2.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1

//Bank类
package d0923;

public class Bank {
private double balance;

Bank(double a) {
	balance += a;
}

void withDrawal(double dAmount) throws InsufficientFundsException, NagativeFundsException  {
	if(dAmount<0)		
		throw new InsufficientFundsException(dAmount);
	if(dAmount>balance)
		throw new NagativeFundsException();
	System.out.println("取款："+dAmount);
	this.balance-=dAmount;
}

}

///InsufficientFundsException
package d0923;

public class InsufficientFundsException extends Exception {
InsufficientFundsException(double i)
{
System.out.println("发生错误："+"取款额"+i+"为负数。");
}
}

///NagativeFundsException
package d0923;

public class NagativeFundsException extends Exception {
NagativeFundsException()
{
System.out.println("超出余额：");
}
}

package d0923;

public class NagativeFundsException extends Exception {
NagativeFundsException()
{
System.out.println("超出余额：");
}
}

//测试主类

package d0923;

public class TestBank {

public static void main(String[] args)  {
	Bank b=new Bank(100);
	try{
		b.withDrawal(-15);
	}
	catch(InsufficientFundsException e)
	{
		e.printStackTrace();
	}
	catch(NagativeFundsException e)
	{
		e.printStackTrace();
	}
	
	try{
		b.withDrawal(150);
	}
	catch(InsufficientFundsException | NagativeFundsException e)
	{
		e.printStackTrace();
	}


}

}
//运行结果

发生错误：取款额-15.0为负数。 ///withdrawal调用的构造函数
d0923.InsufficientFundsException
at d0923.Bank.withDrawal(Bank.java:12) /// printStack
at d0923.TestBank.main(TestBank.java:8)
超出余额：
d0923.NagativeFundsException
at d0923.Bank.withDrawal(Bank.java:14)
at d0923.TestBank.main(TestBank.java:20)