java-异常-异常应用

  1 package p1.exception;
  2
  3
  4 /*
  5  * 老师用电脑上课。
  6  *
  7  * 问题领域中涉及两个对象。
  8  * 老师，电脑。
  9  *
 10  * 分析其中的问题。
 11  * 比如电脑蓝屏。冒烟。
 12  *
 13  */
 14
 15 class LanPingException extends Exception{
 16     public LanPingException(String msg) {
 17         super(msg);
 18         // TODO Auto-generated constructor stub
 19     }
 20 }
 21 class MaoYanException extends Exception{
 22     public MaoYanException(String msg) {
 23         super(msg);
 24         // TODO Auto-generated constructor stub
 25     }
 26 }
 27 class NoPlanException extends Exception{
 28     public NoPlanException(String msg) {
 29         super(msg);
 30         // TODO Auto-generated constructor stub
 31     }
 32 }
 33 class Computer{
 34     private int state = 2;
 35
 36     public void run() throws LanPingException,MaoYanException{
 37         if (state == 1) {
 38             throw new LanPingException("电脑蓝屏");
 39         }
 40         if (state == 2) {
 41             throw new MaoYanException("电脑冒烟");
 42         }
 43         System.out.println("电脑运行");
 44     }
 45     public void reset() {
 46         state = 0;
 47         System.out.println("电脑重启");
 48     }
 49 }
 50 class Teacher{
 51     private String name;
 52     private Computer comp;
 53     public Teacher(String name) {
 54         this.name = name;
 55         comp = new Computer();
 56         // TODO Auto-generated constructor stub
 57     }
 58     public void prelect() throws NoPlanException{
 59         try {
 60             comp.run();
 61             System.out.println(name+"讲课");
 62         } catch (LanPingException e) {
 63             System.out.println(e.toString());
 64             comp.reset();
 65             prelect();
 66
 67         } catch (MaoYanException e) {
 68
 69             System.out.println(e.toString());
 70             test();
 71             //可以对电脑进行维修，
 72 //            throw e;//做练习但没有解决冒烟问题抛出给别人
 73             throw new NoPlanException("课时进度无法完成，原因："+e.getMessage());
 74
 75         }
 76
 77
 78     }
 79     public void test() {
 80         System.out.println("大家练习");
 81     }
 82 }
 83 public class ExceptionTest {
 84
 85     public static void main(String[] args) {
 86         // TODO Auto-generated method stub
 87         Teacher t = new Teacher("武老师");
 88         try {
 89             t.prelect();
 90         } catch (NoPlanException e) {
 91             System.out.println(e.toString()+"......");
 92             System.out.println("换人");
 93         }
 94
 95     }
 96
 97 }
 98
 99 /*
100  * class NoAddException extends Exception{
101  *
102  * }
103  *
104  *
105  * void addData(Data d) throws NoAddException{
106  *
107  *         连接数据库
108  *         try{
109  *             添加数据。出现异常 SQLException();
110  *         }catche (SQLException e) {
111  *             //处理代码
112  *
113  *             thorw new NoAddException();     内部处理了异常对外进行异常的转换，也叫异常的封装
114  *                                             不该暴露出的问题就不暴露，你暴露了对方也不能处理
115  *
116  *         }finally{
117  *             关闭数据库
118  *         }
119  *
120  *
121  *
122  *
123  */
124  * }

ExceptionTest