Using a string as a directory from excel to change the image in a JLabel

Question

I feel that's the most accurate title ever created and says exactly what I need. I am making a card game in Java and have loaded all the cards stats into a spreadsheet. I'm using the JXL api to read the spreadsheet and grab the stats for each card from its respective cell in the spreadsheet and store them in a Deck object and everything works really great there, but when I try to use the string that the getImage() returns, I keep getting a null pointer and I can't figure out why. I'll post everything I think is relevant, please let me know if more is needed.

The first part is from the class LoadCards that loads the spreadsheet and attaches the data to a Deck object. Note: i only have one attempt here as a test to make sure it's working and it's not.

public class LoadCards 
{
public Deck LoadCards()
{
    Workbook cardList  = null;
    try
    {
        cardList  = Workbook.getWorkbook(new File("C:\\DC Card Game\\src\\DCCardGame\\resources\\CardList.xls"));
    }
    catch (IOException e)
    {
        String message = "The file titled CardList.xls was not found.";
        String title = "File Not Found";
        JOptionPane.showMessageDialog(null, message, title, JOptionPane.ERROR_MESSAGE);
    } catch (BiffException ex) 
    {
        String message = "File must have an extension of .xls";
        String title = "Incompatible CardList File";
        JOptionPane.showMessageDialog(null, message, title, JOptionPane.ERROR_MESSAGE);
    }        
        Sheet typeSheet = cardList.getSheet(0);
        Sheet equipmentSheet = cardList.getSheet(1);
        String equipmentType = typeSheet.getCell(0,1).getContents();
        Deck testCard= new Deck(equipmentSheet.getCell(0, 1).getContents(),equipmentType,Integer.parseInt(equipmentSheet.getCell(2,1).getContents()),Integer.parseInt(equipmentSheet.getCell(3,1).getContents()),Integer.parseInt(equipmentSheet.getCell(4,1).getContents()),equipmentSheet.getCell(5,1).getContents());

        return testCard;

That last line builds an object for the Deck constructor which looks like this:

public Deck(String cardName, String type, int cost, int value, int power, String image)
{
    super();
}

And Deck extends Card, where all the appropriate getters/setters are.

public Card(String cardName, String type, int cost, int value, int power, String image)
{
    this.cardName = cardName;
    this.type = type;
    this.cost = cost;        
    this.value = value;        
    this.power = power;
    this.image = image;
}

In my form class, this is my code I'm using to test if the image is working (hint: it's not.) It keeps throwing a NullPointerException

LoadCards test = new LoadCards();
test.LoadCards();
ImageIcon testImage = new ImageIcon(getClass().getResource(test.LoadCards().getImage()));
extraLineupSlot1.setIcon(testImage);

I need to figure out how I can correct this so that I can call the string from my spreadsheet that will represent a directory, the directory is stored in the image property of the Deck/Card object, and then I can call that property and change the icon associated with the different JLabels I've made.

Answer 1

It sounds like you're able to get the list of strings, but you're having trouble getting the corresponding named resource. In this related example, a List<String> of names shares a common index with a List<ImageIcon> that serves as a cache of images stored as resources in a JAR. The method getImage(int index) returns an existing image from the cache or loads the image via getResource() for future reference. You might compare your approach. See the info for embedded-resource for more examples.