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Bug 212748 - Adding warnings for misuse of the new literal underscores for primitive values
Summary: Adding warnings for misuse of the new literal underscores for primitive values
Status: NEW
Alias: None
Product: java
Classification: Unclassified
Component: Hints (show other bugs)
Version: 7.1.2
Hardware: PC Windows 7
: P3 normal (vote)
Assignee: Svata Dedic
Depends on:
Reported: 2012-05-20 11:13 UTC by gliesian
Modified: 2013-09-02 14:19 UTC (History)
0 users

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Exception Reporter:


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Description gliesian 2012-05-20 11:13:45 UTC
Java 7 allows for underscored in literals (Reference -

For example, 

int value = 1000; 

could be written as

int value = 1_000;

The issue is, if it's written as

int value = 1_00_0;

it equates to 1000, but the IDE doesn't tell the user of possible mistake.

Yes, 1_00_0 isn't going to happen... but this may:


Notice the missing zero... and yes, this is what the underscores is supposed to help with.  

My recommendation is to have a warning glyph shown in the gutter to the left, when a 0 is missing between underscores, as I believe that there is no reason to have a set of two (and not three) digits between underscores.

Thanks for the consideration, Robert
Comment 1 gliesian 2012-05-21 22:30:14 UTC
I may have made a mistake opening this...

You may want to use the underscores for other reasons, such as credit cards...

e.g., long creditCardNumber = 5555_5555_5555_5555;

However, if you thing about it, a credit should probably be a string.

This issue requires some thought before correcting.
Comment 2 gliesian 2012-05-21 22:44:11 UTC
Here's another example that goes against my reasoning: 

int socialSecurityID = 111_11_1111;
Comment 3 Jan Lahoda 2012-05-22 12:22:08 UTC
So far, there is only "Add Underscores" (Tools/Options/Editor/Hints/Language=Java/JDK 5 and later/Add Underscores) - disabled by default. But that pushes the same format to all literals, even those that do not have any underscores. It might be reasonable to add a warning in the future, that would only check consistency for literals which actually use underscores.