[java-inspections] IDEA-357190 Support JEP477 - Remove unnecessary qualification is not suggested when it can be

- check if class is already imported

GitOrigin-RevId: 11a43bf80302194a4f8b34125de2bb741f1f3bac

java/java-analysis-impl/src/com/siyeh/ig/psiutils/ImportUtils.java

@@ -130,7 +130,8 @@ public final class ImportUtils {
     if (hasExactImportConflict(fqName, file)) {
       return false;
     }
-    if (hasOnDemandImportConflict(fqName, file, true)) {
+    if (hasOnDemandImportConflict(fqName, file, true) && !isAlreadyImported(file, fqName)
+    ) {
       return false;
     }
     if (containsConflictingReference(file, fqName)) {
@@ -142,6 +143,34 @@ public final class ImportUtils {
     return !containsConflictingTypeParameter(fqName, context);
   }
 
+  /**
+   * Checks if the class with the given fully qualified name is already imported in the specified Java file.
+   *
+   * @param file the Java file to check for the import.
+   * @param fullyQualifiedName the fully qualified name of the class to check.
+   * @return true if the class is already imported, false otherwise.
+   */
+  public static boolean isAlreadyImported(@NotNull PsiJavaFile file, @NotNull String fullyQualifiedName) {
+    String className = extractClassName(file, fullyQualifiedName);
+
+    Project project = file.getProject();
+    PsiResolveHelper resolveHelper = PsiResolveHelper.getInstance(project);
+
+    PsiClass psiClass = resolveHelper.resolveReferencedClass(className, file);
+    return psiClass != null && fullyQualifiedName.equals(psiClass.getQualifiedName());
+  }
+
+  private static @NotNull String extractClassName(@NotNull PsiJavaFile file, @NotNull String fullyQualifiedName) {
+    for (PsiClass aClass : file.getClasses()) {
+      String outerClassName = aClass.getQualifiedName();
+      if (outerClassName != null && fullyQualifiedName.startsWith(outerClassName)) {
+        return fullyQualifiedName.substring(outerClassName.lastIndexOf('.') + 1);
+      }
+    }
+
+    return ClassUtil.extractClassName(fullyQualifiedName);
+  }
+
   private static boolean containsConflictingTypeParameter(String fqName, PsiElement context) {
     final String shortName = ClassUtil.extractClassName(fqName);
     PsiElement parent = context.getParent();

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

@@ -9,7 +9,6 @@ import com.intellij.jsp.JspSpiUtil;
 import com.intellij.lang.ASTNode;
 import com.intellij.lang.java.JavaLanguage;
 import com.intellij.openapi.diagnostic.Logger;
-import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Comparing;
 import com.intellij.openapi.util.NlsSafe;
 import com.intellij.openapi.util.Predicates;
@@ -42,6 +41,7 @@ import com.intellij.util.ObjectUtils;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.MultiMap;
 import com.intellij.util.containers.NotNullList;
+import com.siyeh.ig.psiutils.ImportUtils;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
 import one.util.streamex.StreamEx;
@@ -704,25 +704,15 @@ public final class ImportHelper{
       });
   }
 
+  /**
+   * Checks if the class with the given fully qualified name is already imported in the specified Java file.
+   *
+   * @param file the Java file to check for the import.
+   * @param fullyQualifiedName the fully qualified name of the class to check.
+   * @return true if the class is already imported, false otherwise.
+   */
   public static boolean isAlreadyImported(@NotNull PsiJavaFile file, @NotNull String fullyQualifiedName) {
-    String className = extractClassName(file, fullyQualifiedName);
-
-    Project project = file.getProject();
-    PsiResolveHelper resolveHelper = PsiResolveHelper.getInstance(project);
-
-    PsiClass psiClass = resolveHelper.resolveReferencedClass(className, file);
-    return psiClass != null && fullyQualifiedName.equals(psiClass.getQualifiedName());
-  }
-
-  private static @NotNull String extractClassName(@NotNull PsiJavaFile file, @NotNull String fullyQualifiedName) {
-    for (PsiClass aClass : file.getClasses()) {
-      String outerClassName = aClass.getQualifiedName();
-      if (outerClassName != null && fullyQualifiedName.startsWith(outerClassName)) {
-        return fullyQualifiedName.substring(outerClassName.lastIndexOf('.') + 1);
-      }
-    }
-
-    return ClassUtil.extractClassName(fullyQualifiedName);
+    return ImportUtils.isAlreadyImported(file, fullyQualifiedName);
   }
 
   public ASTNode getDefaultAnchor(@NotNull PsiImportList list, @NotNull PsiImportStatementBase statement){

java/java-tests/testData/ig/com/siyeh/igtest/style/unnecessary_fully_qualified_name/AlreadyImported.after.java

@@ -0,0 +1,6 @@
+import p.Date;
+
+public static void main(String[] args) {
+  Date date;
+  date = new Date();
+}

java/java-tests/testData/ig/com/siyeh/igtest/style/unnecessary_fully_qualified_name/AlreadyImported.java

@@ -0,0 +1,6 @@
+import p.Date;
+
+public static void main(String[] args) {
+  <warning descr="Qualifier 'p' is unnecessary and can be removed">p</warning><caret>.Date date;
+  date = new Date();
+}

java/java-tests/testSrc/com/siyeh/ig/fixes/style/UnnecessaryFullyQualifiedNameWithImplicitImportsFixTest.java

@@ -30,6 +30,14 @@ public class UnnecessaryFullyQualifiedNameWithImplicitImportsFixTest extends Lig
     checkQuickFix(InspectionGadgetsBundle.message("unnecessary.fully.qualified.name.remove.quickfix"));
   }
 
+  public void testAlreadyImported() {
+    myFixture.addClass("""
+    package p;
+    public class Date {}""");
+    doTest();
+    checkQuickFix(InspectionGadgetsBundle.message("unnecessary.fully.qualified.name.remove.quickfix"));
+  }
+
   public void testSimpleImportJavaLangWithImplicitClassWithConflict() {
     myFixture.addClass("""
     package p;