IDEA-195573 Support collectingAndThen in Stream-to-loop (for now only if downstream is collection-based)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamToLoop/afterCollectingAndThen.java

@@ -0,0 +1,51 @@
+// "Fix all 'Stream API call chain can be replaced with loop' problems in file" "true"
+
+import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class Main {
+  void sample(List<String> people) {
+      // comment
+      List<String> list = new ArrayList<>();
+      for (String person : people) {
+          list.add(person);
+      }
+      List<String> list1 = Collections.unmodifiableList(list);
+  }
+
+  void sample1(List<String> people) {
+
+      // comment
+      List<String> list = new ArrayList<>();
+      for (String person : people) {
+          list.add(person);
+      }
+      List<String> listIdentity = list;
+  }
+
+  void sample2(List<String> people) {
+      // comment
+      Map<Integer, String> result = new HashMap<>();
+      for (String person : people) {
+          if (result.put(person.length(), person) != null) {
+              throw new IllegalStateException("Duplicate key");
+          }
+      }
+      Map<Integer, String> map = Collections.unmodifiableMap(result);
+  }
+
+  void sample3(List<String> people) {
+    List<String> list2 = people.stream().collect( // comment
+      Collectors.collectingAndThen(Collectors.<String, List<String>>toCollection(LinkedList::new),
+        list -> {
+            List<String> result = new ArrayList<>();
+            for (Iterator<String> it = Stream.concat(list.stream(), list.stream()).iterator(); it.hasNext(); ) {
+                String s = it.next();
+                result.add(s);
+            }
+            return result;
+        }));
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamToLoop/beforeCollectingAndThen.java

@@ -0,0 +1,33 @@
+// "Fix all 'Stream API call chain can be replaced with loop' problems in file" "true"
+
+import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class Main {
+  void sample(List<String> people) {
+    List<String> list1 = people.stream().coll<caret>ect( // comment
+                                                         Collectors.collectingAndThen(Collectors.toList(),
+                                                                                      Collections::unmodifiableList));
+  }
+
+  void sample1(List<String> people) {
+
+    List<String> listIdentity = people.stream().collect( // comment
+                                                         Collectors.collectingAndThen(Collectors.toList(),
+                                                                                      Function.identity()));
+  }
+
+  void sample2(List<String> people) {
+    Map<Integer, String> map = people.stream().collect( // comment
+                                                        Collectors.collectingAndThen(Collectors.toMap(String::length, Function.identity()),
+                                                                                     Collections::unmodifiableMap));
+  }
+
+  void sample3(List<String> people) {
+    List<String> list2 = people.stream().collect( // comment
+      Collectors.collectingAndThen(Collectors.<String, List<String>>toCollection(LinkedList::new),
+        list -> Stream.concat(list.stream(), list.stream()).collect(Collectors.toList())));
+  }
+}