BoxLayout ignores setYAlighment

Question

Here is a function:

/**
 * Creates an instance of a JLabel with the given arguments
 * @param text The text to be displayed on the Label
 * @param font The font of the label
 * @param bold set to true if you want the label's text to be bold
 * @param fontSize The size of the font to be rendered
 * @param alignment An alignment (E.g. CENTER_ALIGNMENT)
 * @param verticleAlignment an optional argument to allow one to choose the Y alignment
 * **/
public JLabel createLabel(String text, String font, boolean bold, int fontSize, float alignment, float...verticleAlignment){
    JLabel label = new JLabel(text);
    label.setFont(new Font(font, bold ? Font.BOLD : Font.PLAIN, fontSize));


    label.setAlignmentX(alignment);
    if(verticleAlignment.length > 0){
        label.setAlignmentY(verticleAlignment[0]);
    }
    return label;
}

For some reason, no matter what I enter in the varArg verticleAlignment, it doesn't actually apply?

add(createLabel("ChatBytes™ - Do not steal.", "Arial", false, 12, CENTER_ALIGNMENT, BOTTOM_ALIGNMENT));

Can anyone see a reason why it would ignore the setYAlignment part of my function?

This is how it renders

Read [Fixing Alignment Problems](http://docs.oracle.com/javase/tutorial/uiswing/layout/box.html#alignment) from the Swing tutorial on `Using Box Layout` for a detailed explanation on how alignment works. If you still need help then post a `SSCCE` that demonstrates the problem. — camickr, Sep 11 '13 at 15:16
I'll read up on that, can you explain the acronym SSCCE please? — Shaun Wild, Sep 11 '13 at 15:17
This question has annoyed, what an uneasy bunch of people I've been unfortunate enough to have stumble upon my question. I've found the answer now. — Shaun Wild, Sep 14 '13 at 16:18

score 5 · Answer 1 · edited May 23 '17 at 12:19

As an alternative, consider a nested layout. In the example below, the relevant label is added to the SOUTH area of a BorderLayout, the default for JFrame, and a placeholder for your login panel is added to CENTER. Examine the resize behavior of each approach for suitability.

Addendum: I hope to [learn] why the setAlignmentY() is being ignored.

As noted in How to Use BoxLayout: Box Layout Features, "When a BoxLayout lays out components from top to bottom, … any extra space appears at the bottom of the container." This explains your original observation and correct solution.

In the API, note that setAlignmentX() "Sets the the vertical alignment," and setAlignmentY() "Sets the the horizontal alignment." In this context, vertical means the vertical axis of a top-to-bottom layout, such as BoxLayout.Y_AXIS, while horizontal means the horizontal axis of a left-to-right layout, such as BoxLayout.X_AXIS. In How to Use BoxLayout: Fixing Alignment Problems, BoxAlignmentDemo contrasts the two. In a left-to-right layout, pictured below, setAlignmentY() is used to adjust vertical positioning relative to the horizontal layout axis. In a top-to-bottom layout, such as yours, setAlignmentY() simply has no effect.

setAlignmentY

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Font;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

/** @see https://stackoverflow.com/a/18805146/230513 */
public class Test {

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(createLogin(), BorderLayout.CENTER);
        JLabel admonition = new JLabel("ChatBytes™—Do not steal.", JLabel.CENTER);
        f.add(admonition, BorderLayout.SOUTH);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static JPanel createLogin() {
        JPanel p = new JPanel();
        p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
        JLabel label = new JLabel("Existing CHATBYTES login panel.");
        label.setFont(label.getFont().deriveFont(Font.ITALIC, 24f));
        label.setAlignmentX(0.5f);
        label.setBorder(new EmptyBorder(0, 20, 0, 20));
        p.add(Box.createVerticalStrut(36));
        p.add(label);
        p.add(Box.createVerticalStrut(144));
        return p;
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Test().display();
            }
        });
    }
}

score 3 · Accepted Answer · answered Sep 14 '13 at 16:19

3

use

    add(Box.createVerticalGlue());

to create a vertical space that pushes the component to the bottom of the JFrame

answered Sep 14 '13 at 16:19

Shaun Wild

1,237
3
17
34

+1 for `createVerticalGlue()`; please consider adding an [sscce](http://sscce.org/) that shows your approach, such as the one shown [here](http://stackoverflow.com/a/18805146/230513). – trashgod Sep 14 '13 at 18:42

BoxLayout ignores setYAlighment

2 Answers2

Linked

Related