IDEA-192382 Override unused imports when adding class with same name

java/java-impl/src/com/intellij/psi/impl/source/codeStyle/ImportHelper.java

@@ -430,6 +430,7 @@ public class ImportHelper{
     String packageName = getPackageOrClassName(className);
     String shortName = PsiNameHelper.getShortClassName(className);
 
+    findUnusedSingleImport(file, shortName).ifPresent(PsiElement::delete);
     PsiClass conflictSingleRef = findSingleImportByShortName(file, shortName);
     if (conflictSingleRef != null && !forceReimport){
       return className.equals(conflictSingleRef.getQualifiedName());
@@ -522,6 +523,25 @@ public class ImportHelper{
     return true;
   }
 
+  private static Optional<PsiImportStatement> findUnusedSingleImport(PsiJavaFile file, String name) {
+    PsiImportList importList = file.getImportList();
+    if (importList != null) {
+      for (PsiImportStatement statement : importList.getImportStatements()) {
+        PsiJavaCodeReferenceElement ref = statement.getImportReference();
+        if (!statement.isOnDemand() && ref != null && name.equals(ref.getReferenceName())) {
+          PsiElement target = statement.resolve();
+          if (target instanceof PsiClass) {
+            Collection<PsiReference> all = ReferencesSearch.search(target, new LocalSearchScope(file)).findAll();
+            if (all.size() == 1 && PsiTreeUtil.isAncestor(statement, all.iterator().next().getElement(), true)) {
+              return Optional.of(statement);
+            }
+          }
+        }
+      }
+    }
+    return Optional.empty();
+  }
+
   private static boolean containsInCurrentPackage(@NotNull PsiJavaFile file, PsiClass curRefClass) {
     if (curRefClass != null) {
       final String curRefClassQualifiedName = curRefClass.getQualifiedName();

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

@@ -0,0 +1,5 @@
+import foo.List;
+
+class Scratch {
+  Lis<caret>
+}

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

@@ -0,0 +1,5 @@
+import java.util.List;
+
+class Scratch {
+  List<caret>
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionTest.groovy

@@ -1859,4 +1859,12 @@ class Bar {{
     checkResult()
   }
 
+  void testRemoveUnusedImportOfSameName() {
+    myFixture.addClass("package foo; public class List {}")
+    configureByTestName()
+    lookup.currentItem = myFixture.lookupElements.find { it.object instanceof PsiClass && ((PsiClass)it.object).qualifiedName == 'java.util.List' }
+    myFixture.type('\n')
+    checkResult()
+  }
+
 }