Return in if statement causing unreachable code error

Question

The following code:

public static void print(ListNode p)
{
    System.out.print("[");
    if(p==null);
    {
        System.out.println("]");
        return;
    }
    ListNode k = p.getNext();
    //more code
}

causes the following compile error:

 ----jGRASP exec: javac -g Josephus_5_Rajolu.java

Josephus_5_Rajolu.java:53: error: unreachable statement
            ListNode k = p.getNext();
                     ^
1 error

 ----jGRASP wedge2: exit code for process is 1.
 ----jGRASP: operation complete.

Why is that happening? I am only returning if p = null. I want to do my other code if p!=null. Why is it unreachable?

Lessons to learn: (1) it is easy to write code that does something other than what you think it does, (2) your coding style can help your code to be cleaner. For example, if you placed your curly braces immediately to the right of the if statement you can reduce the chances you'll insert an incorrect simicolon. — Kevin Sitze, Nov 13 '12 at 23:59
Thanks for the tip. I have seen the curly brace next to the if statement many times and I have tried using it but because I got used to this style of coding, it feels awkward when I try doing that. Lesson 1 is very true. — golddove, Nov 22 '12 at 01:20

Madbreaks · Accepted Answer · 2012-12-19T18:15:58.287

12

There's a semicolon after your if statement.

edited Dec 19 '12 at 18:15

answered Nov 13 '12 at 23:43

Madbreaks

19,094
7
58
72

OH! I didn't catch that. Thanks! It says I can't mark correct answer for 13 minutes. I'll do it after 13 minutes. Thank you so much! – golddove Nov 13 '12 at 23:45
You're welcome. Sometimes a 2nd set of eyes is all it takes. – Madbreaks Nov 13 '12 at 23:45

score 3 · Answer 2 · answered Nov 13 '12 at 23:45

3

there is ; after if statement remove it it will work :)

answered Nov 13 '12 at 23:45

zaffargachal

802
7
21

score 2 · Answer 3 · answered Nov 13 '12 at 23:44

2

if(p==null); <-- remove the semicolon at the end

answered Nov 13 '12 at 23:44

Eugene Retunsky

13,009
4
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score 2 · Answer 4 · answered Nov 13 '12 at 23:44

2

maybe the ';' at the:
if(p==null);

answered Nov 13 '12 at 23:44

Barracuda

101
6

score 1 · Answer 5 · answered Nov 13 '12 at 23:47

1

remove the semicolon after your if

answered Nov 13 '12 at 23:47

Drew

24,851
10
43
78

score 1 · Answer 6 · answered Nov 13 '12 at 23:50

1

Where are you instantiating ListNode K?

It looks like to me that the issue is ListNode k is not being instantiated.

I think you need something like this. ListNode k = new ListNode();

Are you creating this within your class?

Also you have a ; after if(p==null); That needs to be removed.

answered Nov 13 '12 at 23:50

Thomas Vincent Blomberg

388
1
12

that is not the problem. I simply made the reference point to the p.getNext(). The semi-colon is the problem. Thank you! – golddove Nov 14 '12 at 00:00
I know the semi colon is the issue, but I did not see the instantiating and sometimes that can be a big issue. – Thomas Vincent Blomberg Nov 14 '12 at 00:01
the instantiating is right there though. in the line right above `\\more code` it says `ListNode k = p.getNext();` – golddove Nov 22 '12 at 01:16

Return in if statement causing unreachable code error

6 Answers6