Program to find HCF of two numbers by iterative approach:                                                     

package quipoin.javaeasyprograms;
public class HCF {

	static int findHcf(int x, int y) {
		int n = Math.min(x, y);
		for (int i = n; i >= 1; i--) {
			if (x % i == 0 && y % i == 0) {
				return i;
			}
		}
		return 0;
	}

	public static void main(String[] args) {
		System.out.println(findHcf(27, 18));
		System.out.println(findHcf(5, 18));
	}
}

Output:

9
1

Program to find HCF of two numbers by recursive approach:

package quipoin.javaeasyprograms;
public class HCF {
    static int findHcf(int x, int y) {
        if(x==0)
            return y;
        else
            return findHcf(y%x,x);
    }
    public static void main(String[] args) {
        System.out.println(findHcf(18, 24));
        System.out.println(findHcf(5, 18));
    }
}

Output:

72
1