How do I force implementations of a method to be inside a try-catch block in Java?

Question

This may be a Java question, or it may be an Eclipse question, I'm not positive.

I'm creating custom View in Android: HelpTextView extends View

I would like to override View.setVisibility(), forcing calls to HelpTextView.setVisibility() to be written inside try-catch (NullPointerException nex) blocks.

I added both a throws declaration to the method (which is what I thought would do the trick) as well as a throw command but no luck. Is this not working because it's simply never going to work (perhaps overriding just doesn't work that way) or am I doing something wrong?

Can you show your code – Satheesh Cheveri Dec 11 '13 at 16:14 — Satheesh Cheveri, Dec 11 '13 at 16:14

score 3 · Answer 1 · answered Dec 11 '13 at 16:15

3

NullPointerException is a subclass of RuntimeException. A RuntimeException is an unchecked exception, meaning that you do not need to catch it.

No matter how you declare your method, you cannot force a NullPointerException to be caught.

You can, however, create your own Exception and force that to be caught.

answered Dec 11 '13 at 16:15

Bryan Herbst

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Really? The Java documentation that I linked to begs to differ. – Bryan Herbst Dec 11 '13 at 16:17
what you said is correct. – RamonBoza Dec 11 '13 at 16:17
Tanis.7x is indeed correct. – Stuart Marks Dec 11 '13 at 16:18
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Heh, the guy who said you were incorrect deleted his comment. – Stuart Marks Dec 11 '13 at 16:19

score 3 · Answer 2 · answered Dec 11 '13 at 16:16

3

You can not override a method and add an exception which is not already declared in super method except RuntimeExceptions.

answered Dec 11 '13 at 16:16

Max Power

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score 2 · Accepted Answer · edited Dec 04 '17 at 04:28

2

You cannot do this because NullPointerException is a RuntimeException, which does not need to be caught by the caller.

Your best approach is to implement your own Exception.

public class HelpTextView extends View {

    public setThisVisibility(boolean isVisible) throws MyNullPointerException {
        ...
    }

}

and your MyNullPointerException cannot be RuntimeException

edited Dec 04 '17 at 04:28

Beeing Jk

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answered Dec 11 '13 at 16:17

RamonBoza

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How do I force implementations of a method to be inside a try-catch block in Java?

3 Answers3