It might just be because you have a link to an outside site referenced in your world code.

That's quite unfortunate... How else am I supposed to scroll? What I need is for the world to display a number of string elements line-by-line, with the ability for the user to scroll through the string elements (Additionally, is there any way for these string elements to be bounded to certain dimensions other than the world's dimensions, and to stop displaying a specific element if it's outside these boundaries?) That's a likely possibility. I didn't know this was a thing though, and they're only links to java-tutorial related websites and forums, Greenfoot discussions included. There isn't anything I can really do about this, is there?

There are others ways to scroll -- and your text image can provide the limits of scrolling. Scrolling can be controlled by mouse clicking on "scroll" objects, mouse dragging on text image or on "scroll" bars or by specific keypresses (like on arrow keys, for example). My Scrolling Tutorial scenario includes mouse dragging and keyboard scrolling and my TextFile Viewing World Class scenario is an example of using "scroll" objects (buttons and bars).

I'm going through the scrolling scenario, but I have one question; does the scroll bar scroll for a maximum length? Because the scroll bar/methods that I need must be able to scroll flexibly (depending on file size that the text is read from). Also, it is likely that the text will be long enough to go off-screen, how do I make the text automatically newline after a certain number of characters? I think the world dimensions of 420, 600 can fit ~43 chars horizontally, not sure though.

No. It is dependent on the length of the text at hand. I suggest you use mouse dragging which will easily allow for scrolling both vertically AND horizontally.

Interesting. Only issue with that is that the text will (in most worlds where scrolling is used) be clickable, making a possible problem for the user. On the other hand, that isn't in my documentation so I don't need to compensate for this, and this is for a school project so the user doesn't entirely matter. Thanks. I'll look into that. Have you made any scenarios on mouse dragging that I could look at?

There is my Scroller Class Demos scenario. At the bottom of the initial page of the Scrolling Tutorial, you will find a link to Mouse drag controlled scrolling code used by a world.

Thanks, I'll get back to you on how that goes. In the mean time, I have a rather odd question: Can classes (more specifically, world classes) have a return type? e.g. I highly doubt the answer is yes, but hey, worth a shot. What I mean by that is; Main world (calculator) User changes mode (World: mode select) User selects calculation history mode (World: show calc history) Information (calculation history) is retrieved from file and displayed on-screen User selects one specific calculation by clicking on it The answer to that calculation is transferred from show calc history world to actor calculate in main world So far I've used a separate constructor in the main world to transfer this information upon world change (which will happen immediately after text is clicked) but is there a better way to do this?

Sorry, I know I'm asking a few too many questions on this one discussion, but I've just noticed an issue. Every minute or so, my main world re-initialises itself which causes a lot of lag when editing the code. I've checked through every class that involves the main world, but none of them ever use Calculator = new Calculator(); so I don't know what could be causing the start-up terminal message to pop up ~6 times upon completely closing and reopening greenfoot. Might be a temporary issue involving some iffy syntax in a recent edit, but I'm unsure.

Line 3, because it contains a return type, is not a constructor declaration, but is instead a method declaration. Depending on exactly what you are dealing with, you may be able to use static content for this, as long as nothing involves any state or behavior of the current World object. That is, as long as it can be done without referencing the active World objecct (cannot use "this", explicitly or implicitly). Shot entire terminal output (copy all/paste).

Yeah, I thought something along those lines. Didn't think that would work. Again, was worth a shot. That seems more reasonable. How do I make a class static? One of my classes is (technically) static but not really, the class itself isn't static but all its methods and attributes are static. It works as far as I know. It's just a bunch of the same message that prints to the terminal when the main world is initialised, greeting the user and requesting for bug reports. Was repeated ~6 times in the terminal (no other terminal messages) upon starting Greenfoot last night. Don't think I'm having this issue anymore, but I can't be sure.

Ah, I've found the problem that was causing the lag. I'm no longer having the issue of the initial message popping up multiple times, but I have found that I should have put the 'createFiles()' method before other method calls in the world constructor rather than after, and made certain classes static. I am getting a different issue, the terminal is showing: java.io.FileNotFoundException: Constants.txt (The system cannot find the file specified) at java.base/java.io.FileInputStream.open0(Native Method) at java.base/java.io.FileInputStream.open(FileInputStream.java:219) at java.base/java.io.FileInputStream.<init>(FileInputStream.java:157) at java.base/java.io.FileInputStream.<init>(FileInputStream.java:112) at java.base/java.io.FileReader.<init>(FileReader.java:60) at Constant.<init>(Constant.java:35) at Calculate.<init>(Calculate.java:29) at RightArrow.<init>(RightArrow.java:13) <-- This terminal message is repeated for each arrow (up, down, left, right) and I'm not sure why. The arrows don't relate to files at all. When clicked, it highlights the line in arrow "Calculate cal = new Calculate();" which makes me think that the arrows are only in the terminal because they create a new calculate object. at Calculator.makeArrowButtons(Calculator.java:164) at Calculator.<init>(Calculator.java:63) Ok, so while typing this, I noticed that one of the terminal error messages highlights a completely unrelated comment?! How? The comment relates to code that hasn't been implemented yet! I'm confused... at Calculate.<init>(Calculate.java:29) Referring back to the whole 'arrows' thing, how would I call a method within a class (specifically an actor subclass) without creating a new object of that class? I can't make the methods static (tried just now) because they're modifier method (like get/setPrivateVariableAttribute) that increments (down/right arrows) / decrements (up/left arrows) currentIndex, which is a non-static variable.

I was not saying to write another class. I was pointing out that maybe by using static methods and attributes (in a class you already have), you could accomplish what you were trying to do. Okay.

I believe you are needing this line: Then you can call the method on 'calculate'.

Yeah, I realised that my button class held the answer all along, but this page wasn't loading (505 error) so I couldn't post an edit. I was referring to a different class that I made static. I made 2 other classes static since then. I probably should've specified that I was referring to a different class, my bad. I still don't understand why a multi-line comment was involved in a terminal error message? I mean, it's no big deal, but still... Whoops, I wrote this last night and forgot to post...