实验3(10)异常——必做.doc

班级： 姓名： 学号： 成绩 异常实验目的：1 理解异常现象及异常的抛出机制2 掌握异常抛出时的处理机制3 掌握自定义异常的方法4 能够掌握在方法代码中添加抛出异常的处理实验要求和过程1. public class TestApp public static void main(String args) try int i = 0; int j = 1 / i; String myname=null; if(myname.length()2) System.out.print(“1”); catch(NullPointerException e) System.out.print(“2”); catch(Exception e) System.out.print(“3”); 分析上述程序运行后的输出的结果和原因。输出结果是：3原因：int j = 1 / i；这句话除0异常，catch并没有相对应Exception e子类捕获错误，所以输出Exception中语句，并结果程序。2. 下面是一个名称为NegativeAmountException的自定义异常类，表示一个不正常的银行账目事件类。填充下面的语句，完成该类的编写。class NegativeAmountException _extends_ _Expection_/NegativeAmountException异常：用消息s创建异常NegativeAmountException(String s)super(s);class Accountdouble balance;/构造函数，余额为0；public Account()balance = 0;/构造函数，余额为n，如果初始余额小于0抛出异常public Account( double n) throws NegativeAmountExceptionif(n0)this.balance = n;else _throw new_NegativeAmountException(“余额小于0异常”);/查询余额方法，返回当前余额public double getBalance()return this.balance;/存款方法，存款数额amount; 如果存款数目小于0抛出异常public void deposit(double amount)_ throws NegativeAmountException _if(amount=0)balance+=amount;else throw new NegativeAmountException(存款金额小于0异常！);/取款方法，取款数额amount; 如果取款数目小于0抛出异常public void withdraw(double amount)_ throws NegativeAmountException if(amount0)throw new NegativeAmountException(取款金额小于0异常！);else if(balanceamount)throw new NegativeAmountException(取款金额大于余额异常！);elsebalance-=amount; /测试类如下：public class TestNegativeAmountExceptionpublic static void main(String args) try Account a1 = new Account();a1.deposit(100);/a1.withdraw(-100);a1.withdraw(30);System.out.println(balance of a1: + a1.getBalance();/Account a2 = new Account(-10);/a2 = new Account(10);/a2.deposit(-20);/a2.withdraw(-10);/a2.withdraw(30);/a2.withdraw(3);/System.out.println(balance of a1: + a2.getBalance(); catch (NegativeAmountException e) e.printStackTrace();3. 模仿上题中NegativeAmountException自定义异常的写法，根据下面要求写程序。1) 自定义异常OnlyOneException与NoOprandException，并补充各自类的构造函数，参数用于保存异常发生时候的信息；2) 添加main方法，如果没有输入命令行参数 ，抛出NoOprandException异常并退出程序的执行；如果命令行参数的数目只要一个，抛出OnlyOneException异常并退出程序的执行；否则从命令行读入两个数据，计算这两个数据的和并输出。package shiyan10;public class NoOprandException extends Exception public NoOprandException(String args)System.out.println(没有参数); package shiyan10;public class OnlyOneException extends Exceptionpublic OnlyOneException(String s) System.out.println(只有一个参数); package shiyan10;public class TestNegativeAmountExceptionpublic static void main(String args)int sum=0;try if(args.length=0)throw new NoOprandException(args);else if(args.length=1)throw new OnlyOneException(args);elsefor(int i=0; i 0) this.balance = n; else throw new NegativeAmountException(余额小于0异常);/ 查询余额方法，返回当前余额public double getBalance() throws BlockedExceptionif(satstus=blocked) throw new BlockedException(冻结);else return this.balance;/ 存款方法，存款数额amount; 如果存款数目小于0抛出异常public void deposit(double amount) throws NegativeAmountException,BlockedExceptionif(satstus=blocked) throw new BlockedException(冻结);else if (amount = 0) balance += amount; else throw new NegativeAmountException(存款金额小于0异常！);/ 取款方法，取款数额amount; 如果取款数目小于0抛出异常public void withdraw(double amount) throws NegativeAmountException,BlockedExceptionif(satstus=blocked) throw new BlockedException(冻结);else if (amount 0) throw new NegativeAmountException(取款金额小于0异常！); else if (balance amount) throw new NegativeAmountException(取款金额大于余额异常！); else balance -= amount;package shiyan10;public class TestNegativeAmountException public static void main(String args)try Account a1 = new Account();a1.setSatstus(反对);a1.deposit(100);a1.setSatstus(blocked);/a1.withdraw(-100);a1.withdraw(30);System.out.println(balance of a1: + a1.getBalance();/Account a2 = new Account(-10);/a2 = new Account(10);/a2.deposit(-20);/a2.withdraw(-10);/a2.withdraw(30);/a2.withdraw(3);