Why cant I add 2 doubles together

Question

So I am making a simple game with spites. But im having some issues with the tick/render loop.

I need it to run at 30 ticks a second. But the fps needs to be as fast as it can.

The issue I am having is the while loop doesn't run

lastTime += msPerTick;

So my output looks like this. No adding. No loop. No render.

x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333
x:0.375 y:0.03333333333333333

Here is a snippet of the code. Let me know if you need more.

public  static final int  TICKS_PER_SECOND = 30;
private static final int  MAX_TICKS_PER_FRAME = 10;
private boolean       running;
private Thread        thread;
private int           tickCount;
private int           frames;
private boolean       paused;

public void run() {
    init();
    float lastTime = (System.nanoTime() / 1000000) / 1000.0f;
    running = true;

    double msPerTick = 1.0 / TICKS_PER_SECOND;

    while (running) {
        synchronized (this) {
            float now = (System.nanoTime() / 1000000) / 1000.0f;
            int frameTicks = 0;
            while (now - lastTime > msPerTick) {
                System.out.println("x:" + (now - lastTime) + " y:" + msPerTick);

                if (!paused && frameTicks++ < MAX_TICKS_PER_FRAME) 
                    tick();


                lastTime += msPerTick; //<-- Issue here
            }

            if (!paused) {
                render((now - lastTime) / msPerTick);
            }
        }

        //Thread.yield(); No need for yield lets use sleep.
        try {
            Thread.sleep(paused ? 500 : 1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

Answer 1

Because you're not adding 2 doubles. If you change the type of lastTime to double the code will work fine.

float f = (float) 0.2; double d = 2;

f += d => 2.0 d += f => 2.2