JAVA padding string with whitespace (JFrame)
Question
I am writing SWING GUI for some applications. In my application, I have two fields showing some numbers. This is the current result on my JFrame:
12345678 -12,231
1234 -123.000
However, I want it to be like this:
12345678 -12,231
1234 -123.000
I first calculate the length of the first column and pad the whitespace to make the length I want. But the result is the first one I showed above. It seems that different characters occupy different length when displayed on the JFrame. Any idea about this? Or does it have something to do with the font? Thank you!
2 answers
solution1
1 ACCPTED 2013-12-22 20:49:07
Based on the this image
I would suggest the problem you're having is the fact that the font is a variable width font, meaning that each character has it's own width (so 1 is smaller the 2 ).
In this case, you would probably be better of using a GridLayout or GridBagLayout
For example...
JFrame frame = new JFrame("Testing");
frame.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(4, 4, 4, 4);
gbc.anchor = gbc.WEST;
frame.add(new JLabel("12345678"), gbc);
gbc.gridx++;
frame.add(new JLabel("-12,231"), gbc);
gbc.gridy++;
gbc.gridx = 0;
frame.add(new JLabel("1234"), gbc);
gbc.gridx++;
frame.add(new JLabel("-123.000"), gbc);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Or if that's just a little too much, you could just try formating the text as HTML...
JFrame frame = new JFrame("Testing");
frame.setLayout(new BorderLayout());
StringBuilder sb = new StringBuilder(128);
sb.append("<html><table>");
sb.append("<tr><td>12345678</td>-12,231<td></tr>");
sb.append("<tr><td>1234</td>-123.000<td></tr>");
sb.append("</table></html>");
frame.add(new JLabel(sb.toString()));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
Or just use a JTable
solution2
0 2013-12-22 14:58:02
its really easy, take a look:
public static String padRight(String s, int n) {
return String.format("%1$-" + n + "s", s);
}
public static String padLeft(String s, int n) {
return String.format("%1$" + n + "s", s);
}
public static void main(String args[]) throws Exception {
System.out.println(padRight("Howto", 20) + "*");
System.out.println(padLeft("Howto", 20) + "*");
}
/*
output :
Howto *
Howto*
*/
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