Avoid Collections#sort

With the introduction of default methods in Java 8, Java finally grew a
List#sort method that can be used in place of the static
Collections#sort. Convert simple in-place sorts that need to be in-place
sorts to use this method where possible.

During the course of this change, it became obvious that many instances
of sort were just sorting a newly-created ArrayList in place. These can
be replaced with more idiomatic Stream constructions, sometimes even
eliminating a loop to populate the list.

One difference between List#sort and Collections#sort is there is no
List#sort() with no arguments; callers must always pass either
naturalOrder() or a null comparators. In this change, there were so few
remaining instances of sorting by natural order that typing
naturalOrder() didn't seem too repetitious, and it is quite readable.

Change-Id: I4d89421a72127e9a36cbd32aeac425c0471a1b3f

3 files changed, 6 insertions, 12 deletions

diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
index 3587bf8519..0f786a6d66 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
@@ -32,7 +32,6 @@ import com.google.gwt.core.client.JsArrayString;
 import com.google.gwtjsonrpc.client.impl.ser.JavaSqlTimestamp_JsonSerializer;
 import java.sql.Timestamp;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -448,9 +447,8 @@ public class ChangeInfo extends JavaScriptObject {
 
     public static void sortRevisionInfoByNumber(JsArray<RevisionInfo> list) {
       final int editParent = findEditParent(list);
-      Collections.sort(
-          Natives.asList(list),
-          comparing(r -> !r.isEdit() ? 2 * (r._number() - 1) + 1 : 2 * editParent));
+      Natives.asList(list)
+          .sort(comparing(r -> !r.isEdit() ? 2 * (r._number() - 1) + 1 : 2 * editParent));
     }
 
     public static int findEditParent(JsArray<RevisionInfo> list) {
diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
index 345a260cee..fc3dbf1b04 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
@@ -19,7 +19,6 @@ import com.google.gerrit.common.data.FilenameComparator;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
-import java.util.Collections;
 import java.util.Comparator;
 
 public class FileInfo extends JavaScriptObject {
@@ -55,8 +54,7 @@ public class FileInfo extends JavaScriptObject {
   public final native void _row(int r) /*-{ this._row = r }-*/;
 
   public static void sortFileInfoByPath(JsArray<FileInfo> list) {
-    Collections.sort(
-        Natives.asList(list), Comparator.comparing(FileInfo::path, FilenameComparator.INSTANCE));
+    Natives.asList(list).sort(Comparator.comparing(FileInfo::path, FilenameComparator.INSTANCE));
   }
 
   public static String getFileName(String path) {
diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
index 4b170687c9..41306ff2fd 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
@@ -14,11 +14,12 @@
 
 package com.google.gerrit.client.rpc;
 
+import static java.util.stream.Collectors.toCollection;
+
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.user.client.rpc.AsyncCallback;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
@@ -57,10 +58,7 @@ public class NativeMap<T extends JavaScriptObject> extends JavaScriptObject {
   }
 
   public final List<String> sortedKeys() {
-    Set<String> keys = keySet();
-    List<String> sorted = new ArrayList<>(keys);
-    Collections.sort(sorted);
-    return sorted;
+    return keySet().stream().sorted().collect(toCollection(ArrayList::new));
   }
 
   public final native JsArray<T> values() /*-{