arrayList带参数的初始化，set（i，value）报错

List<Integer> path=new ArrayList<>(8);

path.set(2，1);

这段代码会出问题吗

答案是会的

public ArrayList(int initialCapacity) { if (initialCapacity > 0) { this.elementData = new Object[initialCapacity]; } else if (initialCapacity == 0) { this.elementData = EMPTY_ELEMENTDATA; } else { throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity); } }

带参数的构造方法如下，只是分配了空间，但是并没有给size（实际元素个数）赋值，但是在set（索引，值）这个方法的时候会判断当前的下标是不是小于size，所以会报错Index 0 out of bounds for length 0


set源码

public E set(int index, E element) { Objects.checkIndex(index, size); E oldValue = elementData(index); elementData[index] = element; return oldValue; }

--checkIndex调用方法

@ForceInline public static int checkIndex(int index, int length) { return Preconditions.checkIndex(index, length, null); }

-- 调用checkIndex

@IntrinsicCandidate public static <X extends RuntimeException> int checkIndex(int index, int length, BiFunction<String, List<Number>, X> oobef) { if (index < 0 || index >= length) throw outOfBoundsCheckIndex(oobef, index, length); return index; }