Class EmptyBlockCheck

Checks for empty blocks. This check does not validate sequential blocks.

Sequential blocks won't be checked. Also, no violations for fallthrough:

 switch (a) {
   case 1:                          // no violation
   case 2:                          // no violation
   case 3: someMethod(); { }        // no violation
   default: break;
 }
 

NOTE: This check processes LITERAL_CASE and LITERAL_DEFAULT separately. Verification empty block is done for single most nearest case or default.

• Property option - specify the policy on block contents. Type is com.puppycrawl.tools.checkstyle.checks.blocks.BlockOption. Default value is statement.
• Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: LITERAL_WHILE, LITERAL_TRY, LITERAL_FINALLY, LITERAL_DO, LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, INSTANCE_INIT, STATIC_INIT, LITERAL_SWITCH, LITERAL_SYNCHRONIZED.

To configure the check:

 <module name="EmptyBlock"/>
 

To configure the check for the text policy and only try blocks:

 <module name="EmptyBlock">
   <property name="option" value="text"/>
   <property name="tokens" value="LITERAL_TRY"/>
 </module>
 

To configure the check for default in switch block:

 <module name="EmptyBlock">
   <property name="tokens" value="LITERAL_DEFAULT"/>
 </module>
 

Result:

 switch (a) {
   default:        // no violation for "default:" as empty block belong to "case 1:"
   case 1: { }
 }
 

 switch (a) {
   case 1:
   default: { }  // violation
 }
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• block.empty
• block.noStatement