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

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