阅读以下代码,写出程序运行的结果:
public class CatchWho { public static void main(String[] args) { try { try { throw new ArrayIndexOutOfBoundsException(); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch"); } throw new ArithmeticException(); } catch(ArithmeticException e) { System.out.println("发生ArithmeticException"); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch"); } } }
运行结果:
那么接下来的代码会发生什么呢?
public class CatchWho2 { public static void main(String[] args) { try { try { throw new ArrayIndexOutOfBoundsException(); } catch(ArithmeticException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch"); } throw new ArithmeticException(); } catch(ArithmeticException e) { System.out.println("发生ArithmeticException"); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch"); } } }
运行结果如下:
阅读EmbedFinally.java实例,在阅读它,观察其输出并进行总结。
public class EmbedFinally { public static void main(String[] args) { int result; try { System.out.println("in Level 1"); try { System.out.println("in Level 2"); //result=100/0; //Level 2 try { System.out.println("in Level 3"); result=100/0; //Level 3 }catch (Exception e){ System.out.println("Level 3:" + e.getClass().toString()); } finally{ System.out.println("In Level 3 finally"); } // result=100/0; //Level 2 }catch (Exception e) { System.out.println("Level 2:" + e.getClass().toString()); }finally{ System.out.println("In Level 2 finally"); } // result = 100 / 0; //level 1 }catch (Exception e){ System.out.println("Level 1:" + e.getClass().toString()); }finally { System.out.println("In Level 1 finally"); } } }
当有多层嵌套的finally时,异常在不同层次抛出,在不同的位置抛出,可能会导致不同的finally语句块执行顺序。
finally语句块一定会执行吗?
public class SystemExitAndFinally { public static void main(String[] args) { try { System.out.println("in main"); throw new Exception("Exception is thrown in main"); //System.exit(0); } catch(Exception e) { System.out.println(e.getMessage()); System.exit(0); } finally { System.out.println("in finally"); } } }
在运行结果中可以看出finally语句并没有执行。