CODEWITHSUNDEEP
javaswing
oipsl
oipsl

Reputation: 337

Trouble drawing multiple JLabels

I'm trying to draw 5 cards onto a JPanel, but am having trouble with displaying the card images.

JLabel[] cards = {
        new JLabel(CARD_BACK),
        new JLabel(CARD_BACK),
        new JLabel(CARD_BACK),
        new JLabel(CARD_BACK),
        new JLabel(CARD_BACK)
    };

    for(int i=0; i<cards.length; i++) {
        cards[i].setBounds(60*i, 0, 150, 215);
    }

    for(JLabel z : cards)
        auxHands.add(z);

    auxHands.setLayout(null);

The above works fine and draws 5 card images, but when I try to condense the code like this:

JLabel[] cards = new JLabel[5];

    Arrays.fill(cards, new JLabel(CARD_BACK));

    for(int i=0; i<cards.length; i++) {
        cards[i].setBounds(60*i, 0, 150, 215);
    }

    for(JLabel z : cards)
        auxHands.add(z);
    auxHands.setLayout(null);

it seems to only draw the last instance of the card. Eventually, I'm going to be drawing multiple hands, and it would seem tedious to keep instantiating a new JLabel[] as in the first code sample.

Here's a visual of what I mean: http://oipsl.freesuperhost.com/images/meh.png, the top half shows what it looks like when I execute the first snippet of code, while the bottom half is what it looks like with the second code snippet.

Upvotes: 2

Views: 218

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1499780

This code:

Arrays.fill(cards, new JLabel(CARD_BACK));

only creates a single JLabel. It then uses a reference to that single label for all elements in the array... hence the effect you're getting. It's equivalent to:

// Equivalent bad code
JLabel label = new JLabel(CARD_BACK);
JLabel[] cards = { label, label, label, label, label };

Hopefully you can see why that doesn't work.

You should use a loop which can populate the array with new labels and set the bounds at the same time. You can add it to auxHands at the same time too:

JLabel[] cards = new JLabel[5];
for (int i = 0; i < cards.length; i++) {
    JLabel label = new JLabel(CARD_BACK);
    label.setBounds(60*i, 0, 150, 215);
    auxHands.add(label);
    cards[i] = label;
}

Note that unless you need the array elsewhere, you could do away with it completely:

for (int i = 0; i < 5; i++) {
    JLabel label = new JLabel(CARD_BACK);
    label.setBounds(60*i, 0, 150, 215);
    auxHands.add(label);
}

Upvotes: 4

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