code: public void update ()
      {
          // grab the various system properties
          osName = System.getProperty("os.name");
          osVersion = System.getProperty("os.version");
          osArch = System.getProperty("os.arch");
          javaVersion = System.getProperty("java.version");
          javaVendor = System.getProperty("java.vendor");
  
          // determine memory usage
          Runtime rtime = Runtime.getRuntime();
          freeMemory = rtime.freeMemory() / 1024;
          totalMemory = rtime.totalMemory() / 1024;
          usedMemory = totalMemory - freeMemory;
          maxMemory = rtime.maxMemory() / 1024;
  
          // determine video display information
          isHeadless = GraphicsEnvironment.isHeadless();
          if (!isHeadless) {
              try {
                  GraphicsEnvironment env =
                      GraphicsEnvironment.getLocalGraphicsEnvironment();
                  GraphicsDevice gd = env.getDefaultScreenDevice();
                  DisplayMode mode = gd.getDisplayMode();
                  bitDepth = mode.getBitDepth();
                  refreshRate = mode.getRefreshRate() / 1024;
                  isFullScreen = (gd.getFullScreenWindow() != null);
                  displayWidth = mode.getWidth();
                  displayHeight = mode.getHeight();
  
              } catch (Throwable t) {
                  isHeadless = true;
              }
          }
      }
docs: Updates the system info record's statistics to reflect the current
  state of the JVM.