Java:ArrayList ^ 2到int [] []

Question

我有这个arrayList:

 ArrayList<ArrayList<Integer>> temporary = new ArrayList<ArrayList<Integer>>();

一些我需要如何将其转换为int [] []

我有某种循环吗？

               for(ArrayList<Integer> item: temporary) {
                    //Here??

                }

干杯!

因为数组不是动态的(或者你称之为),我陷入困境.

Answer 1

这应该工作:

final int N = temporary.size();
int[][] a = new int[N][];
for (int i = 0; i < N; ++i) {
    final ArrayList<Integer> item = temporary.get(i);
    final int M = item.size();
    a[i] = new int[M];
    for (int j = 0; j < M; ++j) {
        a[i][j] = item.get(j); // assumes no null elements!
    }
}