This complete mini program code answers this question in quite self-explanatory way.

Just paste and run it.

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import java.util.ArrayList;

import java.util.List;

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public class ListTo2Darray {

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    public String[][] toArray(List<List<?>> list) {

    String[][] r = new String[list.size()][];

    int i = 0;

    for (List<?> next : list) {

       r[i++] = next.toArray(new String[next.size()]);

    }

    return r;

}

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    public static void main(String[]arg){

        String[][] sham;

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        List<List<?>> mList = new ArrayList();

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        List<String> a= new ArrayList();

        List<String> b= new ArrayList();

        a.add("a");  a.add("a");

        b.add("b");  b.add("b");

        mList.add(a); mList.add(b); 

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        ListTo2Darray mt= new ListTo2Darray();

        sham = mt.toArray(mList);

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        System.out.println(sham[0][0]);

        System.out.println(sham[0][1]);

        System.out.println(sham[1][0]);

        System.out.println(sham[1][1]);

    }

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}

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