convert to atomic: add rule for array.length

java/typeMigration/src/com/intellij/refactoring/typeMigration/rules/AtomicConversionRule.java

@@ -12,6 +12,8 @@ import com.intellij.refactoring.typeMigration.TypeConversionDescriptor;
 import com.intellij.refactoring.typeMigration.TypeConversionDescriptorBase;
 import com.intellij.refactoring.typeMigration.TypeEvaluator;
 import com.intellij.refactoring.typeMigration.TypeMigrationLabeler;
+import com.intellij.util.ObjectUtils;
+import com.siyeh.HardcodedMethodConstants;
 import com.siyeh.ig.psiutils.ParenthesesUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -342,6 +344,9 @@ public class AtomicConversionRule extends TypeConversionRule {
     if (context instanceof PsiArrayAccessExpression) {
       return new TypeConversionDescriptor("$qualifier$[$idx$]", "$qualifier$.get($idx$)", (PsiExpression)context);
     }
+    if (parent instanceof PsiReferenceExpression && isReferenceToLengthField((PsiReferenceExpression)parent)) {
+      return new TypeConversionDescriptor("$qualifier$.length", "$qualifier$.length()", (PsiExpression)parent);
+    }
     return null;
   }
 
@@ -438,4 +443,13 @@ public class AtomicConversionRule extends TypeConversionRule {
     return null;
   }
 
+  private static boolean isReferenceToLengthField(@NotNull PsiReferenceExpression refExpr) {
+    if (!"length".equals(refExpr.getReferenceName())) {
+      return false;
+    }
+    PsiClass aClass = JavaPsiFacade.getElementFactory(refExpr.getProject()).getArrayClass(PsiUtil.getLanguageLevel(refExpr));
+    PsiField lengthField = ObjectUtils.notNull(aClass.findFieldByName(HardcodedMethodConstants.LENGTH, false));
+    return refExpr.isReferenceTo(lengthField);
+  }
+
 }

java/typeMigration/testData/intentions/atomic/afterAtomicArrayLength.java

@@ -0,0 +1,10 @@
+import java.util.concurrent.atomic.AtomicIntegerArray;
+
+// "Convert to atomic" "true"
+class Test {
+  final AtomicIntegerArray ii = new AtomicIntegerArray(new int[12]);
+
+  void m() {
+    int k = ii.length();
+  }
+}

java/typeMigration/testData/intentions/atomic/beforeAtomicArrayLength.java

@@ -0,0 +1,8 @@
+// "Convert to atomic" "true"
+class Test {
+  int[] i<caret>i = new int[12];
+
+  void m() {
+    int k = ii.length;
+  }
+}