对于一些代码，可能会希望无论try块中的异常是否抛出，它们都能得到执行。这通常适用于内存回收之外的情况。为了达到这样的效果，可以在异常处理程序后面加上finally子句。如下：
1 try{ 2 3 //The guarded region: Dangerous activities 4 5 //taht might throw A,B, or C 6 7 }catch(A a1){ 8 9 //handler for situation A 10 11 }catch(B b1){ 12 13 //Handler for situation B 14 15 }catch(C c1){ 16 17 //Handler for situtation C 18 19 }finally{ 20 21 //activities that happen every time 22 23 }
为了证明finally总能运行，可以试试如下程序：
1 package com.exceptions; 2 3 class ThreeException extends Exception{} 4 public class FinallyWorks { 5 static int count = 0; 6 public static void main(String[] args){ 7 while(true){ 8 try{ 9 if(count++ ==0) 10 throw new ThreeException(); 11 System.out.println("No Exception"); 12 }catch(ThreeException e){ 13 System.out.println("ThreeException"); 14 }finally{ 15 System.out.println("In finally clause"); 16 if(count == 2) break; 17 } 18 } 19 } 20 }
结果如下：
1 ThreeException 2 In finally clause 3 No Exception 4 In finally clause