Final Local Variable Name Check, fixed bug with lambda's params, issue #747

src/main/java/com/puppycrawl/tools/checkstyle/checks/coding/FinalLocalVariableCheck.java

@@ -156,7 +156,8 @@ public class FinalLocalVariableCheck extends Check
 
             case TokenTypes.PARAMETER_DEF:
                 if (ScopeUtils.inInterfaceBlock(ast)
-                    || inAbstractOrNativeMethod(ast))
+                    || inAbstractOrNativeMethod(ast)
+                    || inLambda(ast))
                 {
                     break;
                 }
@@ -247,6 +248,16 @@ public class FinalLocalVariableCheck extends Check
         return false;
     }
 
+    /**
+     * Check if current param is lamda's param.
+     * @param paramDef {@link TokenTypes#PARAMETER_DEF parameter def}.
+     * @return true if current param is lamda's param.
+     */
+    private static boolean inLambda(DetailAST paramDef)
+    {
+        return paramDef.getParent().getParent().getType() == TokenTypes.LAMBDA;
+    }
+
     /**
      * Inserts a variable at the topmost scope stack
      * @param ast the variable to insert

src/test/java/com/puppycrawl/tools/checkstyle/checks/coding/FinalLocalVariableCheckTest.java

@@ -18,12 +18,14 @@
 ////////////////////////////////////////////////////////////////////////////////
 package com.puppycrawl.tools.checkstyle.checks.coding;
 
-import com.puppycrawl.tools.checkstyle.BaseCheckTestSupport;
-import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
+import static com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck.MSG_KEY;
+
+import java.io.File;
 
 import org.junit.Test;
 
-import static com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck.MSG_KEY;
+import com.puppycrawl.tools.checkstyle.BaseCheckTestSupport;
+import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
 
 public class FinalLocalVariableCheckTest
     extends BaseCheckTestSupport
@@ -121,4 +123,17 @@ public class FinalLocalVariableCheckTest
         };
         verify(checkConfig, getPath("coding/InputFinalLocalVariableEnhancedForLoopVariable.java"), expected);
     }
+
+    @Test
+    public void testLambda()
+        throws Exception
+    {
+        final DefaultConfiguration checkConfig =
+            createCheckConfig(FinalLocalVariableCheck.class);
+        checkConfig.addAttribute("tokens", "PARAMETER_DEF,VARIABLE_DEF");
+        final String[] expected = {};
+        verify(checkConfig, new File("src/test/resources-noncompilable/com/puppycrawl/"
+                + "tools/checkstyle/naming/InputFinalLocalVariableNameLambda.java").
+                getCanonicalPath(), expected);
+    }
 }

src/test/resources-noncompilable/com/puppycrawl/tools/checkstyle/naming/InputFinalLocalVariableNameLambda.java

@@ -0,0 +1,13 @@
+//Compilable with Java8
+package com.puppycrawl.tools.checkstyle.naming;
+
+public class InputFinalLocalVariableNameLambda {
+    
+    private void addTotalValueOfOrder(final AugmentedOrder order) {
+    final BigDecimal totalValueOfOrder = order.getTransactions().stream()
+            .reduce(BigDecimal.ZERO,
+                    (t, u) -> t.add(u.getAmount()),
+                    BigDecimal::add);
+    order.setTotalValueOfOrder(totalValueOfOrder.toPlainString());
+ }
+}