Java: Can't access variable?

Question

So i'm having a bit of a problem trying to compare two strings declared in the Main class. I've messed around with it and i really can't get it to work! The problem is in the if() statement where i compare the variables...

public class Main {

    public String oldContent = "";
    public String newContent = "";

    public static void main(String[] args) throws InterruptedException {
        Main downloadPage = new Main();
        downloadPage.downloadPage();
        oldContent = newContent;

        for (;;) {
            downloadPage.downloadPage();
            if (!oldContent.equals(newContent)) { // Problem
                System.out.println("updated!");
                break;
            }
            Thread.currentThread().sleep(3000);
        }
    }

    private void downloadPage() {
        // Code to download a page and put the content in newContent.
    }
}

Dan · Accepted Answer · 2011-04-16 16:29:53Z

3

the variables are instance members, whereas the for happens in a static method. try moving the actual function to an instance method (not static), or conversely make the data members static as well.

answered Apr 16, 2011 at 16:29

Dan

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1 Comment

omp Over a year ago

I tried ticking it at first, but stackoverflow was being b*tchy! Ticked now! :)

Reza · Accepted Answer · 2011-04-16 16:34:08Z

2

You may use name of the object you have created (downloadPage ) to access to the parameters: in the main finction use following instead of parameter names only:

downloadPage.oldContent
downloadPage.newContent

answered Apr 16, 2011 at 16:34

Reza

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Comments

Matheus Moreira · Accepted Answer · 2011-04-16 16:34:15Z

1

The variables are inside the Main object:

public static void main(String[] args) throws InterruptedException {
    Main downloadPage = new Main();
    downloadPage.downloadPage();  // Access them like you accessed the method
    downloadPage.oldContent = downloadPage.newContent;

    for (;;) {
        downloadPage.downloadPage();
        if (!downloadPage.oldContent.equals(downloadPage.newContent)) {
            System.out.println("updated!");
            break;
        }
        Thread.currentThread().sleep(3000);
    }
}

Do consider using getters and setters instead of exposing the fields.

answered Apr 16, 2011 at 16:34

Matheus Moreira

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Comments

Community · Accepted Answer · 2017-05-23 09:58:49Z

0

See non static/ static variable error

edited May 23, 2017 at 9:58

CommunityBot

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answered Apr 16, 2011 at 16:34

sbridges

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