java.lang.NullPointerException

[meager radish]

Been getting this issue with my code, Im creatint a game using processing and Ive tried debugging it, im a beginner so idk how im supposed to fix it or where is causing the issue

i think this is the line causing the issue

        try {
            // System.out.println("Half of setup :D");
            board.loadLevel(this.getClass().getResource("level1.txt").getPath().toLowerCase().replace("%20", " ")); 
            // System.out.println("this prints :D");
        } catch (IOException e) { 
            System.out.println("not working :(");
            e.printStackTrace();
        }

Help 😦

[lone lichen]

Detected code, here are some useful tools:

[WARNING] The code couldn't end properly...

Problematic source code:

try {
            // System.out.println("Half of setup :D");
            board.loadLevel(this.getClass().getResource("level1.txt").getPath().toLowerCase().replace("%20", " ")); 
            // System.out.println("this prints :D");
        } catch (IOException e) { 
            System.out.println("not working :(");
            e.printStackTrace();
        }```
Cause:
The code doesn't compile:
cannot find symbol
  symbol:   variable board
  location: class 
non-static variable this cannot be referenced from a static context
cannot find symbol
  symbol:   class IOException
  location: class 

## System out
[Nothing]

<@&987246399047479336> please have a look, thanks.

[surreal lava]

Provide the stack trace. It points to the exact line where the exception occurred

[meager radish]

Line 62

[surreal lava]

I suspect the issue comes from getClass().getResource("level1.txt")

[meager radish]

Can provide a bigger snippet if needed

[alpine acorn]

If you place a breakpoint you can debug it.

For example is your board not null?

[meager radish]

How do i do that

[alpine acorn]

It depends on your IDE.

[meager radish]

this.getClass().getResource("level1.txt").getPath(), StandardCharsets.UTF_8.name())
``` tried this as well and doesnt work

[alpine acorn]

https://www.jetbrains.com/help/idea/using-breakpoints.html

[meager radish]

Im using java 8 on vsc for context

processing papplet

[surreal lava]

You can't bruteforce a solution, it's not how you are supposed to write code

[alpine acorn]

I recommend using intelliJ, it has better debugging.

And java 9 and later have better nullpointerexceptions.

At first glance your file isn't found.

[meager radish]

Do you know what possibly could be the issue tho?

[surreal lava]

Depending on where your file is located, you might need to use another matter of loading a file. If it's located in the project's root directory, then Path.of("level1.txt") would be sufficient.

[alpine acorn]

So dependant on your project setup it might not be detected as a resource folder.

[meager radish]

its inside a resources folder

[alpine acorn]

src/main/resources?

[meager radish]

It detects my other sprites tho

No

src/main/inkball/resourses

    public void loadLevel(String filePath) throws IOException {
        System.out.println("working :D");

the print line doesnt even run when i call this using the initial issue as well

so im suspecting its the way i grab for the file

[surreal lava]

Are you building your project using maven/gradle? Behavior may vary from a tool to another tool

[meager radish]

gradle

[alpine acorn]

Because a Nullpointer isn't an IOException.

[meager radish]

Ye but u need to catch that just incase no?

[alpine acorn]

If you were to put Exception ex there you would see the exact exception.

[meager radish]

Otherwise u get an error

[alpine acorn]

I was just explaining why you weren't seeing your print statement.

[meager radish]

Oh yea

[alpine acorn]

Since nullpointers are runtime exceptions.

[surreal lava]

Right, so it should be under src/main/resources. If other resources in the same directory are loaded fine, then that particular file might have not been copied during the build

[meager radish]

should i also make an exception

[meager radish]

mhmm yep

[surreal lava]

You better familiarize yourself with a debugger. It will save you a lot of time.

[meager radish]

What does that mean

[raw heath]

are you using processing ?

[meager radish]

Im 8 weeks into learning java 😢

[meager radish]

yep

[meager radish]

context **

[alpine acorn]

What I linked earlier.

[surreal lava]

Should've learned debugging on the first day 🙂
Jokes aside, this might help you: https://code.visualstudio.com/docs/java/java-debugging

[meager radish]

would u say the lines of println is doing the same thing ish

[raw heath]

a few problems

• if you have src/main/resources/Level1.txt then the path should be /Level1.txt
• don't use regular io to load stuff from resources, you can't, you have to use getResource or getResourceAsStream. I repeat, File, Path and Files won't work.
• processing isn't compatible with resources so depending of what you need to load, you can't use resources

and also, please show loadLevel

[meager radish]

    public void loadLevel(String filePath) throws IOException {
        System.out.println("working :D");
        Level_loader level_loader = new Level_loader(p.loadJSONObject("config.json"), spriteManager);
        System.out.println("still working :D");
        level = level_loader.loadLevel(filePath);
        System.out.println("even more working :D");
    }

[surreal lava]

I'm not familiar with VSCode in particular so can't guide you there. The overall process consists of you placing a special marker somewhere in your code where you want the program to stop for further analysis; once you run your program in a special "debug" mode, it will stop right at the marker, showing its current state, local variables, etc. From here, you can determine what caused an issue.

[raw heath]

what is p ?

[meager radish]

  public Board(PApplet p, SpriteManager spriteManager) {
        this.level = null;
        this.p = p;
        this.spriteManager = spriteManager;
        this.score = 0;
        this.isPaused = false;

    }

[raw heath]

right so that's processing

[meager radish]

Mhmm

[raw heath]

so you can't use processing with resources

instead put them in a data folder outside of src

it should work

[meager radish]

Wdym?

[surreal lava]

Why are you using a different approach for loading the map file? If the config loads just fine, place the map next to it and use the same API for reading it

[raw heath]

what do you not understand ?

[meager radish]

Coz like i have other resources sucha as sprites n .json that work completely fine tho

[meager radish]

^

[raw heath]

what do you not understand ?

[raw heath]

it shouldn't

[meager radish]

why tho

[raw heath]

because that's how processing was coded

[meager radish]

Ill give u an example sec

[raw heath]

Ah I think I understand, it's a coincidence, don't do that

[meager radish]

    public PImage getSprite(String s) {
            PImage result = sprites.get(s);
            if (result == null) {
                result = loadImage(this.getClass().getResource(s + ".png").getPath().toLowerCase().replace("%20", " ")); 
                sprites.put(s, result);
            }
            return result;
        }

can u explain why this works and not the board one? arent they kinda similar in a way tho?

[raw heath]

yea don't

[raw heath]

it depends of what s is

[meager radish]

is it not supposed to work?

does it just not work with txt files

[raw heath]

it works because of a coincidence

[meager radish]

Can i make that miricle happen again then or?

[raw heath]

it doesn't matter what kind of files it is, you are not supposed to read resources like this, like I explained

[raw heath]

you could, but like I said, you shouldn't

[meager radish]

Is it supposed to be a local file

[raw heath]

you are abusing features in unintented ways

and it may break at any moment

[meager radish]

Whats the easiest band aid fix then

[raw heath]

I already explained everything

[meager radish]

Move it outside my src?

how do i call it then

[raw heath]

• if you have src/main/resources/Level1.txt then the path should be /Level1.txt
• don't use regular io to load stuff from resources. You can't. You have to use getResource or getResourceAsStream. I repeat, File, Path and Files won't work.
• processing isn't compatible with resources, so depending of what you need to load, you can't use resources, you have to create a data folder outside of src

[meager radish]

board.loadLevel(this.getClass().getResource("level1.txt").getPath().toLowerCase().replace("%20", " ")); 

i am usig getresources here tho

[raw heath]

please read what I wrote

I have three points

you broke all three

[meager radish]

So im missing a / for the first one

2nd one?

I get the 3rd one

[raw heath]

what does getPath return ?

[meager radish]

No clue

[raw heath]

then check what it returns with your ide

mouse over getPath

[meager radish]

is it returning null?

[raw heath]

Ah my bad

Let me fix my message

[meager radish]

Java hurts my brain 😦

[raw heath]

• if you have src/main/resources/Level1.txt then the path should be /Level1.txt
• don't use regular io to load stuff from resources. You can't. You have to use getResource or getResourceAsStream. I repeat, File, Path and Files won't work. Ah and you can't use raw strings either.
• processing isn't compatible with resources, so depending of what you need to load, you can't use resources, you have to create a data folder outside of src

[meager radish]

Do i need a file getter or soemthing as well?

[raw heath]

no

you can't use regular io

you have to use getResource or simpler, getResourceAsStream

[meager radish]

Im still not understanding, because i am using getResource here tho

this.getClass().getResource("/level1.txt").getPath().toLowerCase().replace("%20", " ")```

[raw heath]

you do, but then you get rid of it to then use regular io

[meager radish]

There is getResource

[raw heath]

you are supposed to only use getResource

nothing else

[meager radish]

Ok ok

[raw heath]

(well, uri also works I guess)

[meager radish]

this.getResource("/level1.txt").getPath().toLowerCase().replace("%20", " ")?

like this or smth?

[raw heath]

no

you are still doing the same thing

you can only use getResource or getresourceAsStream

nothing else

[meager radish]

so the updated would be

            // System.out.println("Half of setup :D");
            board.loadLevel(.getResource("/level1.txt")); 
            // System.out.println("this prints :D");
        } catch (IOException e) { 
            System.out.println("not working :(");
            e.printStackTrace();
        }

Yes?

[raw heath]

and now it doesn't compile

i'm telling you

[meager radish]

What am i doing wrong now??

[raw heath]

you can't do that

[raw heath]

this isn't valid java

you can't put a .something out of nowhere

[meager radish]

o lol woops

[raw heath]

anyway

forget about getResource

[meager radish]

im getting this anyways

[raw heath]

usually you would only use getResourceAsStream

well yes

[meager radish]

ok

[raw heath]

but

[meager radish]

Ill google it...

[raw heath]

please

let me explain

[meager radish]

ok ok

my listening ears are open

[raw heath]

usually you would only use getResourceAsStream

forget about getResource

but processing is a particular case

you can't use resources at the first place

and so this is where my 3rd point comes

you have to add a data folder above src

[meager radish]

Yep

[raw heath]

and use a relative path

[meager radish]

And u would only use that?

For most things

[raw heath]

for specifically processing yes

whenever processing asks you for a path

put the file in data

and give the file name as the path

[meager radish]

ok ok

is that why my images work fine?

[raw heath]

the reason why your messages work fine is because you followed point 1 correctly, compared to here
But like I said, this is a coincidence, the reason why it works fine even if you are using a resource is because you are using regular io on an absolute path.
But those resources can be transformed depending the situation. For example, if you try to make a jar, it would totally break, because regular io can't handle files inside a jar. But getResource and getResourceAsStream can

[meager radish]

Hmm so I should be fine using either of them from now on?

Great thanks

[raw heath]

no, at best you are misusing it