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id="bodyColumn"><div class="contentBox"><div class="section"><a name="Java_Logging_Rules"></a><h2>Java Logging Rules</h2>
				

  
The Java Logging ruleset contains a collection of rules that find questionable usages of the logger.
  

    
	
	<div class="subsection"><a name="MoreThanOneLogger"></a><h3>MoreThanOneLogger</h3>
		<p>Since: PMD 2.0</p>
		<p>
Normally only one logger is used in each class.
     </p>
		
		
		    
		    
    		    
    		    
    		    

    		    <p>This rule is defined by the following Java class:
    		    <a href="../xref/net/sourceforge/pmd/rules/MoreThanOneLogger.html">net.sourceforge.pmd.rules.MoreThanOneLogger</a>
    		    </p>
		    
	    
	    
        
        
        <p>Example:</p>
            
    <div class="source"><pre>
                
 
class Foo{
    Logger log = Logger.getLogger(Foo.class.getName());
    // It is very rare to see two loggers on a class, normally
    // log information is multiplexed by levels
    Logger log2= Logger.getLogger(Foo.class.getName());
}

     
            </pre></div>
  
        

        
        
            
        

	</div>


     
	
	<div class="subsection"><a name="LoggerIsNotStaticFinal"></a><h3>LoggerIsNotStaticFinal</h3>
		<p>Since: PMD 2.0</p>
		<p>
In most cases, the Logger can be declared static and final.
     </p>
		
		
		    
    			<p>This rule is defined by the following XPath expression:</p>
    			
    			
    <div class="source"><pre>
                 
//VariableDeclarator
 [parent::FieldDeclaration]
 [../Type/ReferenceType
  /ClassOrInterfaceType[@Image='Logger']
   and
  (..[@Final='false'] or ..[@Static = 'false'] ) ]
                
             </pre></div>
  
		    
		    
	    
	    
        
        
        <p>Example:</p>
            
    <div class="source"><pre>
                
 
class Foo{
    Logger log = Logger.getLogger(Foo.class.getName());
    // It is much better to declare the logger as follows 
    // static final Logger log = Logger.getLogger(Foo.class.getName());
}

     
            </pre></div>
  
        

        
        
            
        

	</div>

    




    
	
	<div class="subsection"><a name="SystemPrintln"></a><h3>SystemPrintln</h3>
		<p>Since: PMD 2.1</p>
		<p>
System.(out|err).print is used, consider using a logger.
     </p>
		
		
		    
    			<p>This rule is defined by the following XPath expression:</p>
    			
    			
    <div class="source"><pre>
                 
//Name[
    starts-with(@Image, 'System.out.print')
    or
    starts-with(@Image, 'System.err.print')
    ]
                
             </pre></div>
  
		    
		    
	    
	    
        
        
        <p>Example:</p>
            
    <div class="source"><pre>
                
 
class Foo{
    Logger log = Logger.getLogger(Foo.class.getName());
    public void testA () {
        System.out.println("Entering test");
        // Better use this
        log.fine("Entering test");
    }
}

     
            </pre></div>
  
        

        
        
            
        

	</div>


    
	
	<div class="subsection"><a name="AvoidPrintStackTrace"></a><h3>AvoidPrintStackTrace</h3>
		<p>Since: PMD 3.2</p>
		<p>
Avoid printStackTrace(); use a logger call instead.
           </p>
		
		
		    
    			<p>This rule is defined by the following XPath expression:</p>
    			
    			
    <div class="source"><pre>

//PrimaryExpression
 [PrimaryPrefix/Name[contains(@Image,'printStackTrace')]]
 [PrimarySuffix[not(boolean(Arguments/ArgumentList/Expression))]]

             </pre></div>
  
		    
		    
	    
	    
        
        
        <p>Example:</p>
            
    <div class="source"><pre>
                

class Foo {
 void bar() {
  try {
   // do something
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

           
            </pre></div>
  
        

        
        
            
        

	</div>

    

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