合并排序在复制步骤中引发ArrayOutOfBounds错误

我正在尝试实现一种通用的合并排序算法，该算法使用临时数组来存储合并后的部分，然后复制排序后的数据。但是，该程序在复制转移步骤(最后一个while循环(中不断失败，并引发ArrayIndexOutOfBounds异常。我很困惑为什么会发生这种事！

我知道在这个程序中使用Array.copy更简单，但我正在尝试使用循环

public static <E extends Comparable<E>> void mergeSort2(E[] array) {
mergeSortHelper2(array, 0, array.length - 1);
}
private static <E extends Comparable<E>> void mergeSortHelper2(E[] array, int firstIndex, int lastIndex) {
if (firstIndex >= lastIndex) {
return;
}
//otherwise divide
int middle = (firstIndex + lastIndex) / 2;
//conquer with recursion
mergeSortHelper2(array, firstIndex, middle);
mergeSortHelper2(array, middle + 1, lastIndex);
//combine: take in the original array, and all indices
merge2(array, firstIndex, middle, middle + 1, lastIndex);
}
private static <E extends Comparable<E>> void merge2(E[] array, int leftFirst, int leftLast, int rightFirst, int rightLast) {
E[] temp = (E[]) Array.newInstance(array.getClass().getComponentType(), (rightLast - leftFirst + 1));
int indexLeft = leftFirst;
int indexRight = rightFirst;
int index = 0;
while (indexLeft <= leftLast && indexRight <= rightLast) {
if (array[indexLeft].compareTo(array[indexRight]) < 0) {
temp[index++] = array[indexLeft++];
}
else {
temp[index++] = array[indexRight++];
}
}
while (indexLeft <= leftLast) {
temp[index++] = array[indexLeft++];
}
while (indexRight <= rightLast) {
temp[index++] = array[indexRight++];
}
int newIndex = 0;
while (newIndex != temp.length - 1) {
array[newIndex++] = temp[newIndex++];
}
}