diff --git a/java-checks/src/main/java/org/sonar/java/checks/ClassWithOnlyStaticMethodsInstantiationCheck.java b/java-checks/src/main/java/org/sonar/java/checks/ClassWithOnlyStaticMethodsInstantiationCheck.java
index 18772feb9e3..163b12d38af 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/ClassWithOnlyStaticMethodsInstantiationCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/ClassWithOnlyStaticMethodsInstantiationCheck.java
@@ -61,8 +61,8 @@ public void visitNode(Tree tree) {
   }
 
   private static boolean instantiateOwnClass(Tree identifier, Symbol.TypeSymbol newClassTypeSymbol) {
-    Type enclosingClassType = JUtils.enclosingClass(identifier).type();
-    return enclosingClassType.equals(newClassTypeSymbol.type());
+    Symbol enclosingClass = JUtils.enclosingClass(identifier);
+    return enclosingClass != null && enclosingClass.type().equals(newClassTypeSymbol.type());
   }
 
   private static boolean hasOnlyStaticMethodsAndFields(Symbol.TypeSymbol newClassTypeSymbol) {
diff --git a/java-checks/src/main/java/org/sonar/java/checks/MathOnFloatCheck.java b/java-checks/src/main/java/org/sonar/java/checks/MathOnFloatCheck.java
index 22fa7586286..b108b9a230c 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/MathOnFloatCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/MathOnFloatCheck.java
@@ -53,7 +53,7 @@ public void visitBinaryExpression(BinaryExpressionTree tree) {
 
   private static boolean withinStringConcatenation(BinaryExpressionTree tree) {
     Tree parent = skipParenthesesUpwards(tree.parent());
-    return parent.is(Tree.Kind.PLUS) && ((BinaryExpressionTree) parent).symbolType().is("java.lang.String");
+    return parent != null && parent.is(Tree.Kind.PLUS) && ((BinaryExpressionTree) parent).symbolType().is("java.lang.String");
   }
 
 }
diff --git a/java-checks/src/main/java/org/sonar/java/checks/ReturnOfBooleanExpressionsCheck.java b/java-checks/src/main/java/org/sonar/java/checks/ReturnOfBooleanExpressionsCheck.java
index 3ab6b83a16e..60056dcc154 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/ReturnOfBooleanExpressionsCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/ReturnOfBooleanExpressionsCheck.java
@@ -129,7 +129,9 @@ private static Optional<MethodInvocationTree> getMethodInvocation(@Nullable Stat
   }
 
   private static boolean areAllSyntacticallyEquivalentExceptBoolean(MethodInvocationTree mit1, MethodInvocationTree mit2) {
-    if (skipParenthesesUpwards(mit1.parent()).kind() != skipParenthesesUpwards(mit2.parent()).kind()) {
+    Tree parent1 = skipParenthesesUpwards(mit1.parent());
+    Tree parent2 = skipParenthesesUpwards(mit2.parent());
+    if (parent1 == null || parent2 == null || parent1.kind() != parent2.kind()) {
       // requires to have on both side a return statement, or on both side an expression statement.
       return false;
     }
diff --git a/java-checks/src/main/java/org/sonar/java/checks/design/BrainMethodCheck.java b/java-checks/src/main/java/org/sonar/java/checks/design/BrainMethodCheck.java
index 31f5a1c50ca..8efe36b6f5f 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/design/BrainMethodCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/design/BrainMethodCheck.java
@@ -121,7 +121,7 @@ public void endOfAnalysis(ModuleScannerContext context) {
       // plus a percentage of total found — but the percentage component is capped at numberOfAdditionalIssuesThreshold.
       numberOfIssuesToReport = numberOfFoundIssuesThreshold
         + Math.min((numberOfIssuesToReport * issuesToReportPercentage) / 100, numberOfAdditionalIssuesThreshold);
-      issuesFound.sort((a, b) -> b.brainScore - a.brainScore);
+      issuesFound.sort((a, b) -> Integer.compare(b.brainScore, a.brainScore));
     }
     var defaultContext = (DefaultModuleScannerContext) context;
     for (int i = 0; i < numberOfIssuesToReport; i++) {
diff --git a/java-checks/src/main/java/org/sonar/java/checks/spring/UsePageableParameterForPagedQueryCheck.java b/java-checks/src/main/java/org/sonar/java/checks/spring/UsePageableParameterForPagedQueryCheck.java
index 71c06b02103..2c38c158745 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/spring/UsePageableParameterForPagedQueryCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/spring/UsePageableParameterForPagedQueryCheck.java
@@ -44,7 +44,7 @@ public List<Tree.Kind> nodesToVisit() {
   public void visitNode(Tree tree) {
     MethodTreeImpl methodTree = (MethodTreeImpl) tree;
     Symbol.TypeSymbol enclosingClass = methodTree.symbol().enclosingClass();
-    if (!enclosingClass.isInterface()) {
+    if (enclosingClass == null || !enclosingClass.isInterface()) {
       return;
     }
     if (isPageableMethod(methodTree, enclosingClass.type()) && !hasPageableParameter(methodTree)) {
diff --git a/java-checks/src/main/java/org/sonar/java/checks/unused/UnusedLocalVariableCheck.java b/java-checks/src/main/java/org/sonar/java/checks/unused/UnusedLocalVariableCheck.java
index 792440673d0..e782cb54e7b 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/unused/UnusedLocalVariableCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/unused/UnusedLocalVariableCheck.java
@@ -113,8 +113,12 @@ private static boolean isRValue(IdentifierTree tree) {
     if (parent instanceof AssignmentExpressionTree assignment) {
       return assignment.variable() != tree;
     }
+    if (parent == null) {
+      return true;
+    }
+    Tree grandParent = parent.parent();
     // Note that an expression statement can't be a parenthesized expression, so we don't need to skip parentheses here
-    return !(parent.is(INCREMENT_KINDS) && parent.parent().is(Tree.Kind.EXPRESSION_STATEMENT));
+    return !(parent.is(INCREMENT_KINDS) && grandParent != null && grandParent.is(Tree.Kind.EXPRESSION_STATEMENT));
   }
 
   private static boolean isProperLocalVariable(VariableTree variable) {
diff --git a/java-frontend/src/main/java/org/sonar/java/classpath/VersionImpl.java b/java-frontend/src/main/java/org/sonar/java/classpath/VersionImpl.java
index 1d6b21c59ba..583f928b92b 100644
--- a/java-frontend/src/main/java/org/sonar/java/classpath/VersionImpl.java
+++ b/java-frontend/src/main/java/org/sonar/java/classpath/VersionImpl.java
@@ -57,14 +57,14 @@ public static VersionImpl parse(String versionString) {
   @Override
   public int compareTo(Version o) {
     if (!Objects.equals(major, o.major())) {
-      return major - o.major();
+      return Integer.compare(major, o.major());
     }
     if (!Objects.equals(minor, o.minor())) {
-      return minor - o.minor();
+      return Integer.compare(minor, o.minor());
     }
     if (!Objects.equals(patch, o.patch())) {
       if (patch == null || o.patch() == null) return 0;
-      return patch - o.patch();
+      return Integer.compare(patch, o.patch());
     }
     return 0;
   }
diff --git a/java-frontend/src/main/java/org/sonar/java/reporting/JavaQuickFix.java b/java-frontend/src/main/java/org/sonar/java/reporting/JavaQuickFix.java
index 0eb45116b60..0596c04d300 100644
--- a/java-frontend/src/main/java/org/sonar/java/reporting/JavaQuickFix.java
+++ b/java-frontend/src/main/java/org/sonar/java/reporting/JavaQuickFix.java
@@ -93,19 +93,19 @@ public int compare(JavaTextEdit a, JavaTextEdit b) {
         AnalyzerMessage.TextSpan first = a.getTextSpan();
         AnalyzerMessage.TextSpan second = b.getTextSpan();
 
-        int result = first.startLine - second.startLine;
+        int result = Integer.compare(first.startLine, second.startLine);
         if (result != 0) {
           return result;
         }
-        result = first.startCharacter - second.startCharacter;
+        result = Integer.compare(first.startCharacter, second.startCharacter);
         if (result != 0) {
           return result;
         }
-        result = first.endLine - second.endLine;
+        result = Integer.compare(first.endLine, second.endLine);
         if (result != 0) {
           return result;
         }
-        return first.endCharacter - second.endCharacter;
+        return Integer.compare(first.endCharacter, second.endCharacter);
       }
     }
   }