how to set a max fps in java

Question

I was making a 2D game, and I realized that the FPS was around 500, but it kept dropping to 440 and that made horrible lag spikes so I wanted to set a max fps to stop the lag spikes, but I don't know how to do that. Game loop:

    public void run(){
    this.requestFocus();
    long lastTime = System.nanoTime();
    double amountOfTicks = 60.0;
    double ns = 1000000000/amountOfTicks;
    double delta = 0;
    long timer = System.currentTimeMillis();
    int frames = 0;
    while(running){
        long now = System.nanoTime();
        delta += (now - lastTime) / ns;
        lastTime = now;
        while(delta >= 1){
            tick();
            delta--;
        }
        if(running)
            render();
    frames++;

    if(System.currentTimeMillis() - timer > 1000){
        timer += 1000;
        System.out.println("FPS: " + frames);
        frames = 0;
        }
    }
    stop();
}

Answer 1

Just use the same control mechanism you used to control the number of ticks. Try this, and put the max FPS you desire in the 'amountOfRenders' variable.

public void run(){
    this.requestFocus();
    long lastTime = System.nanoTime();
    double amountOfTicks = 60.0;
    double ns = 1000000000/amountOfTicks;
    double delta = 0;
    long timer = System.currentTimeMillis();
    int frames = 0;
    int ticks = 0;

    long renderLastTime=System.nanoTime();
    double amtOfRenders = 200.0;//MAX FPS
    double renderNs=1000000000/amtOfRenders;
    double renderDelta = 0;

    while(running){
        long now = System.nanoTime();
        delta += (now - lastTime) / ns;
        lastTime = now;
        while(delta >= 1){
            tick();
            ticks++;
            delta--;
        }

        now = System.nanoTime();
        renderDelta += (now - renderLastTime) / renderNs;
        renderLastTime = now;
        while(running && renderDelta >= 1){
            render();
            frames++;
            renderDelta--;
        }

        if(System.currentTimeMillis() - timer > 1000){
            timer += 1000;
            System.out.println("FPS: " + frames);
            System.out.println("Ticks per second: " + ticks);
            frames = 0;
            ticks = 0;
        }
    }
    stop();
}