CODEWITHSUNDEEP
javaswingjpanellayout-managergridbaglayout
user2152962
user2152962

Reputation: 47

Center Components in JPanel with GridBagLayout

I am having an issue with the alignment of components in my JPanel which has a GridBagLayout. The JLabel is on the top, but not centered, and the JButtons underneath are positioned all the way to the right. Is there any way I can position them both in the center? Here is the method in which I initialize my GUI.

public void initialize() {
        JButton[] moveChoices = new JButton[3];
        JPanel buttonsPanel = new JPanel();
        buttonsPanel.setBackground(Color.green);
        buttonsPanel.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();
        JLabel welcome = new JLabel();
        for(int i = 0; i < moveChoices.length; i++) {
            moveChoices[i] = new JButton();
            c.gridx = i;
            c.gridy = 1;
            if (i == 0) c.anchor = GridBagConstraints.EAST;
            if (i == 2) c.anchor = GridBagConstraints.WEST;
            moveChoices[i].addActionListener(this);
            buttonsPanel.add(moveChoices[i], c);
        }

        moveChoices[0].setText("Rock");
        moveChoices[1].setText("Paper");
        moveChoices[2].setText("Scissors");

        welcome.setText("Welcome to rock paper scissors! Please enter your move.");
        c.gridy = 0; c.gridx = 1; c.insets = new Insets(10, 0, 0, 0);
        buttonsPanel.add(welcome);
        winText = new JLabel();
        buttonsPanel.add(winText, c);
        this.add(buttonsPanel);
    }

Upvotes: 2

Views: 9271

Answers (1)

functionpointer
functionpointer

Reputation: 1441

Here is your code in a form that works. To make it work, you need to to the following things:

  1. all buttons need the same amount of weightx, to get the space evenly distributed between them
  2. the heading needs some weightx to get all the of its row
  3. use fill=BOTH to make all components fill the space they get
  4. use gridwidth to make the heading use three columns while the buttons only use one
  5. use the horizontal alignment of JLabel to make the heading centered within its space
public void initialize() {
    JButton[] moveChoices = new JButton[3];
    JPanel buttonsPanel = new JPanel();
    buttonsPanel.setBackground(Color.green);
    buttonsPanel.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    JLabel welcome = new JLabel();
    c.fill=GridBagConstraints.BOTH;
    c.anchor=GridBagConstraints.CENTER;
    welcome.setText("Welcome to rock paper scissors! Please enter your move.");
    welcome.setHorizontalAlignment(SwingConstants.CENTER);
    c.weightx=1;
    c.gridy = 0; c.gridx = 0; c.insets = new Insets(10, 0, 0, 0);
    c.gridwidth=moveChoices.length;
    c.gridheight=1;
    buttonsPanel.add(welcome,c);
    c.insets=new Insets(0,0,0,0);
    c.gridwidth=1;
    for(int i = 0; i < moveChoices.length; i++) {
        moveChoices[i] = new JButton();
        c.gridx = i;
        c.gridy = 1;
        c.weightx=0.5;
        c.weighty=1;
        moveChoices[i].addActionListener(this);
        buttonsPanel.add(moveChoices[i], c);
    }

    moveChoices[0].setText("Rock");
    moveChoices[1].setText("Paper");
    moveChoices[2].setText("Scissors");
    this.add(buttonsPanel);
}

Upvotes: 5

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