复利程序更新-单元测试

　　在写单元测试前，首先进行复利程序代码的在结构上的修改，将显示与计算分隔开，目的是为了便于传入参数进行测试，并且重命名类的名字方便理解。

package ch1;

import java.util.InputMismatchException;
import java.util.Scanner;

public class calculator {

public static void main(String[] args) {
System.out.print("请选择求单利1,复利2,本金3,时间4,利率5,投资6,贷款月还款计算7,退出8");
Scanner scanner = new Scanner(System.in);
int a=0;
try{
a = Math.abs(scanner.nextInt());}
catch(InputMismatchException e){
main(null);
}
input(a);
scanner.close();
}

static void input(int a) {
Scanner scanner = new Scanner(System.in);
int k = a;
String fruit=null;
try {
switch (a) {
case 1: {
System.out.print("请输入本金");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入年利率");
double rate = Math.abs(scanner.nextDouble());
System.out.print("请输入存入年限");
double C = Math.abs(scanner.nextInt());
double fruit1=simple_interest(A, rate, C);
System.out.println("单利终值" + fruit1);
main(null);

}
break;
case 2: {
System.out.print("请输入本金");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入年利率");
double B = Math.abs(scanner.nextDouble());
System.out.print("请输入存入年限");
int C = Math.abs(scanner.nextInt());
fruit=compound_interest(A, B, C);
System.out.println("复利终值" + fruit);
main(null);
}
break;
case 3: {
System.out.print("请输入预期钱数");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入年利率");
double rate = Math.abs(scanner.nextDouble());
System.out.print("请输入存入年限");
double C = Math.abs(scanner.nextInt());
fruit=capital(A, rate, C);
System.out.println("本金" + fruit);
main(null);
}
break;
case 4: {
int i=0;
System.out.print("请输入本金");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入年利率");
double B = Math.abs(scanner.nextDouble());
System.out.print("请输入预期金额");
double C = Math.abs(scanner.nextDouble());
i=time(A, B, C);
System.out.println("需" + i + "年");
main(null);
}
break;
case 5: {
System.out.print("请输入本金");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入预期金额");
double B = Math.abs(scanner.nextDouble());
System.out.print("请输入存入年限");
double C = Math.abs(scanner.nextDouble());
fruit=rate(A, B, C);
System.out.println("利率为" + fruit);
main(null);
}
break;
case 6: {
System.out.print("请输入投资额");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入年利率");
double B = Math.abs(scanner.nextDouble());
System.out.print("请输入存入年限");
int C = Math.abs(scanner.nextInt());
fruit=invest(A, B, C);
System.out.println("最终获利" + fruit);
main(null);
}
break;
case 7: {
System.out.print("请输入贷款额");
double A = Math.abs(scanner.nextDouble());
System.out.print("请输入贷款利率");
double B = Math.abs(scanner.nextDouble());
System.out.print("请输入贷款年限");
int C = Math.abs(scanner.nextInt());
fruit=repayment(A, B, C);
//main(null);

}
break;
case 8:scanner.close();
break;
default:
System.out.print("请重新输入");
}
} catch (InputMismatchException e) {
input(k);
}
}

static double simple_interest(double a, double rate, double c) {
double A = a;
double D = 1;
double C = c;
D = A * rate * C;
return A+D;
}
static String compound_interest(double a2, double b2, int c2) {
double A = a2;
double B = b2;
int C = c2;
double D = 1;
for (int i = 1; i <= C; i++) {
D = D * (1 + B);
}
return String.format("%.4f", A*D);
}
static String capital(double a2, double rate2, double c2) {
// TODO Auto-generated method stub
double A = a2;
double rate = rate2;
double C = c2;
double D = 1;
for (int i = 1; i <= C; i++) {
D = D * (1 + rate);
}

return String.format("%.4f", A/D);
}
static int time(double a2, double b2, double c2) {
double A = a2;
double B = b2;
double C = c2;
double D = 1;
double E = 1;
int i = 1;

while (true) {
D = D * (1 + B);
E = A * D;
if (E <= C)
i++;
else
break;
}
return i;
}

static String rate(double a2, double b2, double c2) {
double A = a2;
double B = b2;
double C = c2;
double D = 1;
D = Math.pow(B / A, 1 / C) - 1;
return String.format("%.4f", D);
}

static String invest(double a2, double b2, int c2) {
// TODO Auto-generated method stub
double A = a2;
double B = b2;
int C = c2;
double D = 0;
for (int i = 1; i <= C; i++) {
D = D + A;
D = D * (1 + B);
}
return String.format("%.4f", D);
}

static String repayment(double a2, double b2, int c2) {
// TODO 自动生成的方法存根
double A = a2;
double B = b2;
int C = c2;
double D = 0;
for (int i = 1; i <= C; i++) {
D = A * Math.pow(1.0 + B, C);
}
double Repayment = D / (C * 12);
double interest = A * B * C;
double sum = A + interest;
double Repayment1 = sum / (C * 12);
System.out.println("每月需要还款(单利)" + Repayment1);
System.out.println("每月需要还款(复利)" + String.format("%.4f", Repayment));
return String.format("%.4f", Repayment);
}

}

　　在单元测试中，共分两个场景。

1.给定数值给函数，判断结果是否与预期一致。如下图



2.进行输入异常判断，由于还不了解如何对用户输入进行自动测试，因此通过手动输入字符空格等进行测试。



所有代码都已上传至https://github.com/zhengmingze/java.git

文件名分别为：calculator.java ,calculatorTest.java