According to the maintainer of google-java-format (via email), the tool is mature and ready for widespread use.

The main question is whether it produces results that are consistent enough with existing Chromium code.

Well, the first problem is that google-java-format uses a block indentation of +2 spaces, where Chromium style uses +4.

After adjusting for the indentation issue (using sed), the tool produces results that are mostly consistent with existing code. The main downside I see is that the tool adds a significant amount of whitespace (both newlines and increased indentation):
 1. It wraps after "=" in many cases (some cases almost seem like bugs)
 2. When method parameters don't all fit on one line, it puts each param on a separate line (both when declaring a method and when calling it).

I'm OK with (2), especially since that matches C++ style in Chromium, but (1) isn't ideal. Maybe we could get used to it though?

Here are a few representative before/after comparisons from Tab.java:



-        Tab tab = new Tab(
-                INVALID_TAB_ID, parentId, incognito, activity, nativeWindow, type,
-                TabCreationState.FROZEN_FOR_LAZY_LOAD, null);
+        Tab tab =
+                new Tab(
+                        INVALID_TAB_ID,
+                        parentId,
+                        incognito,
+                        activity,
+                        nativeWindow,
+                        type,
+                        TabCreationState.FROZEN_FOR_LAZY_LOAD,
+                        null);



-            getTabModelSelector().openNewTab(loadUrlParams,
-                    TabLaunchType.FROM_LONGPRESS_FOREGROUND, Tab.this, isIncognito());
+            getTabModelSelector()
+                    .openNewTab(
+                            loadUrlParams, TabLaunchType.FROM_LONGPRESS_FOREGROUND, Tab.this, isIncognito());



-            mDefaultThemeColor = mIncognito
-                    ? ApiCompatibilityUtils.getColor(resources, R.color.incognito_primary_color)
-                    : ApiCompatibilityUtils.getColor(resources, R.color.default_primary_color);
+            mDefaultThemeColor =
+                    mIncognito
+                            ? ApiCompatibilityUtils.getColor(resources, R.color.incognito_primary_color)
+                            : ApiCompatibilityUtils.getColor(resources, R.color.default_primary_color);



-            if (otherTab != tab && otherTab.getTabUma() != null
-                    && otherTab.getTabUma().getLastShownTimestamp() > tabLastShow) {
+            if (otherTab != tab
+                    && otherTab.getTabUma() != null
+                    && otherTab.getTabUma().getLastShownTimestamp() > tabLastShow) {


-        mIsTitleDirectionRtl = LocalizationUtils.getFirstStrongCharacterDirection(title)
-                == LocalizationUtils.RIGHT_TO_LEFT;
+        mIsTitleDirectionRtl =
+                LocalizationUtils.getFirstStrongCharacterDirection(title)
+                        == LocalizationUtils.RIGHT_TO_LEFT;



-            int loadType = nativeLoadUrl(mNativeTabAndroid, params.getUrl(),
-                    params.getVerbatimHeaders(), params.getPostData(), params.getTransitionType(),
-                    params.getReferrer() != null ? params.getReferrer().getUrl() : null,
-                    // Policy will be ignored for null referrer url, 0 is just a placeholder.
-                    // TODO(ppi): Should we pass Referrer jobject and add JNI methods to read it
-                    //            from the native?
-                    params.getReferrer() != null ? params.getReferrer().getPolicy() : 0,
-                    params.getIsRendererInitiated(), params.getShouldReplaceCurrentEntry(),
-                    params.getIntentReceivedTimestamp(), params.getHasUserGesture());
+            int loadType =
+                    nativeLoadUrl(
+                            mNativeTabAndroid,
+                            params.getUrl(),
+                            params.getVerbatimHeaders(),
+                            params.getPostData(),
+                            params.getTransitionType(),
+                            params.getReferrer() != null ? params.getReferrer().getUrl() : null,
+                            // Policy will be ignored for null referrer url, 0 is just a placeholder.
+                            // TODO(ppi): Should we pass Referrer jobject and add JNI methods to read it
+                            //            from the native?
+                            params.getReferrer() != null ? params.getReferrer().getPolicy() : 0,
+                            params.getIsRendererInitiated(),
+                            params.getShouldReplaceCurrentEntry(),
+                            params.getIntentReceivedTimestamp(),
+                            params.getHasUserGesture());



-            OnClickListener suggestionAction = new OnClickListener() {
-                @Override
-                public void onClick(View view) {
-                    Activity activity = mWindowAndroid.getActivity().get();
-                    assert activity != null;
-                    HelpAndFeedback.getInstance(activity).show(activity,
-                            activity.getString(R.string.help_context_sad_tab),
-                            Profile.getLastUsedProfile(), null);
-                }
-            };
+            OnClickListener suggestionAction =
+                    new OnClickListener() {
+                        @Override
+                        public void onClick(View view) {
+                            Activity activity = mWindowAndroid.getActivity().get();
+                            assert activity != null;
+                            HelpAndFeedback.getInstance(activity)
+                                    .show(
+                                            activity,
+                                            activity.getString(R.string.help_context_sad_tab),
+                                            Profile.getLastUsedProfile(),
+                                            null);
+                        }
+                    };



-    private native void nativeSetInterceptNavigationDelegate(long nativeTabAndroid,
-            InterceptNavigationDelegate delegate);
+    private native void nativeSetInterceptNavigationDelegate(
+            long nativeTabAndroid, InterceptNavigationDelegate delegate);

Re: 2 space indentation. The --aosp flag will cause the tool to use 4 space indentation, instead of 2. Just what we need :)

Re (1), wrapping after "=" is deliberate. The formatter was designed around the "break at the highest syntactic level" guidance in style guide [1]. It ends up following that rule a bit more closely than most people would when formatting by hand.

I've found that the additional structure often makes the code clearer, but it can take some getting used to.

[1] https://google.github.io/styleguide/javaguide.html#s4.5.1-line-wrapping-where-to-break

Archiving issues older than 2 years with no owner or component.