(1) 乘客可以免费托运重量不超过30kg（含30kg）的行李。
(2) 假设行李超过30kg，其收费标准为：

• 头等舱国内乘客，超重部分每千克收费4元。
• 其他舱国内乘客，超重部分每千克收费6元。
• 外国乘客：超重部分每千克比国内乘客多1倍。
• 残疾乘客：为正常价格的半价。

(3) 行李重量超出部分，不满1kg的按照1kg计算。

代码实现如下：

1、main方法：

package Ticket;public class Test {public static void main(String[] args) {ICalcTicket ct = new CalcTicketImpl();ct.CalcTicket();}
}

2、接口（ ICalcTicket.java ）：

package Ticket;public interface ICalcTicket {void CalcTicket();int levelselect(int x, int y, int level, int moreweight);int TotalMoney(double weight, int nation, int health, int level);int IsTrue(int flag);}

3、接口实现类（ CalcTicketImpl.java ）：

package Ticket;import java.util.Scanner;import static java.lang.Math.ceil;public class CalcTicketImpl implements ICalcTicket {private int flag = 0;private int money = 0;private double weight;private int moreweight;Scanner scanner = null;int[] a = new int[3];FormatJudge fj = new FormatJudge();public void CalcTicket() {while (true) {scanner = new Scanner(System.in);System.out.println("Please enter weight in KG (with two decimal places):");try {weight = scanner.nextDouble();break;} catch (Exception e) {System.out.println("输入信息不符合要求，请重新输入！");}}if (weight < 30) {System.out.println("Your luggage will be free to carry!");} else {//调用IsTrue方法输入国籍，健康状况，舱位等级，并将返回值存入数组，作为调用TotalMoney时传入的三个参数for (flag = 0; flag <= 2; flag++) {int input = IsTrue(flag);a[flag] = input;}money = TotalMoney(weight, a[0], a[1], a[2]);System.out.println("You should pay ¥ " + money + " .");}}//舱位等级判断public int LevelSelect(int x, int y, int level, int moreWeight) {switch (level) {case 1:  //first classmoney = moreWeight * x;break;case 2:  //other classesmoney = moreWeight * y;break;default:break;}return money;}//计算运费public int TotalMoney(double weight, int nation, int health, int level) {moreweight = (int) ceil(weight - 30);if (nation == 1) {    //domesticif (health == 1) {    //disabledmoney = LevelSelect(2, 3, level, moreweight);} else {    //healthymoney = LevelSelect(4, 6, level, moreweight);}} else {  //foreignerif (health == 1) {  //disabledmoney = LevelSelect(4, 6, level, moreweight);} else {  //healthymoney = LevelSelect(8, 12, level, moreweight);}}return money;}//输入国籍，健康状况，舱位等级三个参数并捕捉输入异常public int IsTrue(int flag) {int input;this.flag = flag;while (true) {scanner = new Scanner(System.in);if (flag == 0) {System.out.println("Please enter '1' or '2' (1:domestic, 2:foreigner):");} else if (flag == 1) {System.out.println("Please enter '1' or '2' (1:disabled, 2:healthy):");} else if (flag == 2) {System.out.println("Please enter '1' or '2' (1:first class, 2:other classes):");}//捕捉两个异常，一个是scanner.nextInt异常，一个是自定义异常try {input = scanner.nextInt();fj.judge(input);break;} catch (Exception e) {System.out.println("输入信息不符合要求，请重新输入！");}}return input;}
}

4、自定义异常类（ FormatException.java ）：

package Ticket;//自定义异常
public class FormatException extends Exception {public FormatException() {super();}
}//将输入的值是int类型但不是1或2的异常抛出
class FormatJudge {public void judge(int m) throws FormatException {if (m != 1 && m != 2) {throw new FormatException();}}
}