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teaching:labs:mdse:2013:bug_descriptions:jt-bug-cor86 [2013/12/16 17:00] malte.mauelshagen |
teaching:labs:mdse:2013:bug_descriptions:jt-bug-cor86 [2018/05/09 01:59] (current) |
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| + | ====== Bug Cor 86 ====== | ||
| + | |||
| + | ===== Inspired by ===== | ||
| + | |||
| + | * [[..:..:..:..:..:findbugs.sourceforge.net:bugdescriptions.html#np_null_instanceof| NP_NULL_INSTANCEOF]] | ||
| + | |||
| + | ===== Original Description ===== | ||
| + | |||
| + | "This instanceof test will always return false, since the value being checked is guaranteed to be null. Although this is safe, make sure it isn't an indication of some misunderstanding or some other logic error. " -- 2013-12-16 | ||
| + | |||
| + | |||
| + | ===== Detailed Description ===== | ||
| + | |||
| + | The value that is checked with an instanceOf operation is **ensured** to be null (With the help of points-to-analysis). Therefore, there is probably a logical error in the code. No sample fix can be given. | ||
| + | |||
| + | ===== Sample Problem Scenario ===== | ||
| + | |||
| + | |||
| + | <code Java> | ||
| + | if(a instanceof String){ | ||
| + | System.out.println("BUUG!"); | ||
| + | } | ||
| + | </Code> | ||
| + | |||
| + | ===== Sample Counter Scenario ===== | ||
| + | |||
| + | |||
| + | <code Java> | ||
| + | private static Object returnsNotNull(){ | ||
| + | return new Object(); | ||
| + | } | ||
| + | |||
| + | Object o = null; | ||
| + | o = returnsNotNull(); | ||
| + | boolean b = o instanceof Object; | ||
| + | System.out.println(b); | ||
| + | </Code> | ||
| + | |||
| + | |||
| + | ===== Sample Fix ===== | ||
| + | |||
| + | No fix provided. | ||
| + | |||
| + | ===== Evaluation Results ===== | ||
| + | |||
| + | ^ Benchmark project ^ Precision ^^^ Recall ^^^ | ||
| + | | | FB | JT | Delta | FB | JT | Delta | | ||
| + | | MDSE Lab | 100% | 66% | - | 66% | 33% | -% | | ||
| + | | Apache Tomcat | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | Argo UML | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | AWT | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | Jakarta | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | Java IO | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | JHotDraw | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | jrefactory | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | JServlet | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | JUnit | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | Lexi | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | Mapper XML | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | nutch | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | PMD | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | | quickuml | 100% | 100% | 0 | 100% | 100% | 0% | | ||
| + | FB = FindBugs, JT = JTransformer, Delta = JTransformer - FindBug | ||
| + | |||
| + | |||
teaching/labs/mdse/2013/bug_descriptions/jt-bug-cor86.txt · Last modified: 2018/05/09 01:59 (external edit)
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