Java Shooter Game - Player:: update() - http://tibor-simon.com/programming/auto-aiming-logic-for-games/

Player_update.java

...
if (autoAim) {
    // determine the rotation direction
    float base = image.getRotation();

    float d1 = calculateDistance(base, targetAngle);
    float d2 = calculateDistance(base-1.0f, targetAngle);

    // if the distance is greater than about 3 degree
    if (d1 >  0.05f) {
        if (d1 > d2) {
            turnLeft(delta);
        } else {
            turnRight(delta);
        }
    }
}
...