Authors:
Stuart Reges, Marty Stepp
Chapter:
Arraylists
Exercise:
Exercises
Question:16 | ISBN:9780136091813 | Edition: 2
Question
Write a method called interleave that accepts two ArrayList s of integers a1 and a2 as parameters and inserts the elements of a2 into a1 at alternating indexes. If the lists are of unequal length, the remaining elements of the longer list are left at the end of a1. For example, if a1 stores [10, 20, 30] and a2 stores [4, 5, 6, 7, 8] , the call of interleave(a1, a2); should change a1 to store [10, 4, 20, 5, 30, 6, 7, 8] . If a1 had stored [10, 20, 30, 40, 50] and a2 had stored [6, 7, 8] , the call of interleave(a1, a2); would change a1 to store [10, 6, 20, 7, 30, 8, 40, 50] .
Answer
Implementation of interleave method:
public static void interleave(ArrayList intList1,
ArrayList intList2)
{
int i = 1; // for intList1
int j = 0; // for intList2
while(j < intList2.size())
{
if(i < intList1.size())
{
intList1.add(i, intList2.get(j));
i += 2;
}
else
{
intList1.add(intList2.get(j));
i++;
}
j++;
}
}