java 1.8, stream api migration: convert to method refs

java/java-analysis-impl/src/com/intellij/codeInspection/StreamApiMigrationInspection.java

@@ -261,7 +261,17 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
               iteration += ".filter(" + parameter.getName() + " -> " + condition.getText() +")";
             }
           }
-          iteration +=".map(" + parameter.getName() + " -> " + methodCallExpression.getArgumentList().getExpressions()[0].getText() + ").collect(java.util.stream.Collectors.";
+          iteration +=".map(";
+
+          final PsiExpression mapperCall = methodCallExpression.getArgumentList().getExpressions()[0];
+
+          final String methodReferenceText = LambdaCanBeMethodReferenceInspection.createMethodReferenceText(mapperCall, null, new PsiParameter[]{parameter});
+          if (methodReferenceText != null) {
+            iteration += methodReferenceText;
+          } else {
+            iteration += parameter.getName() + " -> " + mapperCall.getText();
+          }
+          iteration += ").collect(java.util.stream.Collectors.";
 
           String variableName = null;
           PsiExpression initializer = null;

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectArrayList.java

@@ -10,6 +10,6 @@ public class Collect {
   }
 
   void collectNames(List<Person> persons){
-    List<String> names = persons.stream().map(person -> person.getName()).collect(Collectors.toList());
+    List<String> names = persons.stream().map(person::getName).collect(Collectors.toList());
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectArrayListAndFilter.java

@@ -10,6 +10,6 @@ public class Collect {
   }
 
   void collectNames(List<Person> persons){
-    List<String> names = persons.stream().filter(person -> person != null).map(person -> person.getName()).collect(Collectors.toList());
+    List<String> names = persons.stream().filter(person -> person != null).map(person::getName).collect(Collectors.toList());
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectArrayListLambda.java

@@ -0,0 +1,15 @@
+// "Replace with collect" "true"
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class Collect {
+  class Person {
+    String getName() {
+      return "";
+    }
+  }
+
+  void collectNames(List<Person> persons){
+    List<String> names = persons.stream().map(person -> "name: " + person.getName()).collect(Collectors.toList());
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectHashSet.java

@@ -10,6 +10,6 @@ public class Collect {
   }
 
   void collectNames(List<Person> persons){
-    Set<String> names = persons.stream().map(person -> person.getName()).collect(Collectors.toSet());
+    Set<String> names = persons.stream().map(person::getName).collect(Collectors.toSet());
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectHashSetFieldInitializer.java

@@ -11,6 +11,6 @@ public class Collect {
 
   Set<String> names = new HashSet<>();
   void collectNames(List<Person> persons){
-      names.addAll(persons.stream().map(person -> person.getName()).collect(Collectors.toList()));
+      names.addAll(persons.stream().map(person::getName).collect(Collectors.toList()));
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectLinkedHashSet.java

@@ -10,6 +10,6 @@ public class Collect {
   }
 
   void collectNames(List<Person> persons){
-    Set<String> names = persons.stream().map(person -> person.getName()).collect(Collectors.toCollection(() -> new LinkedHashSet<>()));
+    Set<String> names = persons.stream().map(person::getName).collect(Collectors.toCollection(() -> new LinkedHashSet<>()));
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectSelfCollection.java

@@ -10,6 +10,6 @@ public abstract class Collect implements Collection<String>{
   }
 
   void collectNames(List<Person> persons){
-      addAll(persons.stream().map(person -> person.getName()).collect(Collectors.toList()));
+      addAll(persons.stream().map(person::getName).collect(Collectors.toList()));
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/afterCollectSetParameter.java

@@ -10,6 +10,6 @@ public class Collect {
   }
 
   void collectNames(List<Person> persons, Set<String> names){
-      names.addAll(persons.stream().map(person -> person.getName()).collect(Collectors.toList()));
+      names.addAll(persons.stream().map(person::getName).collect(Collectors.toList()));
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/beforeCollectArrayListLambda.java

@@ -0,0 +1,17 @@
+// "Replace with collect" "true"
+import java.util.*;
+
+public class Collect {
+  class Person {
+    String getName() {
+      return "";
+    }
+  }
+
+  void collectNames(List<Person> persons){
+    List<String> names = new ArrayList<>();
+    for (Person person : pers<caret>ons) {
+      names.add("name: " + person.getName());
+    }
+  }
+}