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Empty Code

The Empty Code ruleset contains rules that find empty statements of any kind (empty method, empty block statement, empty try or catch block,…).

EmptyCatchBlock

Since: PMD 0.1

Priority: 3

Empty Catch Block finds instances where an exception is caught, but nothing is done.
In most circumstances, this swallows an exception which should either be acted on or reported.

    
//CatchStatement
 [count(Block/BlockStatement) = 0 and ($allowCommentedBlocks != 'true' or Block/@containsComment = 'false')]
 [FormalParameter/Type/ReferenceType
   /ClassOrInterfaceType[@Image != 'InterruptedException' and @Image != 'CloneNotSupportedException']
 ]
 
             

Example(s):

  
public void doSomething() {
  try {
    FileInputStream fis = new FileInputStream("/tmp/bugger");
  } catch (IOException ioe) {
      // not good
  }
}
 
      

This rule has the following properties:

Name Default Value Description
allowCommentedBlocks false Empty blocks containing comments will be skipped

EmptyIfStmt

Since: PMD 0.1

Priority: 3

Empty If Statement finds instances where a condition is checked but nothing is done about it.


//IfStatement/Statement
 [EmptyStatement or Block[count(*) = 0]]
 
              

Example(s):

    
public class Foo {
 void bar(int x) {
  if (x == 0) {
   // empty!
  }
 }
}
 
       

EmptyWhileStmt

Since: PMD 0.2

Priority: 3

Empty While Statement finds all instances where a while statement does nothing.
If it is a timing loop, then you should use Thread.sleep() for it; if it is a while loop that does a lot in the exit expression, rewrite it to make it clearer.


//WhileStatement/Statement[./Block[count(*) = 0]  or ./EmptyStatement]

              

Example(s):

  
void bar(int a, int b) {
	while (a == b) {
	// empty!
	}
}
 
       

EmptyTryBlock

Since: PMD 0.4

Priority: 3

Avoid empty try blocks - what’s the point?


//TryStatement/Block[1][count(*) = 0]

              

Example(s):

  
public class Foo {
 public void bar() {
  try {
  } catch (Exception e) {
    e.printStackTrace();
  }
 }
}

      

EmptyFinallyBlock

Since: PMD 0.4

Priority: 3

Empty finally blocks serve no purpose and should be removed.


//FinallyStatement[count(Block/BlockStatement) = 0]
 
              

Example(s):

  
public class Foo {
 public void bar() {
  try {
    int x=2;
   } finally {
    // empty!
   }
 }
}
 
      

EmptySwitchStatements

Since: PMD 1.0

Priority: 3

Empty switch statements serve no purpose and should be removed.


//SwitchStatement[count(*) = 1]
 
              

Example(s):

  
public void bar() {
	int x = 2;
	switch (x) {
	// once there was code here
	// but it's been commented out or something
	}
}

      

EmptySynchronizedBlock

Since: PMD 1.3

Priority: 3

Empty synchronized blocks serve no purpose and should be removed.


//SynchronizedStatement/Block[1][count(*) = 0]

              

Example(s):


public class Foo {
 public void bar() {
  synchronized (this) {
   // empty!
  }
 }
}

      

EmptyStatementNotInLoop

Since: PMD 1.5

Priority: 3

An empty statement (or a semicolon by itself) that is not used as the sole body of a ‘for’ or ‘while’ loop is probably a bug. It could also be a double semicolon, which has no purpose and should be removed.


//EmptyStatement
 [not(
       ../../../ForStatement
       or ../../../WhileStatement
       or ../../../BlockStatement/ClassOrInterfaceDeclaration
       or ../../../../../../ForStatement/Statement[1]
        /Block[1]/BlockStatement[1]/Statement/EmptyStatement
       or ../../../../../../WhileStatement/Statement[1]
        /Block[1]/BlockStatement[1]/Statement/EmptyStatement)
 ]

                

Example(s):


public void doit() {
      // this is probably not what you meant to do
      ;
      // the extra semicolon here this is not necessary
      System.out.println("look at the extra semicolon");;
}

       

EmptyInitializer

Since: PMD 5.0

Priority: 3

Empty initializers serve no purpose and should be removed.


//Initializer/Block[count(*)=0]

                 

Example(s):

   
public class Foo {

   static {} // Why ?

   {} // Again, why ?

}
    
    

EmptyStatementBlock

Since: PMD 5.0

Priority: 3

Empty block statements serve no purpose and should be removed.

          
//BlockStatement/Statement/Block[count(*) = 0]
          
          

Example(s):

    
public class Foo {

   private int _bar;

   public void setBar(int bar) {
      { _bar = bar; } // Why not?
      {} // But remove this.
   }

}
    
    

EmptyStaticInitializer

Since: PMD 1.5

Priority: 3

An empty static initializer serve no purpose and should be removed.


//Initializer[@Static='true']/Block[count(*)=0]

                 

Example(s):

   
public class Foo {
	static {
	// empty
	}
}