public class Transition{

    private float   startV,endV;
    private long    activeChange;
    private int     speed;

    public Transition(float initalValue, int speed){
        this.speed=speed;
        setInstant(initalValue);
    }

    public void setInstant(float value){
        startV=endV=value;
        activeChange=System.currentTimeMillis()-speed;
    }

    public void setSpeed(int ms){
        speed=ms;
    }

    public void setGoal(float value){
        startV=get();
        endV=value;
        activeChange=System.currentTimeMillis();
    }

    public float get(){
        float precent=getPrecent();

        if(precent<0) return startV;
        if(precent>1) return endV;

        return startV+(endV-startV)*precent;
    }

    public boolean changing(){
        if(startV==endV) return false;

        float precent=getPrecent();

        return precent>0&&precent<1;
    }

    private float getPrecent(){
        long past=System.currentTimeMillis()-activeChange;

        if(past>speed) return 1;
        if(past<0) return 0;

        return (float)(((double)past)/speed);
    }
}