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Eclipse 3.6.1 gives invalid null warning for the following test case: public class NullWarning { public static void someMethod(String param1) { boolean b = (param1 == null); if (b) { // do something } // this line gives incorrect warning: // Potential null pointer access: The variable param1 may be null at this location param1.trim(); } } -- Configuration Details -- Product: Eclipse 1.3.1.20100913-1228 (org.eclipse.epp.package.jee.product) Installed Features: org.eclipse.jdt 3.6.1.r361_v20100714-0800-7z8XFUSFLFlmgLc5z-Bvrt8-HVkH
The check (param1 == null) tells the compiler that the developer expects both null and non-null values. So any dereference of param1 after this check is flagged as a potential null dereference. If the check is only for robustness and null is actually not expected here, then perhaps an assert is a better way to reflect your intention. Once bug 186342 is released you may even avoid the check altogether by declaring the parameter as "@NonNull String param1".
How about this: int b = param1 == null ? 1 : 2; if (StringUtils.isNotBlank(param1) { param1.trim(); } I still receive that warning even when I used a method which checks for nullity. I believe this is raised because JDT is not inspecting methods recursively. (and this is quite reasonable) Is this the right behavior based on Java compiler spec, or is a JDT-specific warning? Thanks, Mohsen
(In reply to comment #2) > How about this: > int b = param1 == null ? 1 : 2; > > if (StringUtils.isNotBlank(param1) { > param1.trim(); > } > > I still receive that warning even when I used a method which checks for > nullity. I believe this is raised because JDT is not inspecting methods > recursively. (and this is quite reasonable) Is this the right behavior based on > Java compiler spec, or is a JDT-specific warning? > > Thanks, > Mohsen This is purely a JDT-specific warning. We currently dont do inter-procedural analysis, so passing a variable as a parameter to a method call makes no difference in our analysis. As Stephan already pointed out,fix for bug 186342 will make it convenient to specify null status of variables using annotations. I intend to close this as INVALID.
> This is purely a JDT-specific warning. We currently dont do inter-procedural > analysis, so passing a variable as a parameter to a method call makes no > difference in our analysis. As Stephan already pointed out,fix for bug 186342 > will make it convenient to specify null status of variables using annotations. > > I intend to close this as INVALID. Thanks for your explanation. Feel free to mark it INVALID.
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Verified for 3.7 M5
