java - Arraylist 到 Array 的转换 - toArray() 函数推断类型不符合上限错误

Question

这是代码sinplet:

Excel excel = new Excel();
ArrayList<Integer> a1=excel.readExcelSheet("C:\\Users\\Madhukar\\Desktop\\Employee.xls");
        System.out.println("Using Iterator");
        Iterator iterator = a1.iterator();
        while (iterator.hasNext()) {
       System.out.println(iterator.next());}
        int x=a1.size();
        int[] a3=new int[x];
        a3=a1.toArray(a3);

这是错误信息:

no suitable method found for toArray(int[]) method AbstractCollection.toArray(T#1[]) is not applicable (inferred type does not conform to upper bound(s) inferred: int upper bound(s): Object)

  where T#1,T#2 are type-variable...

Answer 1

原语和泛型不匹配。您需要 Integer[] 而不是 int[]。