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Bug Pattern
by Balaji Varanasi
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Hello,
I was refactoring some of my code and I ended up with a bug that FindBugs wasnot able to detect. Here is a simple version of the code: public void main(String args[]) { int value = 1; // Do some stuff if(value == 1) { for(int i = 0; i < 10; i++) { if(value == 2) { // Do something } else if(value == 3) { // Do something } } } } This is a simple oversight that might be worth if find bugs can catch. Thanks, Balaji _______________________________________________ Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Ignored return values
by Frank Jensen
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Hello,
FindBugs detects ignored return values from known methods: "hei".substring(1);//Reports: H C RV ... ignores return value However, it does not seem to detect ignored return values from my own methods: myObject.getIt(); //Reports nothing Would it be a good idea to make a more general rule about ignored return values? Some times the returned value is of no interest, but perhaps it is possible to detect when they probably are. For instance if 1. The called method have no (detectable) side effects 2. The called method is a getter Best Regards, Frank Jensen Oslo, Norway _______________________________________________ Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Re: Ignored return values
by Bill Pugh
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If you apply the annotation
edu.umd.cs.findbugs.annotations.CheckReturnValue, or javax.annotation.CheckReturnValue (from the JSR-305 reference implementation), FindBugs will report this. We aren't going to try to guess which methods should have their return value checked, at least not and generate the standard correctness warning. We might possibly generate a dodgy code warning. Bill On May 28, 2008, at 6:15 AM, Frank Jensen wrote: > Hello, > > FindBugs detects ignored return values from known methods: > > "hei".substring(1);//Reports: H C RV ... ignores return value > > > However, it does not seem to detect ignored return values from my own > methods: > > myObject.getIt(); //Reports nothing > > Would it be a good idea to make a more general rule about ignored > return > values? Some times the returned value is of no interest, but perhaps > it > is possible to detect when they probably are. For instance if > > 1. The called method have no (detectable) side effects > 2. The called method is a getter > > > Best Regards, > > Frank Jensen > Oslo, Norway > _______________________________________________ > Findbugs-discuss mailing list > Findbugs-discuss@... > https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss _______________________________________________ Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Re: Ignored return values
by Frank Jensen
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Will this not lead to very frequent use of CheckReturnValue? How about a
"CheckAllReturnValues" at the class-level? However, in my case the ignored return value could also have been found using another pattern. String findIt() { String it = null; if (true) { x.getIt(); } return it; } Or even shorter: String findIt() { String it = null; return it; } That is, returning a variable that is gaurranteed to be null. Is this pattern a better FindBugs candidate? Best Regards Frank On Wed, 2008-05-28 at 11:23 -0400, Bill Pugh wrote: > If you apply the annotation > edu.umd.cs.findbugs.annotations.CheckReturnValue, or > javax.annotation.CheckReturnValue (from the JSR-305 reference > implementation), > FindBugs will report this. > > We aren't going to try to guess which methods should have their return > value checked, > at least not and generate the standard correctness warning. We might > possibly generate a dodgy code warning. > > Bill > > > > On May 28, 2008, at 6:15 AM, Frank Jensen wrote: > > > Hello, > > > > FindBugs detects ignored return values from known methods: > > > > "hei".substring(1);//Reports: H C RV ... ignores return value > > > > > > However, it does not seem to detect ignored return values from my own > > methods: > > > > myObject.getIt(); //Reports nothing > > > > Would it be a good idea to make a more general rule about ignored > > return > > values? Some times the returned value is of no interest, but perhaps > > it > > is possible to detect when they probably are. For instance if > > > > 1. The called method have no (detectable) side effects > > 2. The called method is a getter > > > > > > Best Regards, > > > > Frank Jensen > > Oslo, Norway > > _______________________________________________ > > Findbugs-discuss mailing list > > Findbugs-discuss@... > > https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss > Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Re: Ignored return values
by John Penix
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Hi Frank,
How is always returning null related to not checking the return value? John On Thu, May 29, 2008 at 12:09 AM, Frank Jensen <frank.jensen@...> wrote: > Will this not lead to very frequent use of CheckReturnValue? How about a > "CheckAllReturnValues" at the class-level? > > However, in my case the ignored return value could also have been found > using another pattern. > > String findIt() { > String it = null; > if (true) { > x.getIt(); > } > return it; > } > > Or even shorter: > > String findIt() { > String it = null; > > return it; > } > > That is, returning a variable that is gaurranteed to be null. > > Is this pattern a better FindBugs candidate? > > > Best Regards > > Frank > > > On Wed, 2008-05-28 at 11:23 -0400, Bill Pugh wrote: >> If you apply the annotation >> edu.umd.cs.findbugs.annotations.CheckReturnValue, or >> javax.annotation.CheckReturnValue (from the JSR-305 reference >> implementation), >> FindBugs will report this. >> >> We aren't going to try to guess which methods should have their return >> value checked, >> at least not and generate the standard correctness warning. We might >> possibly generate a dodgy code warning. >> >> Bill >> >> >> >> On May 28, 2008, at 6:15 AM, Frank Jensen wrote: >> >> > Hello, >> > >> > FindBugs detects ignored return values from known methods: >> > >> > "hei".substring(1);//Reports: H C RV ... ignores return value >> > >> > >> > However, it does not seem to detect ignored return values from my own >> > methods: >> > >> > myObject.getIt(); //Reports nothing >> > >> > Would it be a good idea to make a more general rule about ignored >> > return >> > values? Some times the returned value is of no interest, but perhaps >> > it >> > is possible to detect when they probably are. For instance if >> > >> > 1. The called method have no (detectable) side effects >> > 2. The called method is a getter >> > >> > >> > Best Regards, >> > >> > Frank Jensen >> > Oslo, Norway >> > _______________________________________________ >> > Findbugs-discuss mailing list >> > Findbugs-discuss@... >> > https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss >> > _______________________________________________ > Findbugs-discuss mailing list > Findbugs-discuss@... > https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss > Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Re: Ignored return values
by Bill Pugh
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I don't think that methods that always return null is a particularly
useful bug pattern. There are a number of methods that are simply defined as { return null ; } But we might be able to extract a pattern from: > String findIt() { > String it = null; > if (true) { > x.getIt(); > } > return it; > } Let me think about it a bit. Bill _______________________________________________ Findbugs-discuss mailing list Findbugs-discuss@... https://mailman.cs.umd.edu/mailman/listinfo/findbugs-discuss |
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Re: Ignored return values
by Frank Jensen
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