How do I calculate the time between frames on Android? I'm using this for the thread:

public class GameThread extends Thread
  private int FPS = 30;
  private double averageFPS;
  private SurfaceHolder surfaceHolder;
  private Game gamePanel;
  public boolean running;
  public static Canvas canvas;
  public static double deltaTime;

  public GameThread(SurfaceHolder surfaceHolder, Game gamePanel) {
    this.surfaceHolder = surfaceHolder;
    this.gamePanel = gamePanel;

  public void run() {
    long startTime;
    long timeMillis;
    long waitTime;
    long totalTime = 0;
    int frameCount =0;
    long targetTime = 1000/FPS;

    while(running) {
      startTime = System.nanoTime();
      canvas = null;

      //try locking the canvas for pixel editing
      try {
        canvas = this.surfaceHolder.lockCanvas();
        synchronized (surfaceHolder) {
      } catch (Exception e) {
      } finally {
          try {
          } catch(Exception e){

      timeMillis = (System.nanoTime() - startTime) / 1000000;
      waitTime = targetTime-timeMillis;

      } catch (Exception e) {

      deltaTime = waitTime;
      totalTime += System.nanoTime() - startTime;
      if(frameCount == FPS)
        averageFPS = 1000/((totalTime/frameCount)/1000000);
        frameCount =0;
        totalTime = 0;

  public void setRunning(boolean b)

I tried doing it like in normal Java, but it didn't work (it only lead to a crash).


closed as off-topic by Vaillancourt, Engineer, Anko, Kromster says support Monica, Josh Nov 19 '15 at 17:38

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  • \$\begingroup\$ "but it didn't work (it only lead to a crash)" is not helpful at all for us to help you. Where does it crash? At what line? What's the error message? \$\endgroup\$ – Vaillancourt Nov 14 '15 at 13:26
  • \$\begingroup\$ It lead to a chrash in a array list. It was a nullpointer exception \$\endgroup\$ – user69046 Nov 14 '15 at 16:03
  • 1
    \$\begingroup\$ It's still unclear what you're asking. You do not specify what line causes the crash. Most of your code is within try-catch blocks so the exception would not pop out from the core of your code... \$\endgroup\$ – Vaillancourt Nov 14 '15 at 16:08
  • \$\begingroup\$ I used a completly different system which i speed translated to android. What i want is a way to calculate delta time on anroid \$\endgroup\$ – user69046 Nov 14 '15 at 19:14