异常

/*

毕老师用电脑上课。

问题领域中涉及两个对象。

毕老师，电脑。

分析其中的问题。

比如电脑蓝屏啦。冒烟啦。

*/

class LanPingException extends Exception

{

LanPingException(String msg)

{

super(msg);

}

}

class MaoYanException extends Exception

{

MaoYanException(String msg)

{

super(msg);

}

}

class NoPlanException extends Exception

{

NoPlanException(String msg)

{

super(msg);

}

}

class Computer

{

private int state = 2;

public void run()throws LanPingException,MaoYanException

{

if(state==1)

throw new LanPingException("电脑蓝屏啦！！");

if(state==2)

throw new MaoYanException("电脑冒烟啦！！");

System.out.println("电脑运行");

}

public void reset()

{

state = 0;

System.out.println("电脑重启");

}

}

Lan异常

Computer类run方法告诉问题

Teacher类prelect预先给出处理方法（catch）

Mao异常

Teacher prelect中不能处理的异常，继续抛出，throw。Prelect标识

在exceptiontest catch 被抛出的异常，进行处理。

class Teacher

{

private String name;

private Computer comp;

Teacher(String name)

{

this.name = name;

comp = new Computer();

}

public void prelect()throws NoPlanException

{

try

{

comp.run();

System.out.println(name+"讲课");

}

catch (LanPingException e)

{

System.out.println(e.toString());

comp.reset();

prelect();

}

catch (MaoYanException e)

{

System.out.println(e.toString());

test();

//可以对电脑进行维修。

// throw e;

throw new NoPlanException("课时进度无法完成，原因："+e.getMessage());

}

}

public void test()

{

System.out.println("大家练习");

}

}

class ExceptionTest

{

public static void main(String[] args)

{

Teacher t = new Teacher("毕老师");

try

{

t.prelect();

}

catch (NoPlanException e)

{

System.out.println(e.toString()+"......");

System.out.println("换人");

}

}

}

/*

class NoAddException extends Exception

{}

void addData(Data d)throws NoAddException

{

连接数据库

try

{

添加数据。出现异常 SQLException();

}

catch(SQLException e)

{

//处理代码。

throw new NoAddException();

}

fianlly

{

关闭数据库。

}

}

*/