Dropbox Core API JAVA Authorization Code

Question

Using the dropbox core api tutorial I am able to upload a file.

However, my question is an exact replica of this SO post--- That is, once I have my authorization code and comment out the user auth lines so that I dont have to manually re-authorize approval every time I use dropbox I get the following errors:

Exception in thread "main" com.dropbox.core.DbxException$BadRequest: {"error_description": "code has already been used", "error": "invalid_grant"}

OR

Exception in thread "main" com.dropbox.core.DbxException$BadRequest: {"error_description": "code has expired (within the last hour)", "error": "invalid_grant"}

I am positive I have the correct authorization code.

I hope that I'm missing something, else whats the point of an API if you have to induce manual intervention every time you use it?

Edit: My Exact Code (keys have been scrambled)

import com.dropbox.core.*;
import java.io.*;
import java.util.Locale;

public class DropboxUpload {
    public static void main(String[] args) throws IOException, DbxException {
        // Get your app key and secret from the Dropbox developers website.
        final String APP_KEY = "2po9b49whx74h67";
        final String APP_SECRET = "m98f734hnr92kmh";

        DbxAppInfo appInfo = new DbxAppInfo(APP_KEY, APP_SECRET);

        DbxRequestConfig config = new DbxRequestConfig("JavaTutorial/1.0",
            Locale.getDefault().toString());
        DbxWebAuthNoRedirect webAuth = new DbxWebAuthNoRedirect(config, appInfo);

        // Have the user sign in and authorize your app.
        //String authorizeUrl = webAuth.start();
        //System.out.println("1. Go to: " + authorizeUrl);
        //System.out.println("2. Click \"Allow\" (you might have to log in first)");
        //System.out.println("3. Copy the authorization code.");
        //String code = new BufferedReader(new InputStreamReader(System.in)).readLine().trim();

        DbxAuthFinish authFinish = webAuth.finish("VtwxzitUoI8DDDLx0PlLut5Gjpw3");
        String accessToken = authFinish.accessToken;

        DbxClient client = new DbxClient(config, accessToken);

        System.out.println("Linked account: " + client.getAccountInfo().displayName);

        File inputFile = new File("/home/dropboxuser/Documents/test.txt");
        FileInputStream inputStream = new FileInputStream(inputFile);
        try {
            DbxEntry.File uploadedFile = client.uploadFile("/Public/test.txt",
                DbxWriteMode.add(), inputFile.length(), inputStream);
            System.out.println("Uploaded: " + uploadedFile.toString());
        } finally {
            inputStream.close();
        }

        DbxEntry.WithChildren listing = client.getMetadataWithChildren("/");
        System.out.println("Files in the root path:");
        for (DbxEntry child : listing.children) {
            System.out.println("    " + child.name + ": " + child.toString());
        }

        FileOutputStream outputStream = new FileOutputStream("test.txt");
        try {
            DbxEntry.File downloadedFile = client.getFile("/Public/test.txt", null,
                outputStream);
            System.out.println("Metadata: " + downloadedFile.toString());
        } finally {
            outputStream.close();
        }
    }
}

Answer 1

You should be storing and reusing the access token, not the authorization code.

So after doing this once:

String accessToken = authFinish.accessToken;

You should just replace the whole thing with

String accessToken = "<the one you already got>";

BTW, if you just need an access token for your own account, you can generate one with the click of a button! See https://www.dropbox.com/developers/blog/94/generate-an-access-token-for-your-own-account.