About Question enthuware.ocajp.i.v7.2.1148 :

[soncrash]

Java is weird... I also typed for unreachable block - it wont compile...
Also when I pasted this code into Eclipse it warns me that "finally block does not complete normally".

Nice question however

[Rinkesh]

Suppose that seed=11 so I will get 1 instead of 7 which is returned in finally because finally is not executed compulsorily unless and until we execute the code in try block or if there is a System.exit(),Am I Right??

[admin]

finally isn't executed if there is a System.exit is executed in the try block or catch block otherwise. Except that, a finally block is always executed.

[Rinkesh]

Okay thank you Paul.

[__JJ__]

Funny I had thought that having just "default:" would be a syntax error but clearly it isn't. All the following are legal:

Code: Select all

        switch( 3 ){
           default : 
        }
        switch( 4 ){
           case 5 :
        }
        switch( 3 ){
           default : ;
        }
        switch( 3 ){
           default : {}
        }

[Solid15]

Yesterday I had a mock question saying it doesn't compile of you return in both the try, catch and final block. (I think it was in mock exam 3, otherwise it was in mock exam 5). I believe it had to do with unreachable code. I answered this question wrong because I thought it would return the finally return. Now I see this question and I answer "does not compile" and it is wrong, because apparently the finally return can overwrite the previous return.

I'm confused. Doesn't the compiler know the finally return is unreachable because of the if-else clause within the try-block, as opposed to the previous example (if I remember the details of the previous question correctly).

Some testing in my IDE indicates that it compiles. So either the question from the previous mock test was wrong, or something else is involved there that I don't understand.

QUESTION: is there a way to make try{return}catch{return}finally{return} not compile? If so, how?

[admin]

I couldn't find any explanation text that says anything like, "it doesn't compile of you return in both the try, catch and final block.".

finally block is always executed, so, a return statement in finally cannot be unreachable just because it is present in the finally block or because there is a return statement or an if/else statement in the try or catch blocks.

The rules of unreachable code are same for all types of blocks. So, a simple code like this:

Code: Select all

try{
   return;
}catch(Exception e){
   return;
}catch(RuntimeException e){ //this catch block is unreachable
   return;
}     
finally{
    if(true ) return ;
    else return;
    return; //this is unreachable
}

will not compile.

If you can find the question that you think has a problem, let us know.

[Denyo1986]

Yesterday I had a mock question saying it doesn't compile of you return in both the try, catch and final block. (I think it was in mock exam 3, otherwise it was in mock exam 5). I believe it had to do with unreachable code. I answered this question wrong because I thought it would return the finally return. Now I see this question and I answer "does not compile" and it is wrong, because apparently the finally return can overwrite the previous return.

I'm confused. Doesn't the compiler know the finally return is unreachable because of the if-else clause within the try-block, as opposed to the previous example (if I remember the details of the previous question correctly).

Some testing in my IDE indicates that it compiles. So either the question from the previous mock test was wrong, or something else is involved there that I don't understand.

QUESTION: is there a way to make try{return}catch{return}finally{return} not compile? If so, how?

I am with you. Thought of the same question, also opted for unreachable code and failed. Will supply the question if I find it again.

[admin]

You might want to check out questions 2.984, 2.1200, and 2.1323. They touch upon reachable statement issue but are different.
(In ETS Viewer s/w, you can do Control + Q and then enter 2.984 to open that question.)

[Denyo1986]

Great. Supplying those numbers was super-helpful. Thanks admin.

The question I had in mind was 2.1200. I looked at it again and found the difference. In that question there is another return statement after the try/catc/finally block and that causes all the issues. So its not really comparable to this situation (but seemed so from my memory).

Thanks for being such a great support here...really good exam prep experience

[gadsgadsx]

Can we say that this code will always return 7 in the try-catch-finally block, given that the input is less than 10? Because finally will execute anyways, making no difference if the exception is thrown or not?

[admin]

Yes, when a finally clause has a return statement then this return statement supersedes any return statement that the try block or the catch blocks might have. So this method will always return 7.

The explanation has now been enhanced to include this point.