如何转换ArrayList <arraylist <string>＆gt; to String [] []？</arraylist <string>

Question

您可以使用

将ArrayList<String>转换为String[]

ArrayList<String> stringList = new ArrayList<String>();
stringList.add("one");
stringList.add("two");
String[] strings1 = Arrays.copyOf(stringList.toArray(), stringList.toArray().length, String[].class);

但是如何将ArrayList<ArrayList<String>>转换为String[][]？

ArrayList<ArrayList<String>> listOfStringLists = new ArrayList<ArrayList<String>>();

Answer 1

String[][] strings2 = convertStringArrayList(listOfStringLists);

将ArrayList<ArrayList<String>>转换为String[][]方法：

private String[][] convertStringArrayList( ArrayList<ArrayList<String>> listOfStringLists ) {
    String[][] stringGroups = new String[listOfStringLists.size()][];
    for ( int i=0; i< listOfStringLists.size(); i++ ) {
        ArrayList<String> stringArray = listOfStringLists.get(i);
        String[] stringsChildren = Arrays.copyOf(stringArray.toArray(), stringArray.toArray().length, String[].class);
        stringGroups[i] = stringsChildren;
    }
    return stringGroups;
}