【数据结构与算法 | 基础篇】模拟ArrayList实现的“动态数组“

public class SimulateArrayTest implements Iterable<Integer>{
    //数组
    private static int[] elementDate;
    //数组实际存储数据的个数.
    private static int size = 0;
    //数组的容量
    private static int capacity = 10;
 
    public SimulateArrayTest() {
        elementDate = null;
    }
    public void add(int value) {
        if (size == 0) {
            elementDate = new int[capacity];
        }
        //存储数组的个数大于等于了数组的容量
        //则需要进行扩容操作
        if (size > capacity) {
            Dilatation();
        }
        elementDate[size++] = value;
    }
    //数组扩容操作
    public static void Dilatation() {
        int newCapacity = capacity + capacity >> 1;
        int[] newElementData = new int[newCapacity];
        System.arraycopy(elementDate, 0, newElementData, 0, size);
        capacity = newCapacity;
    }
    //查取操作
    public Integer get(int index) {
        if (index <= size - 1){
            return elementDate[index];
        }
        throw new RuntimeException();
    }
    //改数据的操作
    public void get(int index, int value) {
        if (index >= 0 && index <= size - 1) {
            elementDate[index] = value;
        }
        throw new RuntimeException();
    }
    //删除操作, 两个重载的remove方法
    public int remove(int index) {
        if (size > 0 && index >= 0 && index <= size - 1) {
            //删除的元素不是数组的末尾的元素, 我们就要把后面的数组赋值贴过来
            if (index < size - 1){
                //System.arraycopy(Object src,  int  srcPos,Object dest, int destPos,int length);
                //可以用于复制数组, 从src的srcPos位置开始复制到dest的destPos开始的位置上, 复制元素的长度为length;
                System.arraycopy(elementDate, index + 1 , elementDate, index, size - index - 1);
            }
            int temp =  elementDate[index];
            size--;
            return temp;
        }
        throw new RuntimeException();
    }
    public void remove(Integer value) {
        for (int i = 0; i < size; i++) {
            if (elementDate[i] == value) {
                if (i < size - 1) {
                    System.arraycopy(elementDate, i + 1 , elementDate, i, size - i - 1);
                }
                size--;
            }
        }
    }
    //获取数组的长度
    public int length() {
        return size;
    }
    public static int count = 0;
 
    //遍历, 迭代器
    @Override
    public Iterator<Integer> iterator() {
        return new Iterator<Integer>() {
            @Override
            public boolean hasNext() {
                if (count < size) {
                    return true;
                }
                count = 0;
                return false;
            }
 
            @Override
            public Integer next() {
                return elementDate[count++];
            }
        };
    }
    public static void Traverse(Consumer<Integer> consumer) {
        for (int i = 0; i < size; i++) {
            consumer.accept(elementDate[i]);
        }
    }
}

@Test
    public void test() {
        SimulateArrayTest s = new SimulateArrayTest();
        s.add(12);
        s.add(23);
        s.add(34);
        s.add(45);
        s.add(56);
        s.add(67);
        s.Traverse(value -> {
            System.out.println(value);
        });
    }
 
控制台 : 
12
23
34
45
56
67