Java数组指定位置插入元素：正确实现右移操作

public void insertAtRank(int r, Object o) {
    // 假设arrayVetor是底层数组，length是其容量
    // 错误之处在于循环方向
    for(int i = r + 1; i < arrayVetor.length; i++ ){
        arrayVetor[i] = arrayVetor[i-1];
    }
    this.arrayVetor[r] = o;
}

import java.util.Arrays;

public class DynamicArray {
    private Object[] arrayVetor;
    private int size; // 实际存储的元素数量
    private static final int DEFAULT_CAPACITY = 10;

    public DynamicArray() {
        this.arrayVetor = new Object[DEFAULT_CAPACITY];
        this.size = 0;
    }

    public DynamicArray(int capacity) {
        if (capacity < 0) {
            throw new IllegalArgumentException("Capacity cannot be negative.");
        }
        this.arrayVetor = new Object[capacity];
        this.size = 0;
    }

    /**
     * 在指定位置插入元素
     * @param r 插入的索引位置
     * @param o 要插入的元素
     * @throws IndexOutOfBoundsException 如果索引r无效
     * @throws IllegalStateException 如果数组已满
     */
    public void insertAtRank(int r, Object o) {
        // 1. 检查数组是否已满
        if (size == arrayVetor.length) {
            // 这里可以实现扩容逻辑，为了教程简洁，暂时抛出异常
            throw new IllegalStateException("Array is full, cannot insert more elements.");
        }

        // 2. 检查插入索引是否有效
        // r必须在 [0, size] 范围内
        if (r < 0 || r > size) {
            throw new IndexOutOfBoundsException("Index: " + r + ", Size: " + size);
        }

        // 3. 从最后一个元素开始，向后移动直到插入点r
        // 注意：循环条件是 i >= r，因为arrayVetor[r]的值也需要被移动到arrayVetor[r+1]
        for (int i = size - 1; i >= r; i--) {
            arrayVetor[i + 1] = arrayVetor[i];
        }

        // 4. 插入新元素
        arrayVetor[r] = o;

        // 5. 更新实际元素数量
        size++;
    }

    /**
     * 获取数组的字符串表示，只显示实际存储的元素
     * @return 数组内容的字符串
     */
    @Override
    public String toString() {
        // 创建一个只包含实际元素的子数组，然后转换为字符串
        Object[] actualElements = new Object[size];
        System.arraycopy(arrayVetor, 0, actualElements, 0, size);
        return Arrays.toString(actualElements);
    }

    /**
     * 获取底层数组的完整视图（包括null值）
     * @return 底层数组的完整字符串表示
     */
    public String toFullString() {
        return Arrays.toString(arrayVetor);
    }

    // 用于测试的main方法
    public static void main(String[] args) {
        DynamicArray array = new DynamicArray(10); // 容量为10的数组

        System.out.println("Initial array: " + array.toFullString() + ", Size: " + array.size);

        array.insertAtRank(0, "1");
        System.out.println("After insert 1 at 0: " + array.toFullString() + ", Size: " + array.size);

        array.insertAtRank(1, "2");
        System.out.println("After insert 2 at 1: " + array.toFullString() + ", Size: " + array.size);

        array.insertAtRank(2, "3");
        System.out.println("After insert 3 at 2: " + array.toFullString() + ", Size: " + array.size);

        array.insertAtRank(3, "4");
        System.out.println("After insert 4 at 3: " + array.toFullString() + ", Size: " + array.size);

        System.out.println("\nAttempting to insert 5 at index 2 (between 2 and 3)...");
        array.insertAtRank(2, "5"); // 在索引2处插入5
        System.out.println("After insert 5 at 2: " + array.toFullString() + ", Size: " + array.size);

        // 验证最终输出是否符合预期
        // 预期: [1, 2, 5, 3, 4, null, null, null, null, null]
    }
}

Initial array: [null, null, null, null, null, null, null, null, null, null], Size: 0
After insert 1 at 0: [1, null, null, null, null, null, null, null, null, null], Size: 1
After insert 2 at 1: [1, 2, null, null, null, null, null, null, null, null], Size: 2
After insert 3 at 2: [1, 2, 3, null, null, null, null, null, null, null], Size: 3
After insert 4 at 3: [1, 2, 3, 4, null, null, null, null, null, null], Size: 4

Attempting to insert 5 at index 2 (between 2 and 3)...
After insert 5 at 2: [1, 2, 5, 3, 4, null, null, null, null, null], Size: 5