allow to implement and override default methods in java 8 (IDEA-103180) [roma]

(cherry picked from commit 6fc2a889a092365431b92d7f03b8d2057a82d8be)

java/java-psi-impl/src/com/intellij/codeInsight/generation/OverrideImplementExploreUtil.java

@@ -4,6 +4,7 @@ import com.intellij.codeInsight.MemberImplementorExplorer;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.extensions.Extensions;
 import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.pom.java.LanguageLevel;
 import com.intellij.psi.*;
 import com.intellij.psi.infos.CandidateInfo;
 import com.intellij.psi.util.MethodSignature;
@@ -63,9 +64,9 @@ public class OverrideImplementExploreUtil {
       }
 
       Map<MethodSignature, PsiMethod> map = hisClass.isInterface() || method.hasModifierProperty(PsiModifier.ABSTRACT) ? abstracts : concretes;
-      PsiMethod other = map.get(signature);
-      if (other == null || preferLeftForImplement(method, other)) {
-        map.put(signature, method);
+      fillMap(signature, method, map);
+      if (isDefaultMethod(aClass, method)) {
+        fillMap(signature, method, concretes);
       }
     }
 
@@ -92,6 +93,18 @@ public class OverrideImplementExploreUtil {
     return result;
   }
 
+  private static boolean isDefaultMethod(PsiClass aClass, PsiMethod method) {
+    return method.hasModifierProperty(PsiModifier.DEFAULT) &&
+           PsiUtil.getLanguageLevel(aClass).isAtLeast(LanguageLevel.JDK_1_8);
+  }
+
+  private static void fillMap(HierarchicalMethodSignature signature, PsiMethod method, Map<MethodSignature, PsiMethod> map) {
+    final PsiMethod other = map.get(signature);
+    if (other == null || preferLeftForImplement(method, other)) {
+      map.put(signature, method);
+    }
+  }
+
   public static void collectMethodsToImplement(PsiClass aClass,
                                                Map<MethodSignature, PsiMethod> abstracts,
                                                Map<MethodSignature, PsiMethod> finals,
@@ -103,7 +116,8 @@ public class OverrideImplementExploreUtil {
       PsiMethod concrete = concretes.get(signature);
       if (concrete == null
           || PsiUtil.getAccessLevel(concrete.getModifierList()) < PsiUtil.getAccessLevel(abstractOne.getModifierList())
-          || !abstractOne.getContainingClass().isInterface() && abstractOne.getContainingClass().isInheritor(concrete.getContainingClass(), true)) {
+          || !abstractOne.getContainingClass().isInterface() && abstractOne.getContainingClass().isInheritor(concrete.getContainingClass(), true)
+          || isDefaultMethod(aClass, abstractOne)) {
         if (finals.get(signature) == null) {
           PsiSubstitutor subst = correctSubstitutor(abstractOne, signature.getSubstitutor());
           CandidateInfo info = new CandidateInfo(abstractOne, subst);

java/java-tests/testData/codeInsight/overrideImplement/afterOverrideExtensionMethods.java

@@ -0,0 +1,39 @@
+interface A<T> {
+    default void m(T t) { }
+}
+
+class MyClass<T> implements A<T> {
+    @Override
+    public void m(T t) {
+        <selection>//To change body of implemented methods use File | Settings | File Templates.</selection>
+    }
+
+    public MyClass() {
+        super();    //To change body of overridden methods use File | Settings | File Templates.
+    }
+
+    @Override
+    public int hashCode() {
+        return super.hashCode();    //To change body of overridden methods use File | Settings | File Templates.
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return super.equals(obj);    //To change body of overridden methods use File | Settings | File Templates.
+    }
+
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return super.clone();    //To change body of overridden methods use File | Settings | File Templates.
+    }
+
+    @Override
+    public String toString() {
+        return super.toString();    //To change body of overridden methods use File | Settings | File Templates.
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        super.finalize();    //To change body of overridden methods use File | Settings | File Templates.
+    }
+}

java/java-tests/testData/codeInsight/overrideImplement/beforeOverrideExtensionMethods.java

@@ -0,0 +1,7 @@
+interface A<T> {
+    default void m(T t) { }
+}
+
+class MyClass<T> implements A<T> {
+    <caret>
+}

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

@@ -66,6 +66,7 @@ public class OverrideImplementTest extends LightCodeInsightTestCase {
   public void testResolveTypeParamConflict() { doTest(false); }
 
   public void testImplementExtensionMethods() { doTest8(false, true); }
+  public void testOverrideExtensionMethods() { doTest8(false, false); }
   public void testDoNotImplementExtensionMethods() { doTest8(false, true); }
 
   public void testLongFinalParameterList() {