NullPointerException While adding JLabel to JPanel

Question

Im getting this strange NullpointerException whilst adding a JLabel to a JPanel:

    loadoutAdvWeaponPanels = new JPanel[4][4];
    loadoutAdvWeaponButtons = new JButton[4];
    loadoutAdvPistolLabels = new JLabel[4][8];

    //Init loadoutAdvPanels[0]

    loadoutAdvWeaponButtons[0] = new JButton("Pistols");

    loadoutAdvPistolLabels[0][0] = new JLabel("USP-S");
    loadoutAdvPistolLabels[0][1] = new JLabel("P2000");
    loadoutAdvPistolLabels[0][2] = new JLabel("Dual Berettas");
    loadoutAdvPistolLabels[0][3] = new JLabel("P250");
    loadoutAdvPistolLabels[0][4] = new JLabel("Five-SeveN");
    loadoutAdvPistolLabels[0][5] = new JLabel("CZ75-Auto");
    loadoutAdvPistolLabels[0][6] = new JLabel("Desert Eagle");
    loadoutAdvPistolLabels[0][7] = new JLabel("R8 Revolver");

    loadoutAdvWeaponPanels[0][0].add(loadoutAdvPistolLabels[0][0]);

The error occurs in the last line, but i dont know why.

score 0 · Answer 1 · edited Aug 21 '20 at 13:29

0

you should initialize the array loadoutAdvWeaponPanels

    loadoutAdvWeaponPanels = new JPanel[4][4];
    for(int i = 0; i < loadoutAdvWeaponPanels.length; i++)
        for(int j = 0; j < loadoutAdvWeaponPanels[i].length; j++)
            loadoutAdvWeaponPanels[i][j] = new JPanel();

or just initialize what you need

    loadoutAdvWeaponPanels[0][0] = new JPanel();
    loadoutAdvWeaponPanels[0][0].add(loadoutAdvPistolLabels[0][0]);

edited Aug 21 '20 at 13:29

Nowhere Man

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answered Aug 12 '17 at 13:02

Ali Faris

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use a generic for loop! – Niton Aug 12 '17 at 13:06
yup, thanks, didnt see that i still needed to initialize the panel and not only the array... – Tom_There Aug 12 '17 at 13:06

score 0 · Answer 2 · edited May 26 '20 at 06:31

0

Simple as I see!

You do not initialisized loadoutAdvWeaponPanels[0][0]

I prefer to use this:

for(int i = 0; i < loadoutAdvWeaponPanels.length; i++) {
    for(int j = 0; loadoutAdvWeaponPanels[i].length; j++) {
    {
         loadoutAdvWeaponPanels[i][j] = new JPanel();
    }
}

edited May 26 '20 at 06:31

marc_s

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answered Aug 12 '17 at 13:03

Niton

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yep, just saw it as well, sorry... – Tom_There Aug 12 '17 at 13:05

NullPointerException While adding JLabel to JPanel

2 Answers2