建立exception包，建立Bank类，类中有变量double balance表示存款,Bank类的构造方法能增加存款，Bank类中有取款的发方法withDrawal(double dAmount),当取款的数额大于存款时,抛出InsufficientFundsException,取款数额为负数，抛出NagativeFundsException,如new Bank(100),表示存入银行100元，当用方法withdrawal(150)，withdrawal(-15)时会抛出自定义异常。
package exception;public class Bank {double balance;public Bank(double balance){}public void withDrawal(double dAmount) throws Exception{if(dAmount>balance){throw new InsufficientFundsException();}if(dAmount<0){throw new NagativeFundsException();}balance =balance-dAmount;}}
package exception;public class InsufficientFundsException extends Exception {@Overridepublic String getMessage() {// TODO 自动生成的方法存根return "余额不足！";}}
package exception;public class NagativeFundsException extends Exception {@Overridepublic String getMessage() {// TODO 自动生成的方法存根return "取款数不能为负数";}}
package exception;public class Test1 {public static void main(String[] args) {// TODO 自动生成的方法存根 Bank b=new Bank(100);try{ b.withDrawal(150);}catch (Exception e){System.out.println(e.getMessage());}try{b.withDrawal(-15);}catch(Exception e){System.out.println(e.getMessage()) ;}}}
;)
