挑战编程技能之第一章练习

小费计算程序

因为觉得java的GUI不是主流，就没有实现GUI交互。
下面是代码：
import java.util.*;
public class CountTip {

public static void main(String[] args) {
// TODO Auto-generated method stub
Tip tip = new Tip();
System.out.print("请输入金额：");
Scanner scanner = new Scanner(System.in);
do {
double total = scanner.nextDouble();
if (total > 0) {
tip.setTotal(total);
break;
}else {
System.out.println("输入不能是负值，请重新输入");
}

}while(true);
System.out.print("请输入小费比例：");
do {
double percentOfTip= scanner.nextDouble();
if (percentOfTip > 0) {
percentOfTip = percentOfTip / 100;
tip.setPercentOfTip(percentOfTip);
break;
}else {
System.out.println("输入不能是负值，请重新输入");
}

}while(true);
scanner.close();
System.out.println("小费是：" + tip.countTip());
System.out.println("总金额是：" + tip.getTotalAndTip());
}

}
小费数据计算类
class Tip {
private double total;
private double percentOfTip;

public double getTotal() {
return total;
}

public void setTotal(double total) {
this.total = total;
}

public double getPercentOfTip() {
return percentOfTip;
}

public void setPercentOfTip(double percentOfTip) {
this.percentOfTip = percentOfTip;
}

//四舍五入保留小数点后两位
public double point_two(double value) {
value *= 100;
double beforePoint = (int) value;//浮点数到整数的转换是通过舍弃小数得到，而不是四舍五入
double afterPoint = value - beforePoint;
if (afterPoint > 0.5) {
return (beforePoint + 1) / 100;
}
return beforePoint / 100;

}
//计算小费
public double countTip() {
double tip = total * percentOfTip;
return point_two(tip);
}

//得到小费加金额
public double getTotalAndTip() {
double totalAndTip = total + countTip();
return totalAndTip;
}

}