pmd | 易学教程

Iterating over the content of a text file line by line - is there a best practice? (vs. PMD's AssignmentInOperand)

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We have a Java Application that has a few modules that know to read text files. They do it quite simply with a code like this: BufferedReader br = new BufferedReader(new FileReader(file)); String line = null; while ((line = br.readLine()) != null) { ... // do stuff to file here } I ran PMD on my project and got the ' AssignmentInOperand ' violation on the while (...) line. Is there a simpler way of doing this loop other than the obvious: String line = br.readLine(); while (line != null) { ... // do stuff to file here line = br.readLine(); } Is this considered a better practice? (although we

Avoid printStackTrace(); use a logger call instead

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In my application, I am running my code through PMD.It shows me this message: Avoid printStackTrace(); use a logger call instead. What does that mean? It means you should use logging framework like logback or log4j and instead of printing exceptions directly: e.printStackTrace(); you should log them using this frameworks' API: log.error("Ops!", e); Logging frameworks give you a lot of flexibility, e.g. you can choose whether you want to log to console or file - or maybe skip some messages if you find them no longer relevant in some environment. If you call printStackTrace() on an exception the

RegExp matching string not starting with my

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For PMD I'd like to have a rule which warns me of those ugly variables which start with my. This means I have to accept all variables which do NOT start with my. So, I need a RegEx (re) which behaves as follows: re.match('myVar') == false re.match('manager') == true re.match('thisIsMyVar') == true re.match('myOtherVar') == false re.match('stuff') == true I've tried different ones (will list them here later, sorry, no access to them right now) but haven't got it working yet. You could either use a lookahead assertion like others have suggested. Or, if you just want to use basic regular

What is the reason for these PMD rules?

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DataflowAnomalyAnalysis: Found 'DD'-anomaly for variable 'variable' (lines 'n1'-'n2'). DataflowAnomalyAnalysis: Found 'DU'-anomaly for variable 'variable' (lines 'n1'-'n2'). DD and DU sound familiar...I want to say in things like testing and analysis relating to weakest pre and post conditions, but I don't remember the specifics. NullAssignment: Assigning an Object to null is a code smell. Consider refactoring. Wouldn't setting an object to null assist in garbage collection, if the object is a local object (not used outside of the method)? Or is that a myth? MethodArgumentCouldBeFinal:

PMD violationSuppressXPath for all REST @GET methods?

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问题 I am trying to narrow down the PMD rules, how can I exclude all REST methods which are annotated with @GET from PMD checks? 回答1: We are using for example this rules to suppress checks on REST methods for final declaration. Maybe you need similar? <rule ref="rulesets/java/optimizations.xml/MethodArgumentCouldBeFinal"> <properties>  <property name="violationSuppressXPath" value=" //ClassOrInterfaceBodyDeclaration/Annotation/MarkerAnnotation//Name[@Image='GET'] | /

Logger vs. System.out.println

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问题 I'm using the PMD plugin for eclipse and it gives me an error when using System.out.println() with the explanation: System.(out|err).print is used, consider using a logger. My question is - What is a Logger? How is it used to print to the screen? Why is it better? 回答1: See this short introduction to log4j. The issue is in using System.out to print debugging or diagnostic information. It is a bad practice because you cannot easily change log levels, turn it off, customize it, etc. However if

Iterating over the content of a text file line by line - is there a best practice? (vs. PMD's AssignmentInOperand)

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问题 We have a Java Application that has a few modules that know to read text files. They do it quite simply with a code like this: BufferedReader br = new BufferedReader(new FileReader(file)); String line = null; while ((line = br.readLine()) != null) { ... // do stuff to file here } I ran PMD on my project and got the ' AssignmentInOperand ' violation on the while (...) line. Is there a simpler way of doing this loop other than the obvious: String line = br.readLine(); while (line != null) { ...

RegExp matching string not starting with my

阅读更多关于 RegExp matching string not starting with my

问题 For PMD I'd like to have a rule which warns me of those ugly variables which start with my. This means I have to accept all variables which do NOT start with my. So, I need a RegEx (re) which behaves as follows: re.match('myVar') == false re.match('manager') == true re.match('thisIsMyVar') == true re.match('myOtherVar') == false re.match('stuff') == true I've tried different ones (will list them here later, sorry, no access to them right now) but haven't got it working yet. 回答1: You could

What is the reason for these PMD rules?

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问题 DataflowAnomalyAnalysis: Found \'DD\'-anomaly for variable \'variable\' (lines \'n1\'-\'n2\'). DataflowAnomalyAnalysis: Found \'DU\'-anomaly for variable \'variable\' (lines \'n1\'-\'n2\'). DD and DU sound familiar...I want to say in things like testing and analysis relating to weakest pre and post conditions, but I don\'t remember the specifics. NullAssignment: Assigning an Object to null is a code smell. Consider refactoring. Wouldn\'t setting an object to null assist in garbage collection,