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Java Forum / GUI / May 2008How to display text messages in a scrolling text area?
To display text messages (as - for example - in a window with log messages) in a scrolling text area, there are several Swing components I am aware of: http://download.java.net/jdk7/docs/api/javax/swing/JTextArea.html http://download.java.net/jdk7/docs/api/javax/swing/JTextPane.html http://download.java.net/jdk7/docs/api/javax/swing/JEditorPane.html I might want to subclass one of them for my »log area«. While I only think of plain text output now, more features, such as different typefaces or text colors might come in handy later. I also might want to use one of them in teaching, when showing how to display log messages in a GUI. It seems that JEditorPane has more features than the other two. So should I always use JEditorPane for such purposes, or are there any reasons to use one of JTextArea or JTextPane sometimes? > To display text messages (as - for example - in a window with > log messages) in a scrolling text area, there are several [quoted text clipped - 7 lines] > I only think of plain text output now, more features, such as > different typefaces or text colors might come in handy later. What about tabular log data? <http://download.java.net/jdk7/docs/api/javax/swing/JTable.html> > I also might want to use one of them in teaching, when showing > how to display log messages in a GUI. Follow the lesson plan? Is this CS2101 The Java Language, or CS2202 Java Swing GUIs > It seems that JEditorPane has more features than the other two. > So should I always use JEditorPane for such purposes, or are there > any reasons to use one of JTextArea or JTextPane sometimes? JTextArea has .getLineCount() JEditorPane has .getHyperlinkListeners() JTextPane has .insertComponent(Component c) >Follow the lesson plan? >Is this CS2101 The Java Language, or CS2202 Java Swing GUIs I am giving adult evening classes and am solely responsible for the lesson plan, so I do not have to follow anyone's lesson plan and can fit my own lesson plan to the interests and capabilities of the adult pupils of this adult education center. They are often beginners, and I do not have to treat a certain set of topics, so instead of giving an overview, I have chosen to teach just a few of the most fundamental aspects of the language, but then use enough time for each of those topics to do exercises until nearly everyone is able to apply it. My classes advance quite slowly and do cover only a small part of the language, but a high percentage of the pupils who attend the class will understand most of it, even if this is their first programming language. I will have a look at CS2101 and CS2202. >>Follow the lesson plan? >>Is this CS2101 The Java Language, or CS2202 Java Swing GUIs [quoted text clipped - 4 lines] > and capabilities of the adult pupils of this adult education > center. Maybe I should have said, The example code and assignments you provide your class should follow the lesson plan. Do you want to have your students learn how to transform logger output to styled text so that it may displayed in a styled text component? From my experience there is no greater hindrance to learning than unfocused examples and assignments. For a example of a piss-poor and unfocused assignment see the Purse and Coins assignment in a recent c.l.j.? group discussion. > They are often beginners, and I do not have to treat a certain > set of topics, so instead of giving an overview, I have chosen [quoted text clipped - 8 lines] > > I will have a look at CS2101 and CS2202. >to have your students learn how to transform logger output to >styled text so that it may displayed in a styled text component? I need to estimate which applications of GUIs and Swing are most common, to teach only these, because it would not make sense to start with components needed only rarely. I estimate that many GUI programs need to output text reports to the user. Therefore, I want to show how to do this using a multi-line text component. Since the time constraints only allow for a single multi-line text component, I wonder which of JTextArea, JTextPane, and JEditorPane to use for this purpose. >JTextArea has .getLineCount() OK, thanks! Apart from this operation it seems that overall JEditorPane and JTextPane are more powerful and high-level and thus often more simple to use than JTextArea. So it seems that usually to display text one would prefer JEditorPane or JTextPane. I still would appreciate if someone knew even other examples than obtaining a count of lines for when to prefer JTextArea. >>JTextArea has .getLineCount() > > OK, thanks! Apart from this operation it seems that > overall JEditorPane and JTextPane are more powerful and > high-level and thus often more simple to use than JTextArea. quoting from The Java Tutorials - Using Text Components (JEditorPane - JTextPane)... "are powerful and multi-faceted components suitable for high-end needs, and offer more avenues for customization than the other text components. Because they are so powerful and flexible, styled text components typically require more initial programming to set up and use. One exception is that editor panes can be easily loaded with formatted text from a URL, which makes them useful for displaying uneditable help information." > So it seems that usually to display text one would prefer > JEditorPane or JTextPane. I still would appreciate if someone > knew even other examples than obtaining a count of lines > for when to prefer JTextArea. Prefer JTextArea for multi-line unstyled text. >than the other text components. Because they are so powerful and flexible, >styled text components typically require more initial programming to set >up and use. A JTextArea also has some more difficult aspects. For example, when one wants a line appended at the end to be visible (a common case), with a JTextArea in a JScrollpane, sometimes one needs to call »scrollRectToVisible« with the offset of the last line, so one needs to call »getLineEndOffset(line)«, which sometimes might throw a BadLocationException, which also needs to be handled. But such boilerplate code does not matter that much when one is subclassing to get a custom log text area component from a Swing text component, because it all can be written once and then be hidden behind methods of the custom log component. >Prefer JTextArea for multi-line unstyled text. JTextPane and JEditorPane also allow multi-line unstyled text, and when subclassing to get a custom log text window, boilerplate code needs only be written once (actually just copied from tutorials), so the difficulty to use does not matter that much. So I wonder, whether from the point of visible properties of the product (what one observes when the program with the log window is running), there would ever be a reason to prefer JTextArea above JTextPane or JEditorPane. For example, if JTextPane would be known to be slower than JTextArea, this would be such a reason. > To display text messages (as - for example - in a window with > log messages) in a scrolling text area, there are several > Swing components I am aware of: Another way is with a JTree. Your treemodel need not keep all non-visible messages in RAM. See http://mindprod.com/jgloss/jtree.html  SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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