上题目：

python 版本：

from curses.ascii import isdigitfrom pandas import interval_rangeimport redef Is_numerical(str1):    return  re.match('^\d*.?\d*',str1) != Nonedef Get_input():    principalstr = input("Enter the principal: ")    while principalstr.isdigit() == False:        print("Please input the numerical info: ")        principalstr = input("Enter the principal: ")    intereststr = input("Enter the rate of interest: ")    while Is_numerical(intereststr) == False:        print("Please input the numerical info: ")        intereststr = input("Enter the rate of interest: ")    yearsstr = input("Enter the number of years: ")    while yearsstr.isdigit() == False:        print("Please input the numerical info: ")        yearsstr = input("Enter the number of years: ")    return float(principalstr),float(intereststr),float(yearsstr)def CalculateSimpleIntrest(principal,interest,years): #如果是Java，里面必须宣称类型，python不用    amount = principal*(1+interest*years/100)    return amountdef Display(years,interest,amount):    print("After {0} years at {1}%, the investment will \n be worth ${2}".format(years,interest,amount))principal,interest,years = Get_input()amount = CalculateSimpleIntrest(principal,interest,years)Display(years,interest,amount)

效果

java版本：

import java.util.Scanner;public class CalSimInterest{private float principal;private float interest;private float years;private float amount;public void Getinput(){System.out.println("Enter the principal: ");Scanner sc = new Scanner(System.in );String principalstr = sc.next();while (this.isNumeric(principalstr) == false)    {        System.out.println("Enter the principal: ");        principalstr = sc.next();    }    System.out.println("Enter the rate of interest: ");    String intereststr = sc.next();    System.out.println("Enter the number of years: ");    String yearsstr = sc.next();    this.principal = Float.parseFloat(principalstr);    this.interest = Float.parseFloat(intereststr);    this.years = Float.parseFloat(yearsstr);    sc.close();}float calculateSimpleInterest(){System.out.println(this.principal + " " + this.interest + " " + this.years);float result = this.principal * (1 + this.interest * this.years / 100);System.out.println(result);this.amount = result;return result;}public void display(){calculateSimpleInterest();System.out.println(    "After " + this.years + " years at " + this.interest + "%, the investment will \n be worth $" + this.amount);}private boolean isNumeric(String secondstring) {return secondstring != null & & secondstring.matches("-?\\d+(\\.\\d+)?");}public static void main(String[] args){CalSimInterest lesson12 = new CalSimInterest();lesson12.Getinput();lesson12.display();}}

效果：