Java: Improve the inspection "Multiple occurrences of the same expression" (IDEA-207247)

java/java-impl/src/com/intellij/codeInspection/duplicateExpressions/SideEffectCalculator.java

@@ -145,16 +145,16 @@ class SideEffectCalculator {
     PsiClass psiClass = method.getContainingClass();
     if (psiClass == null) return true;
 
-    if (ClassUtils.isImmutableClass(psiClass) ||
-        MethodUtils.isEquals(method) ||
+    String className = psiClass.getQualifiedName();
+    if (MethodUtils.isEquals(method) ||
         MethodUtils.isHashCode(method) ||
         MethodUtils.isToString(method) ||
         MethodUtils.isCompareTo(method) ||
-        MethodUtils.isComparatorCompare(method)) {
+        MethodUtils.isComparatorCompare(method) ||
+        ClassUtils.isImmutableClass(psiClass) && !JAVA_IO_FILE.equals(className)) { // methods of File have or are sensitive to side effects
       return false;
     }
 
-    String className = psiClass.getQualifiedName();
     if (JAVA_UTIL_OBJECTS.equals(className)) {
       return false;
     }

java/java-tests/testData/inspection/duplicateExpressions/File.java

@@ -0,0 +1,18 @@
+import java.io.*;
+
+class C {
+  void testConstructor(String path) {
+    File a = <weak_warning descr="Multiple occurrences of 'new File(path)'">new File(path)</weak_warning>;
+    File b = <weak_warning descr="Multiple occurrences of 'new File(path)'">new File(path)</weak_warning>;
+  }
+
+  void testMethods(String path) throws IOException {
+    File f = new File(path);
+
+    boolean a = f.createNewFile();
+    boolean b = f.createNewFile();
+
+    boolean c = f.delete();
+    boolean d = f.delete();
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DuplicateExpressionsTest.kt

@@ -34,6 +34,7 @@ class DuplicateExpressionsTest : LightCodeInsightFixtureTestCase() {
   fun testMathRandom() = doTest(1)
   fun testVariable() = doTest(1)
   fun testLambda() = doTest(20)
+  fun testFile() = doTest(1)
 
   private fun doTest(threshold: Int = 50) {
     val oldThreshold = inspection.complexityThreshold