求一个整数的因数分解--Java--小白必懂

public class OJ_1415 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int sNum = num;
        splitNum(sNum);
    }
 
    // 求整数的因式分解的方法
    public static void splitNum(int num) {
        if (num == 1) {
            System.out.println(num);
        }
        HashMap<Integer, Integer> hap = new HashMap<>();
        int kNum = num;
        for (int i = 2; i <= kNum; ) {
            if (kNum % i == 0) {
                if (hap.keySet().contains(i)) {
                    hap.put(i, hap.get(i) + 1);
                } else {
                    hap.put(i, 1);
                }
                kNum = kNum / i;
                i=2;
            } else {
                i++;
            }
        }
        // map中保存了每个因子的出现次数，然后遍历这个hashMap,如果需要从小到大显示还需要排序
        // 使用Collections的sort方法对hashMap的key进行排序
        Collection<Integer> key = hap.keySet();
        List<Integer> lst = new ArrayList<>(key);
        Collections.sort(lst);
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < lst.size(); i++) {
            sb.append(""+lst.get(i) + "^" + "("+hap.get(lst.get(i))+")");
        }
        sb.append("=" + num);
        System.out.println(sb.toString());
    }
}