code: public void syncState() {
          if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
              mSlider.setPosition(1);
          } else {
              mSlider.setPosition(0);
          }
          if (mDrawerIndicatorEnabled) {
              setActionBarUpIndicator((Drawable) mSlider,
                      mDrawerLayout.isDrawerOpen(GravityCompat.START) ?
                              mCloseDrawerContentDescRes : mOpenDrawerContentDescRes);
          }
      }
docs: Synchronize the state of the drawer indicator/affordance with the linked DrawerLayout.
  <p/>
  <p>This should be called from your <code>Activity</code>'s
  {@link Activity#onPostCreate(android.os.Bundle) onPostCreate} method to synchronize after
  the DrawerLayout's instance state has been restored, and any other time when the state
  may have diverged in such a way that the JToggle was not notified.
  (For example, if you stop forwarding appropriate drawer events for a period of time.)</p>