Java: use Objects.hashCode() for single field JDK7+ hashCode() generation (IDEA-177907)

GitOrigin-RevId: 59011b448a85df06ef0b1a5960ab3bf7c77bc32f

java/java-impl/src/com/intellij/codeInsight/generation/objectsHashCode.vm

@@ -1,6 +1,10 @@
 public int hashCode() {
-#if (!$superHasHashCode && $fields.size()==1 && $fields[0].array)
-  return java.util.Arrays.hashCode($fields[0].accessor);
+#if (!$superHasHashCode && $fields.size()==1)
+  #if ($fields[0].array)
+    return java.util.Arrays.hashCode($fields[0].accessor);
+  #else
+    return java.util.Objects.hashCode($fields[0].accessor);
+  #end
 #else
   #set($hasArrays = false)
   #set($hasNoArrays = false)
@@ -20,7 +24,7 @@ public int hashCode() {
       #end
       #foreach($field in $fields)
         #if ($i > 0)
-        , ##
+          , ##
         #end
         $field.accessor ##
         #set($i = $i + 1)
@@ -41,7 +45,7 @@ public int hashCode() {
         #foreach($field in $fields)
           #if(!$field.array)
             #if ($i > 0)
-            , ##
+              , ##
             #end
             $field.accessor ##
             #set($i = $i + 1)
@@ -60,7 +64,7 @@ public int hashCode() {
         #if ($resultDeclarationCompleted)
           $resultName ##
         #end
-        = ##
+          = ##
         #if ($resultAssigned)
           31 * $resultName + ##
         #end

java/java-tests/testData/codeInsight/completion/normal/InvokeGenerateEqualsHashCodeOnOverrideCompletion_after.java

@@ -13,6 +13,6 @@ class A {
 
     @Override
     public int hashCode() {
-        return Objects.hash(a);
+        return Objects.hashCode(a);
     }
 }

java/java-tests/testData/codeInsight/generateEquals/afterSingleFieldWithObjectsTemplate.java

@@ -0,0 +1,18 @@
+import java.util.Objects;
+
+class X {
+  private String s = null;
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        final X x = (X) o;
+        return Objects.equals(s, x.s);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(s);
+    }
+}

java/java-tests/testData/codeInsight/generateEquals/beforeSingleFieldWithObjectsTemplate.java

@@ -0,0 +1,3 @@
+class X {
+  private String s = null;
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/GenerateEqualsTest.java

@@ -134,6 +134,10 @@ public class GenerateEqualsTest extends LightJavaCodeInsightTestCase {
     doTestWithTemplate(EqualsHashCodeTemplatesManager.JAVA_UTIL_OBJECTS_EQUALS_AND_HASH_CODE);
   }
 
+  public void testSingleFieldWithObjectsTemplate() {
+    doTestWithTemplate(EqualsHashCodeTemplatesManager.JAVA_UTIL_OBJECTS_EQUALS_AND_HASH_CODE);
+  }
+
   public void testArrayAndNotOnlyArrayWithObjectsTemplate() {
     doTestWithTemplate(EqualsHashCodeTemplatesManager.JAVA_UTIL_OBJECTS_EQUALS_AND_HASH_CODE);
   }