递归方法

public class DigitPrint {
    public static void printDigit(int num){
        if(num<9){
            System.out.println(num);
        }
        else{
            printDigit(num/10);
            System.out.println(num%10);

        }
    }
    public static void main(String[] args) {
        printDigit(1234);
    }
}