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Your current 'atWorldEdge' method has the checks that you need, but is using 20 pixels as the buffer. Remove that method and put the appropriate check with each key detected movement using 10 instead of 20. The left direction check/movement code would be: Add the appropriate check similarly for the right direction.

i have implemented the above code into greenfoot but my object is still touching the edge of the world but is not stopping 10 px before. here is my code: public void move() { //System.out.println("move funtion called"); /*if (Greenfoot.isKeyDown("up")){ setLocation(getX(), getY()-1); } if (Greenfoot.isKeyDown("down")){ setLocation(getX(), getY()+1); }*/ if (Greenfoot.isKeyDown("left")&& getX()>10){ //System.out.println("left key pressed"); setLocation(getX()-1, getY()); } if (Greenfoot.isKeyDown("right")){ setLocation(getX()+1, getY()); //System.out.println( "right key pressed"); } } public void act() { move(); } // public boolean atWorldEdge() // How to make the new object appear automatically onto the stage // if (getX() < 10 || getX() > getWorld().getWidth() - 10) { // return true; //} //if (getY() < 10 || getY() > getWorld().getHeight() - 10) { // return true; //} //return false; //} }

It should be stopping 10 pixels before the left edge of the world. It may not appear that way because it is the center of the image that will stop at that point. You still have not added the extra check for going right and the right side of the world, so the image should go half out of the world on the right still.

You could test it by using the following for the left direction check/movement, which will keep the whole image off the left side of the world by 10 pixels:

I have added the code to the right key movement, but when i try to move right from the edge of the world the object stops moving? here is my code public void move() { //System.out.println("move funtion called"); /*if (Greenfoot.isKeyDown("up")){ setLocation(getX(), getY()-1); } if (Greenfoot.isKeyDown("down")){ setLocation(getX(), getY()+1); }*/ if (Greenfoot.isKeyDown("left")&& getX()>10){ //System.out.println("left key pressed"); setLocation(getX()-1, getY()); } if (Greenfoot.isKeyDown("right")&& getX()>10){ setLocation(getX()+1, getY()); //System.out.println( "right key pressed"); } } public void act() { move(); } // public boolean atWorldEdge() // How to make the new object appear automatically onto the stage // if (getX() < 10 || getX() > getWorld().getWidth() - 10) { // return true; //} //if (getY() < 10 || getY() > getWorld().getHeight() - 10) { // return true; //} //return false; //} }

You did not add the appropriate check for the right direction. Look at the 'atWorldEdge' method code and determine the correct check to use. Once you have the right one in place, remove the whole 'atWorldEdge' method from the class code (you are not calling it from anywhere, anyway). EDIT: Oh, I see you at least commented it out.

i think i have now used the right check for the right movement of my object. but now the object gets stuck on the right edge of world when i try to move left what am i doing wrong? here is my code public void move() { //System.out.println("move funtion called"); /*if (Greenfoot.isKeyDown("up")){ setLocation(getX(), getY()-1); } if (Greenfoot.isKeyDown("down")){ setLocation(getX(), getY()+1); }*/ if (Greenfoot.isKeyDown("left")&& getX()>10+getImage().getWidth()/2){ //System.out.println("left key pressed"); setLocation(getX()-1, getY()); } if (Greenfoot.isKeyDown("right")&& getX()>10-getImage().getWidth()/2){ setLocation(getX()+1, getY()); //System.out.println( "right key pressed"); } } public void act() { move(); } // public boolean atWorldEdge() // How to make the new object appear automatically onto the stage // if (getX() < 10 || getX() > getWorld().getWidth() - 10) { // return true; //} //if (getY() < 10 || getY() > getWorld().getHeight() - 10) { // return true; //} //return false; //} }

The check does not compare the objects location (returned from 'getX()') to any location, or x value, near the right side of the world. The right-most location in the world is at 'getWorld().getWidth()-1'. Your check should be:

also the object does not buffer 10 px from the edge of the world on the right side when with if(Greenfoot.isKeyDown("right") && getX()>10-getImage().getWidth()/2)