Since the tank must be deselected at the time of the click to move it, the movement will have to be controlled by the tank itself; if deselecting was done after the tank has finished moving, I would say to code it in the world class. Either way, however, the selecting itself will need to be done in the world class using a field to hold any tank clicked on -- detect first click and save tank in field; detect second click, tell tank where to go and clear field (reset its value back to 'null'). The state of the field, whether it contains a tank object or has a 'null' value, can be used to determine which click is which. You will need a method in the class of the tank that the world can call so it can prepare its trek. Call it 'proceedToClick()'. Acquiring the MouseInfo object can be done inside this method (the world does not need a MouseInfo object on the second click; it only needs to know that a click event occurred while a tank object was stored in the field). For the first click, however, the world will need to get a MouseInfo object and determine if the click was indeed on a tank (use the 'instanceof' conditional operator) and then save that tank in the field, if so. Do what you can with what was given and if you encounter any specific problems, post the code and explain for help.

Declare the field outside the method. That is, instead of a variable that is local to a method -- like this: You would do this: By declaring the field outside the method, it is retained for as long as this object exists ('this object' being the current world object, since we are in your world class -- your class that extends World).