java异常处理：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),

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 extends Exception{

    static double balance=0;
    Bank(double r)
    {
        balance+=r;
    }
        void withDrawal(double dAmount) throws  InsufficientFundsException,NagativeFundsException{
        if(dAmount > balance) throw new InsufficientFundsException("取款余额不足");
        else  if(dAmount<0) throw new NagativeFundsException("取款为负数");
        else       System.out.print("银行里还剩余："+(balance-dAmount));
    }

}

package exception;

public class InsufficientFundsException extends Exception {

    String s1;
    InsufficientFundsException(String t)
    {   s1=t;  }
    public String getMassage1()
    {    return s1;   }

} 

package exception;

public class NagativeFundsException extends Exception {

    String s;
    NagativeFundsException(String t)
    {   s=t;  }
    public String getMassage()
    {    return s;   }

}