How to write following code with Conditional(Ternary) Operator?

Question

I am just playing with my code. The code in if else block can be written with conditional operator (? :). how to write following code with Conditional Operator.

  import com.itextpdf.text.Document;

public class TEst {
    public static void main(String[] args) {
        Document doc=null;
        try{
         doc=new Document();
        //some operation.
        }catch(Exception e){

        }finally{
            doc!=null? doc.close():"";

            //if(doc!=null){
            //  doc.close();
            //}
        }
    }

Eclipse suggestion :

Multiple markers at this line

Type mismatch: cannot convert from null to boolean
Syntax error on token "!=", invalid AssignmentOperator

Does `doc.close()` return anything? If not, it can't be used in the ternary conditional operator. — Eran, Nov 30 '15 at 10:29
also i´d consider using the `try-with-ressources` version here to close the `Document`. — SomeJavaGuy, Nov 30 '15 at 10:30
then you´d need to assign `doc.close()` to a boolean variable, and include something like `false` for the else part. — SomeJavaGuy, Nov 30 '15 at 10:31

ParkerHalo · Accepted Answer · 2015-11-30T10:36:20.903

4

You could use the ternary operator here (using a dummy boolean and not using it again):

boolean dummy = doc != null ? doc.close() : false;

But i would highly recommend not using this kind of code. If you think a "1-liner" might be readable here consider doing something like:

if (doc!=null) doc.close();

EDIT:

Explanation why not to use this kind of code:

You would create a boolean which is never used again without gaining anything.

The ternary operator is not faster than an if condition
The code becomes unreadable in this case
the boolean dummy still contains a boolean value if doc was null

edited Nov 30 '15 at 10:36

answered Nov 30 '15 at 10:32

ParkerHalo

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But what is the use of that boolean ? :) – Suresh Atta Nov 30 '15 at 10:33
"But i would highly recommend not using this kind of code" I agree, but please explain why. – Andy Turner Nov 30 '15 at 10:33
@sᴜʀᴇsʜᴀᴛᴛᴀ there would be no use ;) It would just exist to be able to use the ternary operator – ParkerHalo Nov 30 '15 at 10:34

score 3 · Answer 2 · answered Nov 30 '15 at 10:30

3

No. Ternary operator can't be used this way.

//if(doc!=null){
    //  doc.close();
    //}

If you closely look the code commented, there is no else part at all. You just have only if and ternary operator needs an else for sure. Hence not possible.

answered Nov 30 '15 at 10:30

Suresh Atta

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How to write following code with Conditional(Ternary) Operator?

2 Answers2