null pointer exception in java when coding

Question

I am a newbie in objective programming so forgive me if this question is dumb.

I am developing a small to-do program as a exercise. But when I try to load existing txt file & folders for task storage, IDE told me Exception in thread "main" java.lang.NullPointerException. I read the popular one from this site describing this error, I kinda understood why it happened, but I just coudn't find the problem.

Line 17-26 of ListProcess:

public ListItem[] loadList() throws FileNotFoundException {
        ListItem[] listitem = new ListItem[200];
        int listCount=0;
        for (String txts : loadTxtsList()) {
            File file = new File(txts);
            Scanner scanner = new Scanner("List/"+file);
            listitem[listCount].isFolder = false;
            listitem[listCount].name = txts.replace(".txt", "");
            listitem[listCount].description = scanner.nextLine();
            int i = scanner.nextInt();

and yes, I'm using a class called ListItem to store these tasks.

ListItem class:

public class ListItem {
    boolean isFolder=false;
    String name;
    String description;
    String[] tags = new String[10];
    Status status;
}

If you re-read the "popular answer" it'll give you the tools to find the problem. Then the next time you get an `NPE` you'll know how to find the root of the problem and solve it yourself. The stacktrace tells you which line causes the exception, so you can track which variable is `null`. Your question doesn't contain the line number, so at least edit the question to include the stacktrace. — Kayaman, Mar 20 '20 at 14:59

score 0 · Accepted Answer · answered Mar 20 '20 at 14:59

0

The following line:

ListItem[] listitem = new ListItem[200];

creates an array whose items are all null.

answered Mar 20 '20 at 14:59

Andronicus

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null pointer exception in java when coding

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