编辑代码

public class Prog4 {
    public static void main(String[] args) {
        int n = 13;

        decompose(n);
    }

    private static void decompose(int n) {
        System.out.print(n + "=");

        for (int i = 2; i < (n + 1); i++) {
            //while用于未知循环数，以目标为导向
            while (((n % i) == 0) && (n != i)) {
                n /= i;

                System.out.print(i + "*");
            }

            if (n == i) {
                System.out.println(i);

                break;
            }
        }
    }
}