // 判断数组是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    // 遍历
    public void iteratesMethod() {
        for (int i = 0; i < size; i++) {
            Object array_element = elementData[i];
            System.out.println(i + ":   " + array_element);
        }
    }

    // get方法
    public Object get(int index) {
        if (index >= size) {
            try {
                throw new Exception();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return elementData[index];
    }

    // set方法
    public Object set(int index, Object nObject) {
        return elementData[index] = nObject;
    }

    public static void main(String[] args) {
        MakeArray list = new MakeArray();
        list.add("11");
        list.add("22");
        list.add("33");
        list.add("44");
        list.iteratesMethod();
        System.out.println("------------------------");
        System.out.println(list.size);
        System.out.println("------------------------");
        System.out.println(list.isEmpty());
        System.out.println("------------------------");
        System.out.println(list.get(3));
        System.out.println("------------------------");
        System.out.println(list.set(2, "ouyangan"));
        System.out.println("------------------------");
        list.iteratesMethod();
    }
}