prefer expected type generics suggestions in java completion, overwrite existing type arguments (IDEA-145119)

java/java-impl/src/com/intellij/codeInsight/completion/PreferByKindWeigher.java

@@ -150,6 +150,7 @@ public class PreferByKindWeigher extends LookupElementWeigher {
     superMethodParameters,
     field,
     expectedTypeConstant,
+    expectedTypeArgument,
     getter,
     normal,
     collectionFactory,
@@ -208,6 +209,9 @@ public class PreferByKindWeigher extends LookupElementWeigher {
     if (expectedTypeMember != null) {
       return expectedTypeMember ? (object instanceof PsiField ? MyResult.expectedTypeConstant : MyResult.expectedTypeMethod) : MyResult.classNameOrGlobalStatic;
     }
+    if (item instanceof TypeArgumentCompletionProvider.TypeArgsLookupElement) {
+      return MyResult.expectedTypeArgument;
+    }
     final JavaChainLookupElement chain = item.as(JavaChainLookupElement.CLASS_CONDITION_KEY);
     if (chain != null) {
       Object qualifier = chain.getQualifier().getObject();

java/java-impl/src/com/intellij/codeInsight/completion/TypeArgumentCompletionProvider.java

@@ -94,7 +94,6 @@ class TypeArgumentCompletionProvider extends CompletionProvider<CompletionParame
     final PsiClass expectedClass = expectedType.getElement();
 
     if (!InheritanceUtil.isInheritorOrSelf(actualClass, expectedClass, true)) return;
-    assert expectedClass != null;
 
     final PsiSubstitutor currentSubstitutor = TypeConversionUtil.getClassSubstitutor(expectedClass, actualClass, PsiSubstitutor.EMPTY);
     assert currentSubstitutor != null;
@@ -246,7 +245,15 @@ class TypeArgumentCompletionProvider extends CompletionProvider<CompletionParame
 
     @Override
     public void handleInsert(InsertionContext context) {
-      context.getDocument().deleteString(context.getStartOffset(), context.getTailOffset());
+      context.commitDocument();
+      PsiReferenceParameterList list = PsiTreeUtil.findElementOfClassAtOffset(context.getFile(), context.getStartOffset(), PsiReferenceParameterList.class, false);
+      PsiTypeElement[] typeElements = list != null ? list.getTypeParameterElements() : PsiTypeElement.EMPTY_ARRAY;
+      if (typeElements.length == 0) {
+        return;
+      }
+      int listEnd = typeElements[typeElements.length - 1].getTextRange().getEndOffset();
+      context.setTailOffset(listEnd);
+      context.getDocument().deleteString(context.getStartOffset(), listEnd);
       for (int i = 0; i < myTypeItems.size(); i++) {
         PsiTypeLookupItem typeItem = myTypeItems.get(i);
         CompletionUtil.emulateInsertion(context, context.getTailOffset(), typeItem);

java/java-tests/testData/codeInsight/completion/smartType/TypeArgsOverwrite-out.java

@@ -0,0 +1,9 @@
+import java.util.*;
+
+class Foo {
+
+    void bar() {
+        Map<Integer, String> a = new HashMap<Integer, String>(<caret>);
+    }
+
+}

java/java-tests/testData/codeInsight/completion/smartType/TypeArgsOverwrite.java

@@ -0,0 +1,9 @@
+import java.util.*;
+
+class Foo {
+
+    void bar() {
+        Map<Integer, String> a = new HashMap<<caret>, String>();
+    }
+
+}

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

@@ -1324,8 +1324,7 @@ class XInternalError {}
 
   public void testSuggestAllTypeArguments() {
     configure()
-    assert 'String, String' == lookup.items[1].lookupString
-    lookup.currentItem = lookup.items[1]
+    assert 'String, String' == lookup.items[0].lookupString
     type '\n'
     checkResult()
   }

java/java-tests/testSrc/com/intellij/codeInsight/completion/SmartTypeCompletionTest.java

@@ -909,6 +909,7 @@ public class SmartTypeCompletionTest extends LightFixtureCompletionTestCase {
   public void testTypeArgs2() throws Exception {
     doTest();
   }
+  public void testTypeArgsOverwrite() { doTest(); }
 
   public void testIfConditionExpectedType() throws Exception { doTest(); }