Class AvoidNestedBlocksCheck

Finds nested blocks (blocks that are used freely in the code).

Rationale: Nested blocks are often leftovers from the debugging process, they confuse the reader.

For example this Check finds the obsolete braces in

 public void guessTheOutput()
 {
   int whichIsWhich = 0;
   {
     whichIsWhich = 2;
   }
   System.out.println("value = " + whichIsWhich);
 }
 

and debugging / refactoring leftovers such as

 // if (conditionThatIsNotUsedAnyLonger)
 {
   System.out.println("unconditional");
 }
 

A case in a switch statement does not implicitly form a block. Thus to be able to introduce local variables that have case scope it is necessary to open a nested block. This is supported, set the allowInSwitchCase property to true and include all statements of the case in the block.

 switch (a)
 {
   case 0:
     // Never OK, break outside block
     {
       x = 1;
     }
     break;
   case 1:
     // Never OK, statement outside block
     System.out.println("Hello");
     {
       x = 2;
       break;
     }
   case 2:
     // OK if allowInSwitchCase is true
     {
       System.out.println("Hello");
       x = 3;
       break;
     }
 }
 

• Property allowInSwitchCase - Allow nested blocks if they are the only child of a switch case. Type is boolean. Default value is false.

To configure the check:

 <module name="AvoidNestedBlocks"/>
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• block.nested