07exception课件.ppt

第7课 异常;提问;学习目标;本课内容;异常什么时候发生;异常是什么;常见异常;常见异常;常见异常;常见异常;程序Test运行结果：java Test lisa bily kessy Exception in thread main java.lang.ArrayIndexOutOfBoundsException:3 at Test.main(Test.java:13);每种异常都是使用一个java类表示 每个具体的异常都是使用对应的java类的实例来表示 程序发生了一个异常，通常称程序抛出一个异常。这里所谓抛出异常，就是产生一个对于异常类的实例。;2. Java异常分类;异常类层次;已检查异常(Check Exception)和未检查异常(unCheck Exception）;3. 异常处理机制(★)把异常捉住;捉住处理异常;;4. 捕获异常多种异常，一并处理;捕获异常;捕获异常; Common com=null; try { com = (Common) Class.forName(generclass.lession6.Plane).newInstance(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); //throw e.fillInStackTrace(); } catch(Exception e) { e.printStackTrace(); } finally{ System.out.println(finally over); } System.out.println(ssss);;5. 声明抛弃异常throw 和throws;创建用户自定义异常类;class MyException extends Exception { public MyException() {} public MyException(String msg) { super(msg); } } class Devide{ public int division(int x,int y) throws MyException { if(y==0){ throw new MyException(被零除了); } return x/y; } public int division1(int x,int y) { int a=0; try{ a = x/y; } catch(Exception e){ e.printStackTrace(); } return a; } };public class DevideException { public static void main(String[] args){ Devide d = new Devide(); try { d.division(10,0); System.out.println(hello1); } catch (MyException e) { //System.out.println(e.getMessage()); e.printStackTrace(); } finally{ System.out.println(hello); } System.out.println(hello1); System.out.println(hello); } };嵌套异常处理;class MyException1 extends Exception { } class MyException2 extends Exception