How to decide face side of sprite

Question

I am just starting game-dev with slick2D and marte engine. When I move my sprite left and right, I am doing walk animation but when the key is released how can I decide in which side the sprite face to set?

Here's the relevant code:

    Input ip = gc.getInput();

    if (ip.isKeyDown(Input.KEY_RIGHT))
    {
        this.currentAnim = "Anim2";
        System.out.println("down");
        x += 0.1f * delta;
    }

    if (ip.isKeyDown(Input.KEY_LEFT))
    {
        this.currentAnim = "Anim4";
        System.out.println("down");
        x -= 0.1f * delta;
    }

Answer 1

You might be overthinking this because this is extremely simple. Try thinking about it conceptually before you start thinking in code.

Your question is: which side should the sprite face after walking

The answer you want is: it should face the side the sprite walked towards

To decide that each frame we need to store lastDirectionWalkedTowards but lets abbreviate that a bit and call it facing. Now since your sprites move along the X-axis we only have to know if its left or right. You can create an enum for this but even easier would be to store it as an int, with +1 meaning facing right and -1 meaning facing left. We can use 0 for neutral when we havent walked yet, and use some sane default.

The complete psuedo code:

int facing = 0; //class member

//in the update method

if (ip.isKeyDown(Input.KEY_RIGHT))
{
    facing = 1;

    this.currentAnim = "Anim2";
    System.out.println("down");
    x += 0.1f * delta;
}
else if (ip.isKeyDown(Input.KEY_LEFT))
{
    facing = -1;

    this.currentAnim = "Anim4";
    System.out.println("down");
    x -= 0.1f * delta;
}
else // if no directional key was pressed
{
    if(facing == -1) // if facing left
    {
        this.currentAnim = "LookLeft";
    }
    else // if facing right or neutral
    {
        this.currentAnim = "LookRight";
    }
}