What are the differences between recursion and iteration in Java?

The Recursion and Iteration both repeatedly execute the set of instructions. Recursion is when a statement in a function calls itself repeatedly. The iteration is when a loop repeatedly executes until the controlling condition becomes false. The primary difference between recursion and iteration is that recursion is a process, always applied to a function and iteration is applied to the set of instructions which we want to get repeatedly executed.

Recursion

• Recursion uses selection structure.
• Infinite recursion occurs if the recursion step does not reduce the problem in a manner that converges on some condition (base case) and Infinite recursion can crash the system.
• Recursion terminates when a base case is recognized.
• Recursion is usually slower than iteration due to the overhead of maintaining the stack.
• Recursion uses more memory than iteration.
• Recursion makes the code smaller.

Example

Live Demo

public class RecursionExample {
   public static void main(String args[]) {
      RecursionExample re = new RecursionExample();
      int result = re.factorial(4);
      System.out.println("Result:" + result);
   }
   public int factorial(int n) {
      if (n==0) {
         return 1;
      }
      else {
         return n*factorial(n-1);
      }
   }
}

Output

Result:24

Iteration

• Iteration uses repetition structure.
• An infinite loop occurs with iteration if the loop condition test never becomes false and Infinite looping uses CPU cycles repeatedly.
• An iteration terminates when the loop condition fails.
• An iteration does not use the stack so it's faster than recursion.
• Iteration consumes less memory.
• Iteration makes the code longer.

Example

Live Demo

public class IterationExample {
   public static void main(String args[]) {
      for(int i = 1; i <= 5; i++) {
         System.out.println(i + " ");
      }
   }
}

Output

1
2
3
4
5