LinkedList toArray() doesnt work well

Question

toArray() doesnt work as expected
any suggestion?
thx~
>
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.Integer;
     at util.ArrayUtil.main(ArrayUtil.java:22)
{quote}
package util;
import java.util.*;
public class ArrayUtil
{   public static <E> E[] merge(E[]... e)
    {     LinkedList<E> ll = new LinkedList();
     for(E[] e_temp : e)
     {   if(e_temp == null) continue;
         for(E e_temp2 : e_temp) if(e_temp2 != null) ll.add(e_temp2);
     return (E[])ll.toArray();
    public static void main(String[] args)
    {     Integer[] a1 = null;
     Integer[] a2 = null;
     Integer[] a3 = {1,2,3};
     Integer[] a4 = {4,5,6};
     Integer[] a = (Integer[])merge(a1, a2);                //ClassCastException is triggered
     System.out.println(a.length);
     for(int i=0; i<a.length; i++)
     System.out.println(a);

Answer 1

could you pls show me a sample?
public static <E> E[] merge(E[]... e)
    {     LinkedList<E> ll = new LinkedList<E>();
     for(E[] e_temp : e)
     {   if(e_temp == null) continue;
         for(E e_temp2 : e_temp) if(e_temp2 != null) ll.add(e_temp2);
     E[] out = (E[])Array.newInstance(e.getClass(), ll.size());
     return ll.toArray(out);
    }Exception in thread "main" java.lang.ClassCastException: [[[Ljava.lang.Integer; cannot be cast to [Ljava.lang.Integer;
     at util.ArrayUtil.main(ArrayUtil.java:23)
{quote}