ArrayList returns null

I want to use this method for filling my combobox, i want to store information in an Arraylist, but this returns null, wheni print the method:

Code:

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public ArrayList getPlaygroundStringList(Spel spelActief){
                   
        ArrayList <String> playgroundStringList = new ArrayList();
       
        for (int i = 0; i < spelActief.getPlaygroundAantal();i++)
            playgroundStringList.add(spelActief.playground.getNaam());
       
        return  this.playgroundStringList;
    }

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1. The parameter works
2. when i print this (spelActief.playground.getNaam()) i get:
playground1

The purpose is to fill this arraylist when passing a playground.
playground1, playground2 and so on.

Why does it return null?

Kind regards,

André

It's easy. You have two variables. There are have the same name and you pass variable, which you are not fulling. Just delete key work "this" from there

Code:

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return  [B]this[/B].playgroundStringList;

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Thanks, your right, it works.
The for loop gives me.

I made another mistake to add the for loop there.
result:
playground1, playground1, playground1, playground1

So i've changed that. So the result is:

playground1

And when i start in level two the result is:
playground2

It seems like the first value is gone.

How do i get it to save every value that the getMethod gives?

like this: playground1, playground2 etc..

The new keyword makes a new instance in the method. Thats why.

Sorry It's difficult to understand for me. You can use forEach loop for it.
What is "spelActief.getPlaygroundAantal()" there?

Not a problem.

That gives me the active playground.

So if i play in playground 1 it gives playground1, when i get to the next playground, it gives me playgroud2.

And i want to store everything it gives me after i played each playground in an ArrayList.

This is what i want (see code), i managed to do it now, but the code is not so flexibel.
spelActief.playground.getName()), gives me the playground i'm on at the moment, example: playground1.
spelActief.getPlaygroundAantal(); gives me the sixe of the playgroundList.

Code:

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public String[] getPlayground(Spel spelActief){

        String[] playGr1 = {"Playground 1"};
        String[] playGr2 = {"Playground 1", "Playground 2"};
        String[] playGr3 = {"Playground 1", "Playground 2", "Playground 3"};
        String[] playGr4 = {"Playground 1", "Playground 2", "Playground 3", "Playground 4"};

        if (spelActief.playground.getNaam().equals("playground1"))
            return playGr1;
        else if(spelActief.playground.getNaam().equals("playground2"))
            return playGr2;
        else if(spelActief.playground.getNaam().equals("playground3"))
            return playGr3;
        else
            return playGr4;
    }

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Code:

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playgroundComboBox = new JComboBox(spelHandler.getPlayground(spelActief));

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