Invert if statements with negated conditions. #1555

Fixes `NegatedIfElse` inspection violations.

Description:
>Reports if statements which contain else branches and whose conditions are negated. Flipping the order of the if and else branches will usually increase the clarity of such statements.

src/main/java/com/puppycrawl/tools/checkstyle/Main.java

@@ -82,20 +82,20 @@ public final class Main {
                 // return error is smth is wrong in arguments
                 final List<String> messages = validateCli(commandLine);
                 cliViolations = !messages.isEmpty();
-                if (!cliViolations) {
-                    // create config helper object
-                    final CliOptions config = convertCliToPojo(commandLine);
-                    // run Checker
-                    errorCounter = runCheckstyle(config);
-                    exitStatus = errorCounter;
-                }
-                else {
+                if (cliViolations) {
                     exitStatus = exitWithCliViolation;
                     errorCounter = 1;
                     for (String message : messages) {
                         System.out.println(message);
                     }
                 }
+                else {
+                    // create config helper object
+                    final CliOptions config = convertCliToPojo(commandLine);
+                    // run Checker
+                    errorCounter = runCheckstyle(config);
+                    exitStatus = errorCounter;
+                }
             }
         }
         catch (ParseException pex) {
@@ -147,10 +147,7 @@ public final class Main {
     private static List<String> validateCli(CommandLine cmdLine) {
         final List<String> result = new ArrayList<>();
         // ensure a configuration file is specified
-        if (!cmdLine.hasOption("c")) {
-            result.add("Must specify a config XML file.");
-        }
-        else {
+        if (cmdLine.hasOption("c")) {
             // validate optional parameters
             if (cmdLine.hasOption("f")) {
                 final String format = cmdLine.getOptionValue("f");
@@ -178,6 +175,9 @@ public final class Main {
                 result.add("Must specify files to process, found 0.");
             }
         }
+        else {
+            result.add("Must specify a config XML file.");
+        }
 
         return result;
     }

src/main/java/com/puppycrawl/tools/checkstyle/TreeWalker.java

@@ -250,7 +250,10 @@ public final class TreeWalker
         throws CheckstyleException {
         final int[] tokens;
         final Set<String> checkTokens = check.getTokenNames();
-        if (!checkTokens.isEmpty()) {
+        if (checkTokens.isEmpty()) {
+            tokens = check.getDefaultTokens();
+        }
+        else {
             tokens = check.getRequiredTokens();
 
             //register configured tokens
@@ -268,9 +271,6 @@ public final class TreeWalker
                 }
             }
         }
-        else {
-            tokens = check.getDefaultTokens();
-        }
         for (int element : tokens) {
             registerCheck(element, check);
         }

src/main/java/com/puppycrawl/tools/checkstyle/checks/OuterTypeFilenameCheck.java

@@ -74,7 +74,14 @@ public class OuterTypeFilenameCheck extends Check {
     @Override
     public void visitToken(DetailAST ast) {
         final String outerTypeName = ast.findFirstToken(TokenTypes.IDENT).getText();
-        if (!seenFirstToken) {
+        if (seenFirstToken) {
+            final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
+            if (modifiers.findFirstToken(TokenTypes.LITERAL_PUBLIC) != null
+                    && ast.getParent() == null) {
+                hasPublic = true;
+            }
+        }
+        else {
 
             if (fileName.equals(outerTypeName)) {
                 validFirst = true;
@@ -83,13 +90,6 @@ public class OuterTypeFilenameCheck extends Check {
                 wrongType = ast;
             }
         }
-        else {
-            final DetailAST modifiers = ast.findFirstToken(TokenTypes.MODIFIERS);
-            if (modifiers.findFirstToken(TokenTypes.LITERAL_PUBLIC) != null
-                    && ast.getParent() == null) {
-                hasPublic = true;
-            }
-        }
         seenFirstToken = true;
     }
 

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

@@ -142,11 +142,11 @@ public class FallThroughCheck extends Check {
 
         if (slist != null && !isTerminated(slist, true, true)
             && !hasFallTruComment(ast, nextGroup)) {
-            if (!isLastGroup) {
-                log(nextGroup, MSG_FALL_THROUGH);
+            if (isLastGroup) {
+                log(ast, MSG_FALL_THROUGH_LAST);
             }
             else {
-                log(ast, MSG_FALL_THROUGH_LAST);
+                log(nextGroup, MSG_FALL_THROUGH);
             }
         }
     }

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

@@ -243,12 +243,12 @@ public class InnerAssignmentCheck
             for (int anElement : element) {
                 current = current.getParent();
                 final int expectedType = anElement;
-                if (current.getType() != expectedType) {
-                    found = false;
-                    break;
+                if (current.getType() == expectedType) {
+                    found = true;
                 }
                 else {
-                    found = true;
+                    found = false;
+                    break;
                 }
             }
 

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

@@ -342,11 +342,11 @@ public class VariableDeclarationUsageDistanceCheck extends Check {
                         }
                         // differs from previous instance
                         else if (!instanceName.equals(initInstanceName)) {
-                            if (!initInstanceName.isEmpty()) {
-                                result = false;
+                            if (initInstanceName.isEmpty()) {
+                                initInstanceName = instanceName;
                             }
                             else {
-                                initInstanceName = instanceName;
+                                result = false;
                             }
                         }
                     }

src/main/java/com/puppycrawl/tools/checkstyle/checks/indentation/MemberDefHandler.java

@@ -44,11 +44,11 @@ public class MemberDefHandler extends AbstractExpressionHandler {
     @Override
     public void checkIndentation() {
         final DetailAST modifiersNode = getMainAst().findFirstToken(TokenTypes.MODIFIERS);
-        if (modifiersNode.getChildCount() != 0) {
-            checkModifiers();
+        if (modifiersNode.getChildCount() == 0) {
+            checkType();
         }
         else {
-            checkType();
+            checkModifiers();
         }
         final LineWrappingHandler lineWrap =
             new LineWrappingHandler(getIndentCheck(), getMainAst(),

src/main/java/com/puppycrawl/tools/checkstyle/checks/javadoc/JavadocStyleCheck.java

@@ -365,13 +365,7 @@ public class JavadocStyleCheck
                 //do nothing
                 continue;
             }
-            if (!tag.isCloseTag()) {
-                //We only push html tags that are allowed
-                if (isAllowedTag(tag)) {
-                    htmlStack.push(tag);
-                }
-            }
-            else {
+            if (tag.isCloseTag()) {
                 // We have found a close tag.
                 if (isExtraHtml(tag.getId(), htmlStack)) {
                     // No corresponding open tag was found on the stack.
@@ -386,6 +380,12 @@ public class JavadocStyleCheck
                     checkUnclosedTags(htmlStack, tag.getId());
                 }
             }
+            else {
+                //We only push html tags that are allowed
+                if (isAllowedTag(tag)) {
+                    htmlStack.push(tag);
+                }
+            }
         }
 
         // Identify any tags left on the stack.

src/main/java/com/puppycrawl/tools/checkstyle/checks/javadoc/JavadocUtils.java

@@ -130,14 +130,14 @@ public final class JavadocUtils {
                 final Matcher commentMatcher = commentPattern.matcher(s);
                 final String commentContents;
                 final int commentOffset; // offset including comment characters
-                if (!commentMatcher.find()) {
-                    commentContents = s; // No leading asterisks, still valid
-                    commentOffset = 0;
-                }
-                else {
+                if (commentMatcher.find()) {
                     commentContents = commentMatcher.group(1);
                     commentOffset = commentMatcher.start(1) - 1;
                 }
+                else {
+                    commentContents = s; // No leading asterisks, still valid
+                    commentOffset = 0;
+                }
                 final Pattern tagPattern = Pattern.compile(".*?\\{@(\\p{Alpha}+)\\s+(.*?)\\}");
                 final Matcher tagMatcher = tagPattern.matcher(commentContents);
                 while (tagMatcher.find()) {

src/main/java/com/puppycrawl/tools/checkstyle/checks/regexp/MultilineDetector.java

@@ -79,14 +79,14 @@ class MultilineDetector {
         this.text = new FileText(text);
         resetState();
 
-        if (!Strings.isNullOrEmpty(options.getFormat())) {
+        if (Strings.isNullOrEmpty(options.getFormat())) {
+            options.getReporter().log(0, EMPTY);
+        }
+        else {
             matcher = options.getPattern().matcher(text.getFullText());
             findMatch();
             finish();
         }
-        else {
-            options.getReporter().log(0, EMPTY);
-        }
     }
 
     /** Method that finds the matches. */