将 ArrayList 转换为包含不同长度数组的二维数组 [英] Convert ArrayList into 2D array containing varying lengths of arrays

问题描述

所以我有:

ArrayList<ArrayList<String>> 

其中包含 x 个数组列表，其中包含另一个 y 个字符串.. 演示:

Which contains an x number of ArrayLists which contain another y number of Strings.. To demonstrate:

Index 0:
  String 1
  String 2
  String 3
Index 1:
  String 4
Index 2:
Index 3:
  String 5
  String 6

其中 index 是指包含字符串的数组索引.

Where index refers to the array index containing a string.

如何将其转换为如下所示的二维数组:

How can I transform this into a 2D array which looks like:

{{String1, String2, String3},{String4}, {}, {String5, String6}}

非常感谢.

推荐答案

String[][] array = new String[arrayList.size()][];
for (int i = 0; i < arrayList.size(); i++) {
    ArrayList<String> row = arrayList.get(i);
    array[i] = row.toArray(new String[row.size()]);
}

其中 arrayList 是您的 ArrayList>(或任何 List>，更改for 循环中的第一行相应地)

where arrayList is your ArrayList<ArrayList<String>> (or any List<List<String>>, change the first line inside the for loop accordingly)

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