How to run indexing in code

I wanna run "gradle jar" and refresh this jar in code

2017-7-11 update: I find more simple way to run indexing

DumbServiceImpl dumbService = DumbServiceImpl.getInstance(pj2);
DumbModeTask task = FileBasedIndexProjectHandler.createChangedFilesIndexingTask(pj2);
if (task != null) {
    dumbService.queueTask(task);
} //                            RefreshUtil.forceRefreshFiles()

2016-4-21 update: If following ways all don't work, the simple way to reindexing is reopen current project

void restartCurProject() {
    String pjRt2 = getPjRt()
    app.invokeLater(new Runnable() {
        @Override
        void run() {
            ProjectUtil.closeAndDispose(pj)
            ProjectUtil.openProject(pjRt2, pj, true)
        }
    })
}

2016-4-20 update: I find a better way, in following code, I can force specific what files should be indexed

    interface RunBeforeRefresh {
        void run()
        ArrayList<String> getFiles()
    }

    static void forceRefreshFiles(Act act, RunBeforeRefresh runBeforeRefresh) {
        Project pj = act.pj
        final FileBasedIndexImpl index = FileBasedIndexImpl.instance;

        DumbModeTask refreshTask = new DumbModeTask(pj.getComponent(FileBasedIndexProjectHandler.class)) {
            @Override
            void performInDumbMode(@NotNull ProgressIndicator indicator) {
                runBeforeRefresh.run()
                ArrayList<String> files = runBeforeRefresh.files

                final Collection<VirtualFile> files2 = files.collect {
                   act.getVirtualFile(it)
                }
                indicator.setIndeterminate(false);
                indicator.setText(IdeBundle.message("progress.indexing.updating"));
                CacheUpdateRunner.processFiles(indicator, true, files2, pj, new Consumer<FileContent>() {
                    @Override
                    void consume(FileContent ctn) {
                        index.processRefreshedFile(pj, ctn)
                    }
                })
            }
        }

//        if (refreshTask != null) {
//            dumbService.queueTask(refreshTask);
//        }

//        ProgressManager.instance.run(t)
        DumbServiceImpl.getInstance(pj).queueTask(refreshTask)
    }

I fix my question, here is "synchronized" action code:

public class SynchronizeAction extends AnAction implements DumbAware {
  @Override
  public void actionPerformed(AnActionEvent e) {
    FileDocumentManager.getInstance().saveAllDocuments();
    SaveAndSyncHandler.getInstance().refreshOpenFiles();
    VirtualFileManager.getInstance().refreshWithoutFileWatcher(true);
  }
}