Including linebreak in StringBuilder

Question

I'm having trouble trying to get a linebreak included in a Stringbuilder to appear in a JLabel.

I've found a couple of similar problems solved here, e.g. [here] Problems to linebreak with an int in JLabel and [here] How do I append a newline character for all lines except the last one? , along with a few others but none of them seem to work for me.

When printing to System.out, it works fine and I get a new line each time but when passed to a JLabel, everything appears as one line.

Here's the current version of the code, which has attempted to append a newline character, as well as including one in the main declaration. Neither has any effect when passed to the JLabel:

public void layoutCenter() {
    JPanel central = new JPanel();
    add(central, BorderLayout.CENTER);

    JTabbedPane tabs = new JTabbedPane();
    this.add(tabs);

    // memory tab
    StringBuilder mList = new StringBuilder();
    memLocList = new Memory[MEM_LOCATIONS]; //Memory is a separate class
    for (int i = 0; i < memLocList.length; i++) {
        mList.append("\n");
        memLocList[i] = null;
        mList.append("Memory location: " + i + " " + memLocList[i] + "\n");
    }
    System.out.println(mList.toString());

    JComponent memTab = makeTextPanel(mList.toString());
    tabs.addTab("Memory", memTab);

}

protected JComponent makeTextPanel(String text) {
    JPanel panel = new JPanel(false);
    JLabel filler = new JLabel(text);
    panel.add(filler);
    return panel;
}

I've also tried using System.getProperty(line.separator) with similar results and can't think of anything else to try so thought I'd appeal for help here.

Thanks, Robert.

-EDIT-

Thanks to mKorbel, changing the JLabel to a JTextPane solved it. The two lines in question are:

JTextPane filler = new JTextPane();
    filler.setText(text);

Thanks again to everyone.

possible duplicate of [Newline in JLabel](http://stackoverflow.com/questions/1090098/newline-in-jlabel) — Piotr Praszmo, Jun 26 '12 at 13:13

score 2 · Answer 1 · answered Jun 26 '12 at 13:13

2

You're going to have to use <html> and <br> to get line breaks in a JLabel Swing component.

answered Jun 26 '12 at 13:13

Gilbert Le Blanc

50,182
6
67
111

Thanks Gilbert, I already tried using this: mList.append("Memory location: " + i + " " + memLocList[i] + "
"); but no luck with that either. – Robert Jun 26 '12 at 13:18
@Robert: Maybe I'm not understanding what you wrote, but you have no text after the break. – Gilbert Le Blanc Jun 26 '12 at 13:21
@ Gilbert: Sorry, my additional comment isn't very clear. It's part of a loop and I wanted a line-break after each iteration. – Robert Jun 26 '12 at 13:40
@Robert: Ok. A JTextPane is more appropriate for what you want, as you commented. – Gilbert Le Blanc Jun 26 '12 at 13:42

score 2 · Answer 2 · answered Jun 26 '12 at 13:13

2

If you absolutely must use JLabel, then I suggest using one for each line.

answered Jun 26 '12 at 13:13

Radu Murzea

10,724
10
47
69

score 2 · Answer 3 · answered Jun 26 '12 at 13:16

2

You can make a JLabel have mulitple lines by wrapping the text in HTML tags and using br tags to add a new line.

If you news auto wrapping I suggest using a JTexrArea. You can make it uneditable and style it so it looks like a label.

answered Jun 26 '12 at 13:16

Jeff Storey

56,312
72
233
406

score 2 · Accepted Answer · answered Jun 26 '12 at 13:17

2

JLabel isn't designated to held multilines document, there are two choices (by accepting newline or tab by default)

if document could not be decorated or styled somehow then to use JTextArea
in the case document could be decorated or styled somehow then to use JEditorPane or JTextPane

answered Jun 26 '12 at 13:17

mKorbel

109,525
20
134
319

Thank you mKorbel, I changed it to JTextpane and it now formats correctly. Much appreciated. – Robert Jun 26 '12 at 13:27
As an aside, although this works very well, it takes a while to start up. Is there a more efficient way of doing this? (without the obvious, "don't use Java.") – Robert Jun 26 '12 at 19:33
the same start_up became from all programing languages, plus minus citibus, – mKorbel Jun 26 '12 at 19:48

score 2 · Answer 5 · answered Jun 26 '12 at 13:27

2

You can look at this tutorial: http://docs.oracle.com/javase/tutorial/uiswing/components/html.html

One of the example is using html to make it two lines for a JButton text. It should be very similar.

answered Jun 26 '12 at 13:27

evanwong

5,054
3
31
44

Including linebreak in StringBuilder

5 Answers5