How to go through a collection without using any loop construct?

Question

Question about java interview. Is there any way in java programming, moreover, it constructs a loop to iterate over a given collection (Array) and works on each element of the collection.

Answer 1

Recursion is one way to do this.

void it(Iterator i) { if (i.hasNext()) { System.out.println(i.next()); it(i); } } 

Answer 2

In addition to recursion, there are utilities in the collection that you can use to create material in the collection. Note that this api also uses internal loop constructs. But the client code will look like this:

 CollectionUtils.forAllDo( yourCollection, new Closure() { void execute(java.lang.Object element) { // do smt with element } } ); 

Check here CollectionUtils: http://commons.apache.org/collections/apidocs/org/apache/commons/collections/Closure.html

Answer 3

Recursion ?

Answer 4

Yes, you can recursively go through a function to get the same functionality:

 public void iterate(int[] array, int index){ if (index >= array.length){ return; }else{ //work with element at array[index] iterate(array, index+1); } } 

Answer 5

You can change the iterative solution to recursive. Loops are iterative, so just create a recursive solution.

Answer 6

Using recursion, we iterate over an array or collection without using a loop. See below recursion method:

 public static void iterateArray(int nums[], int index) { if (nums.length == index) { return; } System.out.print(nums[index] + " "); iterateArray(nums, index + 1); }