public class Demo1
{
    public static void main(String[] args)
    {
        double[] myList = {34, 15, 66, 7};

        double[] myListCopy = new double[ 2*myList.length ]; // Create new array

        for ( int i = 0; i < myList.length; i++ ) // Copy old array elems
            myListCopy[i] = myList[i];
          
        myList = myListCopy;			  // Point to new array
    }
}