Develop Reference

How do I add text to a JTextArea?

I'm making a java Text Editior and I can't seems to know how to insert a line of text that is "[code][/code]" Here is what I'm trying to program. The method for the inserting is called "insert". So it has to be something that is insert,(something that inserts strings of text in JTextArea)
/////////////////// CODE //////////////////////////////////////////////////////////////////////////////////////////////////
this.insert.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
/////////////// END OF CODE ///////////////////////////////////////////////////////////////////

Simple example to set/assign text to JTextArea .. this is not the solution but it will help you...
JTextArea textArea = new JTextArea(
"This is an editable JTextArea. " +
"A text area is a \"plain\" text component, " +
"which means that although it can display text " +
"in any font, all of the text is in the same font."
);
textArea.setFont(new Font("Serif", Font.ITALIC, 16));
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
Although to set the text .. use this method
void insert(String str, int pos)
Inserts the specified text at the specified position.
public void setText(String t)
Sets the text of JTextArea
For refrerence and help please follow jtextareaguide
Link to video tutorial
Guide for Simple Editor in Java

Java already provides a method for inserting text in the JTextArea class. Try this...
JTextArea t = new JTextArea();
t.setText("specified string");
t.append("+ added string");

use:
JTextArea text=new JTextArea();
text.setText("Message..");
Here is a doc.
public class JTextArea extends JTextComponent
A JTextArea is a multi-line area that displays plain text. It is intended to be a lightweight component that provides source compatibility with the java.awt.TextArea class where it can reasonably do so. You can find information and examples of using all the text components in Using Text Components, a section in The Java Tutorial.

Try this:
JTextArea textj1 = new JTextArea();
textj1.setText(textj1.getText().trim() + "a string or even an arraylist");

Better using:
textArea.setText(textArea.getText()+" Message");

Including linebreak in StringBuilder

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.

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

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

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

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.

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.

How do I underline text "text" when text is a field?

public class Text extends JPanel {
private String text;
public Text()
{
this.setPreferredSize(new Dimension(20,20));
setFont (new Font(text, Font.PLAIN, 24));
text = "";
}
public void showUnderline()
{
Hashtable<TextAttribute, Object> map = new Hashtable
<TextAttribute, Object>();
map.put(TextAttribute.UNDERLINE, TextAttribute.UNDERLINE_ON);
}
the text object will be created within another class. in that class I will need to underline it with the showUnderline method. The method seems incomplete.I'm shooting for the java exclusive approach, meaning no HTML.
How do I link the text to the showUnderline method?

What do you mean 'java exclusive approach, meaning no HTML' ? You probably are looking for a JLabel, and you can put very simple html in it. Here's the first result on google:
http://www.apl.jhu.edu/~hall/java/Swing-Tutorial/Swing-Tutorial-JLabel.html
It has an example of making text different colors, fonts, and bold or italicized. You could probably just do something like:
JLabel label = new JLabel("<u>MY TEXT</u>",JLabel.CENTER);
From there, you can place it like you would place any other JComponent.
If you really don't want HTML, you could use a JTextPane. Here's an example:
http://www.exampledepot.com/egs/javax.swing.text/style_hilitewords2.html

Text align in JLabel [duplicate]

This question already has answers here:
Align text in JLabel to the right
(3 answers)
Closed 9 years ago.
I've got GridLayout-JPanel. In every cell there is a JLabel with some String. How can I right-align this text in my cells?

#Noran In response to your comment on #mre's answer, you could initialize all the JLabels into an array. Then, all you'd have to do is loop through the array and set the alignment that way.
for (JLabel label: arrayOfJLabels) {
label.setHorizontalAlignment(SwingConstants.LEFT);
}

A couple JLabel constructors take horizontal alignment arguments. These constants are inherited from SwingConstants.

I have read your question and I have a suggestion. There are a few methods to fulfill your requirement. Since you didn't mention the exact requirement, I can give you a simple example as I understand it:
//create a JLabel and name it as jLabel2
javax.swing.JLabel jLabel2 = new javax.swing.JLabel();
jLabel2.setText("Dehans Label");
jLabel2.setHorizontalTextPosition(javax.swing.SwingConstants.RIGHT);
Please refer following methods # JLabel class in JavaSE API through following links:
public void setHorizontalAlignment(int alignment)
public void
setVerticalAlignment(int alignment)
public void
setVerticalTextPosition(int textPosition)

Selecting text from a JLabel?

Is it possible to enable the selection of text from a JLabel? If not, what's the best alternative control to use, and how can it be configured to appear like a JLabel?

A JTextField doesn't allow html-formatted text like a JLabel. If you want selectable html text you could alternatively try a JTextPane set to html formatting:
JTextPane f = new JTextPane();
f.setContentType("text/html"); // let the text pane know this is what you want
f.setText("<html>Hello World</html>"); // showing off
f.setEditable(false); // as before
f.setBackground(null); // this is the same as a JLabel
f.setBorder(null); // remove the border

You can use a JTextField without enabling the editing
JTextField f=new JTextField("Hello World");
f.setEditable(false);
content.add(f);
Pierre

Building on the answers:
You can use a JTextField without enabling the editing
JTextField f=new JTextField("Hello World");
f.setEditable(false);
f.setBackground(null); //this is the same as a JLabel
f.setBorder(null); //remove the border
I don't know how to stop the text from "Jumping" when you select it, or replace the text (programmatically). Maybe it is just my computer...

When using JTextField, you will also want to remove the border:
f.setBorder(null);
and set the disabled text color: f.setDisabledTextColor(Color.black);

As variant below CopyableLabel supports html tags and Fonts as JLabel.
public class CopyableLabel extends JTextPane {
private static final long serialVersionUID = -1;
private static final Font DEFAULT_FONT;
static {
Font font = UIManager.getFont("Label.font");
DEFAULT_FONT = (font != null) ? font: new Font("Tahoma", Font.PLAIN, 11);
}
public CopyableLabel() {
construct();
}
private void construct() {
setContentType("text/html");
setEditable(false);
setBackground(null);
setBorder(null);
putClientProperty(JEditorPane.HONOR_DISPLAY_PROPERTIES, true);
setFont(DEFAULT_FONT);
}
}

JLabels cannot be editable.
However, you could use a JTextField and just change the foreground / background colors to make it appear as a JLabel. If you wanted to be really fancy you could add code to change the colors when it's selected to indicate that it's editable.

Besides the changes suggested in other responses (setEditable, setContentType, setOpaque or setBackground, maybe setEnabled + setDisabledTextColor(Color.black), maybe setBorder(null) and/or setMargin(new Insets(0,0,0,0))
To get the font of a JTextPane to look like a JLabel, see the suggestion from this blog post:
"Unfortunately, simply calling set font on JEditorPane will have no effect, as the default font is pulled from a style sheet rather than the JComponent. There is, however, a clever way around the errant font default. The best way to change the default font in an HTML rendering JEditorPane, is to alter the style sheet like this:"
// create a JEditorPane that renders HTML and defaults to the system font.
JEditorPane editorPane =
new JEditorPane(new HTMLEditorKit().getContentType(),text);
// set the text of the JEditorPane to the given text.
editorPane.setText(text);
// add a CSS rule to force body tags to use the default label font
// instead of the value in javax.swing.text.html.default.csss
Font font = UIManager.getFont("Label.font");
String bodyRule = "body { font-family: " + font.getFamily() + "; " +
"font-size: " + font.getSize() + "pt; }";
((HTMLDocument)editorPane.getDocument()).getStyleSheet().addRule(bodyRule);