try和finally return返回值顺序,finally关闭多个资源

一 . 问题

1. 错误代码

    private static int testCatchError() {
        int resultInt = 0;

        try {
            resultInt = 777;
            System.out.println(resultInt);
            return resultInt;
        } catch (Exception e) {
            resultInt = 7;
            System.out.println("error:" + resultInt);
            return resultInt;
        } finally {
            try {
                resultInt = 888;
                System.out.println("finally1:" + resultInt);

                resultInt = 999;
                System.out.println("finally2:" + resultInt);

            } catch (Exception e) {
                resultInt = 8;
                System.out.println("error:" + resultInt);
                return resultInt;
            }
        }
    }

2. finally多个资源关闭正确代码

  private static int testCatchError() {
        int resultInt = 0;

        try {
            resultInt = 777;
            System.out.println(resultInt);
        } catch (Exception e) {
            resultInt = 7;
            System.out.println("error:" + resultInt);
            return resultInt;
        } finally {
            try {
                resultInt = 888;
                System.out.println("finally1:" + resultInt);
            } catch (Exception e) {
                resultInt = 8;
                System.out.println("error:" + resultInt);
            }

            try {
                resultInt = 999;
                System.out.println("finally2:" + resultInt);
            } catch (Exception e) {
                resultInt = 9;
                System.out.println("error:" + resultInt);
            }
        }
        return resultInt;
    }

---

这里的正确看具体需求， 我这里希望finally（行24，行16）和try catch （行8）中如果都出现异常 ,try catch （行8）中的结果返回

二 . 结论

finally优先级高try（用词不准），只有try和catch有return,finally中没有return,那么有无异常，finally操作try中返回值最终返回也是 try（无异常）或catch（有异常）的赋值

int a = 0;
try{
 int errAnchor = 1/0；
 return a = 1;
}
catch（Exception e）{ return a = 2; }
finally{ 
  try{
    a = 3
    int errAnchor = 1/0；
    return a ;
  } 
  catch（Exception e）{return a;}
}
return a ;
/* 代码执行try{}块时如果有异常 ，tyr{}中的return就被跳过了，就会进入catch（）{}，虽然catch（）{}中有return，但 finally必定执行所以接着执行finally{}，如果finally中try{}有异常则和前面一样return会被跳过。这时候如果finally中catch（）{}没有return 则使用 行5catch（）{}的return，如果finally中try{}没有异常，则使用finally中try{}的return
	如果try{} catch（）{} 和finally{}都没有return ，
*/

---

1. finally 中不要出现 return

try ,catch ,finally 中都出现 return ，即使catch 出现异常也是返回finally中return 结果

2.  private static int testCatchError() {
           int resultInt = 0;
           int errAnchor;
      
           try {
               resultInt = 777;
               System.out.println(resultInt);
               
           } catch (Exception e) {
               resultInt = 7;
               System.out.println("error:" + resultInt);
               return resultInt;
           } finally {
               try {
                   resultInt = 888;
                   System.out.println("finally1:" + resultInt);
                   errAnchor = 1 / 0;
                   resultInt = 999;
                   System.out.println("finally2:" + resultInt);
               } catch (Exception e) {
                   resultInt = 8;
                   System.out.println("error:" + resultInt);
               }
           }
                   return resultInt;
       }
      
   console：
   777
   finally1:888
   error:8
   结果:8
   
   

   finally1 行17出现异常 finally2行 18将不会执行，finally一般关闭资源,关闭多个资源的情况下，finally2处资源将得不到释放

三 . 论证

这里放几个链接.自己写的demo就懒得放了

1. https://www.jianshu.com/p/705faad2c33f

2. https://blog.csdn.net/qq_20009015/article/details/102321021?utm_medium=distribute.pc_relevant.none-task-blog-2_defaultbaidujs_baidulandingword~default-1.no_search_link&spm=1001.2101.3001.4242.2&utm_relevant_index=2

3. https://blog.csdn.net/sinat_22594643/article/details/80509266?spm=1001.2101.3001.6650.2&utm_medium=distribute.pc_relevant.none-task-blog-2~default~CTRLIST~default-2.no_search_link&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2~default~CTRLIST~default-2.no_search_link&utm_relevant_index=3

4. http://c.biancheng.net/view/6669.html