实验指导书：实验7 异常处理与异常类

实验实验 7 异常处理与异常类异常处理与异常类 一一 实验目的及实验环境实验目的及实验环境 1 理解 Java 异常的基本概念和处理机制 2 掌握 Java 异常处理的方法 抛出和捕获异常 try throw throws catch 语句和 finally 的用法 3 理解异常类的作用 掌握创建异常类的方法 二二 实验内容实验内容 1 基本内容 实验前请及时熟悉如下相关内容 1 Java 的异常处理机制 2 异常类的应用 3 常见的异常 除数为零等 4 多异常处理 5 由方法抛出异常 6 必须要捕获的异常 2 综合实验 综合实验 2 1 Y Daniel Liang英文版第英文版第10版版P488 12 2 InputMismatchException Y Daniel Liang英文版八版英文版八版P456 13 2 NumberFormatException Write a program that prompts the user to read two integers and displays their sum Your program should prompt the user to read the number again if the input is incorrect 2 2 Y Daniel Liang英文版第英文版第10版版P488 12 3 Y Daniel Liang英文版八版英文版八版 P456 13 3 ArrayIndexOutBoundsException Write a program that meets the following requirements Create an array with 100 randomly chosen integers Prompt the user to enter the index of the array then display the corresponding element value If the specified index is out of bounds display the message Out of Bounds 2 3 Y Daniel Liang英文版第英文版第10版版P488 12 4 Y Daniel Liang英文版八版英文版八版 P456 13 4 IllegalArgumentException Modify the Loan class in Listing 10 2 to throw IllegalArgumentException if the loan amount interest rate or number of years is less than or equal to zero 2 4 Y Daniel Liang英文版第英文版第10版版P488 12 5 Y Daniel Liang英文版八版英文版八版 P456 13 5 IllegalTriangleException Exercise 11 1 defined the Triangle class with three sides In a triangle the sum of any two sides is greater than the other side The Triangle class must adhere to this rule Create the IllegalTriangleException class and modify the constructor of the Triangle class to throw an IllegalTriangleException object if a triangle is created with sides that violate the rule as follows Construct a triangle with the specified sides public Triangle double side1 double side2 double side3 throws IllegalTriangleException Implement it 三 程序清单及结果 三 程序清单及结果 1 package 异常处理 import java util Scanner public class text1 public static void main String args TODO Auto generated method stub int a b Scanner s new Scanner System in System out println read two integers while true try a s nextInt b s nextInt System out printf d a b catch Exception e System out println read the number again s nextLine 2 package 异常处理 import java util Scanner public class text2 public static void main String args TODO Auto generated method stub int sz new int 100 for int i 0 i sz length i sz i int Math random 100 System out println enter the index of the array Scanner s new Scanner System in int n s nextInt try System out println sz n catch ArrayIndexOutOfBoundsException e System out println System out println 3 import java lang Math import java io BufferedReader import java io InputStreamReader 自定义异常类 继承与异常类Exception class MyException extends Exception MyException String cause double m 若出现异常 每处理一次异常 标记flag shiyan3 flag 输出出错提示语句 System out println cause 的值为 m 小于等于零 class DaiKuan 定义变量贷款额 年利率 贷款年限 月还款额 总还款额 double DaiKuanE NianLiLv DaiKuanNianShu YueKuanHuanE ZongKuanHuanE public void DaiKuanJiSuan while shiyan3 flag 3 try 依次输入贷款额 年利率 贷款年限 BufferedReader br new BufferedReader new InputStreamReader System in System out println 请输入贷款额 System out println 请输入年利率 System out println 请输入贷款年限 DaiKuanE Double parseDouble br readLine NianLiLv Double parseDouble br readLine DaiKuanNianShu Double parseDouble br readLine catch Exception e try 若贷款额不大于零 抛出异常 if DaiKuanE 0 throw new MyException 贷款额 DaiKuanE catch MyException e try 若年利率不大于零 抛出异常 if NianLiLv 0 throw new MyException 年利率 NianLiLv catch MyException e try 若贷款年限不大于零 抛出异常 if DaiKuanNianShuside3 this side2 side2 this side3 side3 else throw new IlleagalTriangleException side1 side2 side3 public String tostring return 合法 心得 实验过程中try块中的语句块只要发生异常就立刻爆出异常对象 然后被 对应的catch块接住 也就是try之后的代码不会在程序中执行 当然也不会有任 何的作用 当catch记住对象后 会执行相应的catch之后的代码 而无论是否发 生异常fin