Sprite - rotation acceleration

Newbie & Debugging Questions
#1

Hello

I want to create a “sprite” whose rotation is accelerating and when I press button (‘A’ for example) acceleration slows down.
This is what I created:

	
private void update()
	{

		if(1 < 2)
		{
			rotation=1;
			time += Gdx.graphics.getDeltaTime();
			rotation *= time * temp;
			System.out.println("time " + time);
			System.out.println("rotation " + rotation);
			System.out.println("temp " + temp);

			if(rotation > 360)
			{
				time = 0;
				temp += 30;
			}
			else if(Gdx.input.isKeyPressed(Keys.A))
			{
				rotation -= 4.0f;
				time = 0;
				temp /= 1.01;
			}
		}
	}

and render:

batch.draw(kreska2, Gdx.graphics.getWidth()/2-kreska.getWidth()/2, Gdx.graphics.getHeight()/2, 0, 0, kreska.getWidth(), kreska.getHeight(), 1, 1, rotation);
  1. Iis it designed in the correct way? Or it is piece of…?
  2. How to create a smooth acceleration?
  3. (It is main question) Right now when I press ‘A’ rotation speed will slow down but angle will be set to 0. When I will just use ‘rotation -= 4.0f;’ to slow down rotation, that the angle will go back several degrees. How to handle this topic?