ok, but how to make it moving back and forth? is this correct? if (!atWorldEdge()) {move(+1);} else (atWorldEdge()) {move(-1);} but this will make it not move right?

You will need to keep the direction in an instance field and perform a double conditional check to reverse direction. Using an int field is the easiest since you can set it to '1' and negate its value to reverse directions and use its value as a factor in the speed of the movement. Speed can be hard coded or it can also be held in an instance field.

Thanks for helping, but my elephant keep on banging the wall, reverse only 1 pixel then move forward 1 pixel and looping like that. sorry, i am so new in this. i try many times already. i just want my object to move like this... forward from here to here (O>) ---------------------------------------------------------------------------------------------> (O>) and then reverse tohere from here (O>) <----------------------------------------------------------------------------------------- (O>)

int direction=1; if ( getX() == 0 && direction == 1) move(direction); else if (getX() >0 || getX()<599 && direction == 1) move (direction); else if (getX()== 600 && direction == 1) move(-direction); else if (getX() <600 || getX()>0 && direction == -1) move(-direction);

You are checking to see if the value of 'direction' is positive one (1) and negative one (-1); yet, nowhere are you actually changing its value from positive one (1). First, check to see if the value of 'direction' needs changed (changing it if needed), then execute the moving.

thank you so much for your help.......i try to change a little...now it work.... i change your code from direction == -1 to direction > 0 thanks for everything. i need too study more.

Hello, I'm working on something very similar. move back and forth just like that except it move at different integers back and forth building up longer distances... like for example starting at 0, 1,-1,2,-2,3,-3 ect or also like 0,1,-2,4,-8,16 ect.

Isn't there a way to use the while or looping code to keep the act method going over and over. Then within the loop code, make a line of code that adds one to a and for the other algorithm, multiply a by 2. However, not sure how to set that coding up. A a = a + 1 A a = a * 2 Also, to comment about the coding above, it will not work for the idea that we are trying to do, downey, because the actor will move to the end of the world, then walk to the other side. We need to tweak the code to only move 1, the set a code to add one to the variable, and then move the same variable and do a forever loop.

I don't think that while loop makes sense. This should work I think.

If you use a while loop inside the act method, it, the while loop, will execute to completion in one act frame (or in about 1/60 of a second) and only the end result will be displayed on screen. The act method is already being called repeatedly while your scenario is running, in loop fashion. Only put code that describes what the actor should do at any instance in the act method. You can use an if statement to determine when to turn around and increase speed.(or for whatever does not happen constantly).

So, I appreciate the help, but I input this code and my actor "freaks" out. It moves back and forth but super fast, but never really leaves the one spot.... Hehe!