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Java异常捕获之try-catch-finally-return的执行顺序

几个T的资料等你来白嫖
双倍快乐

情况1:try块中没有抛出异常try和finally块中都有return语句

public static int NoException(){
  int i=10;
  try{
   System.out.println("i in try block is"+i);
   return --i;
  }catch(Exception e){
   --i;
   System.out.println("i in catch - form try block is"+i);
   return --i;
  }finally{

   System.out.println("i in finally - from try or catch block is"+i);
   return --i;
  }
 }

执行结果:

i in try block is10
i in finally – from try or catch block is9
the method value is8

执行顺序:执行try块,执行到return语句时,先执行return的语句,–i,但是不返回到main 方法,执行finally块,遇到finally块中的return语句,执行–i,并将值返回到main方法,这里就不会再回去返回try块中计算得到的值

情况2:try块中没有抛出异常,仅try中有return语句

代码:

public static int NoException(){
        int i=10;
        try{
            System.out.println("i in try block is--"+i);
            return --i;
        }catch(Exception e){
            --i;
            System.out.println("i in catch - form try block is--"+i);
            return --i;
        }finally{

            System.out.println("i in finally - from try or catch block is--"+i);
            --i;
            System.out.println("i in finally block is--"+i);
            //return --i;
        }
    }

执行结果:

i in try block is–10
i in finally – from try or catch block is–9
i in finally block is–8
the method value is–9

顺序:try中执行完return的语句后,不返回,执行finally块,finally块执行结束后,返回到try块中,返回i在try块中最后的值

情况3:try块中抛出异常try,catch,finally中都有return语句

代码:

public static int WithException(){
        int i=10;
        try{
            System.out.println("i in try block is--"+i);
            i = i/0;
            return --i;
        }catch(Exception e){
            System.out.println("i in catch - form try block is--"+i);
            --i;
            System.out.println("i in catch block is--"+i);
            return --i;
        }finally{

            System.out.println("i in finally - from try or catch block is--"+i);
            --i;
            System.out.println("i in finally block is--"+i);
            return --i;
        }
    }

执行结果:

i in try block is–10
i in catch – form try block is–10
i in catch block is–9
i in finally – from try or catch block is–8
i in finally block is–7
the method value is–6

顺序,抛出异常后,执行catch块,在catch块的return的–i执行完后,并不直接返回而是执行finally,因finally中有return语句,所以,执行,返回结果6

情况4,catch中有return,finally中没有,同上,执行完finally语句后,依旧返回catch中的执行return语句后的值,而不是finally中修改的值

情况5:try和catch中都有异常,finally中无return语句

public static int CatchException(){
        int i=10;
        try{
            System.out.println("i in try block is--"+i);
            i=i/0;
            return --i;
        }catch(Exception e){
            System.out.println("i in catch - form try block is--"+i);
            int j = i/0;
            return --i;
        }finally{

            System.out.println("i in finally - from try or catch block is--"+i);
            --i;
            System.out.println("i in finally block is--"+i);
            //return --i;
        }
    }

结果:

i in try block is–10
i in catch – form try block is–10
i in finally – from try or catch block is–10
i in finally block is–9
Exception in thread "main" java.lang.ArithmeticException: / by zero
at exception.ExceptionTest0123.CatchException(ExceptionTest0123.java:29)
at exception.ExceptionTest0123.main(ExceptionTest0123.java:17)

执行顺序:在try块中出现异常,到catch中,执行到异常,到finally中执行,finally执行结束后判断发现异常,抛出

情况6:try,catch中都出现异常,在finally中有返回

public static int CatchException(){
        int i=10;
        try{
            System.out.println("i in try block is--"+i);
            i=i/0;
            return --i;
        }catch(Exception e){
            System.out.println("i in catch - form try block is--"+i);
            int j = i/0;
            return --i;
        }finally{

            System.out.println("i in finally - from try or catch block is--"+i);
            --i;
            System.out.println("i in finally block is--"+i);
            return --i;
        }
    }

运行结果:

i in try block is–10
i in catch – form try block is–10
i in finally – from try or catch block is–10
i in finally block is–9
the method value is–8

执行顺序:try块中出现异常到catch,catch中出现异常到finally,finally中执行到return语句返回,不检查异常

没有catch,只有try和finally时,执行顺序和上面的几种情况差不多,只是少了catch块的执行

欢迎大家补充指正

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