Java examples for Swing:JTextArea
Install Document filter for text area
/*//from www .j av a 2 s.c om * TextComponentDemo.java requires one additional file: * DocumentSizeFilter.java */ import java.awt.*; import java.awt.event.*; import java.util.HashMap; import javax.swing.*; import javax.swing.text.*; import javax.swing.event.*; import javax.swing.undo.*; /* A 1.4 class used by TextComponentDemo.java. */ import javax.swing.*; import javax.swing.text.*; import java.awt.Toolkit; class DocumentSizeFilter extends DocumentFilter { int maxCharacters; boolean DEBUG = false; public DocumentSizeFilter(int maxChars) { maxCharacters = maxChars; } public void insertString(FilterBypass fb, int offs, String str, AttributeSet a) throws BadLocationException { if (DEBUG) { System.out .println("in DocumentSizeFilter's insertString method"); } //This rejects the entire insertion if it would make //the contents too long. Another option would be //to truncate the inserted string so the contents //would be exactly maxCharacters in length. if ((fb.getDocument().getLength() + str.length()) <= maxCharacters) super.insertString(fb, offs, str, a); else Toolkit.getDefaultToolkit().beep(); } public void replace(FilterBypass fb, int offs, int length, String str, AttributeSet a) throws BadLocationException { if (DEBUG) { System.out.println("in DocumentSizeFilter's replace method"); } //This rejects the entire replacement if it would make //the contents too long. Another option would be //to truncate the replacement string so the contents //would be exactly maxCharacters in length. if ((fb.getDocument().getLength() + str.length() - length) <= maxCharacters) super.replace(fb, offs, length, str, a); else Toolkit.getDefaultToolkit().beep(); } } public class TextComponentDemo extends JFrame { JTextPane textPane; AbstractDocument doc; static final int MAX_CHARACTERS = 300; JTextArea changeLog; String newline = "\n"; HashMap<Object, Action> actions; //undo helpers protected UndoAction undoAction; protected RedoAction redoAction; protected UndoManager undo = new UndoManager(); public TextComponentDemo() { super("TextComponentDemo"); //Create the text pane and configure it. textPane = new JTextPane(); textPane.setCaretPosition(0); textPane.setMargin(new Insets(5, 5, 5, 5)); StyledDocument styledDoc = textPane.getStyledDocument(); if (styledDoc instanceof AbstractDocument) { doc = (AbstractDocument) styledDoc; doc.setDocumentFilter(new DocumentSizeFilter(MAX_CHARACTERS)); } else { System.err .println("Text pane's document isn't an AbstractDocument!"); System.exit(-1); } JScrollPane scrollPane = new JScrollPane(textPane); scrollPane.setPreferredSize(new Dimension(200, 200)); //Create the text area for the status log and configure it. changeLog = new JTextArea(5, 30); changeLog.setEditable(false); JScrollPane scrollPaneForLog = new JScrollPane(changeLog); //Create a split pane for the change log and the text area. JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, scrollPane, scrollPaneForLog); splitPane.setOneTouchExpandable(true); //Create the status area. JPanel statusPane = new JPanel(new GridLayout(1, 1)); CaretListenerLabel caretListenerLabel = new CaretListenerLabel( "Caret Status"); statusPane.add(caretListenerLabel); //Add the components. getContentPane().add(splitPane, BorderLayout.CENTER); getContentPane().add(statusPane, BorderLayout.PAGE_END); //Set up the menu bar. actions = createActionTable(textPane); JMenu editMenu = createEditMenu(); JMenu styleMenu = createStyleMenu(); JMenuBar mb = new JMenuBar(); mb.add(editMenu); mb.add(styleMenu); setJMenuBar(mb); //Add some key bindings. addBindings(); //Put the initial text into the text pane. initDocument(); textPane.setCaretPosition(0); //Start watching for undoable edits and caret changes. doc.addUndoableEditListener(new MyUndoableEditListener()); textPane.addCaretListener(caretListenerLabel); doc.addDocumentListener(new MyDocumentListener()); } //This listens for and reports caret movements. protected class CaretListenerLabel extends JLabel implements CaretListener { public CaretListenerLabel(String label) { super(label); } //Might not be invoked from the event dispatch thread. public void caretUpdate(CaretEvent e) { displaySelectionInfo(e.getDot(), e.getMark()); } //This method can be invoked from any thread. It //invokes the setText and modelToView methods, which //must run on the event dispatch thread. We use //invokeLater to schedule the code for execution //on the event dispatch thread. protected void displaySelectionInfo(final int dot, final int mark) { SwingUtilities.invokeLater(new Runnable() { public void run() { if (dot == mark) { // no selection try { Rectangle caretCoords = textPane .modelToView(dot); //Convert it to view coordinates. setText("caret: text position: " + dot + ", view location = [" + caretCoords.x + ", " + caretCoords.y + "]" + newline); } catch (BadLocationException ble) { setText("caret: text position: " + dot + newline); } } else if (dot < mark) { setText("selection from: " + dot + " to " + mark + newline); } else { setText("selection from: " + mark + " to " + dot + newline); } } }); } } //This one listens for edits that can be undone. protected class MyUndoableEditListener implements UndoableEditListener { public void undoableEditHappened(UndoableEditEvent e) { //Remember the edit and update the menus. undo.addEdit(e.getEdit()); undoAction.updateUndoState(); redoAction.updateRedoState(); } } //And this one listens for any changes to the document. protected class MyDocumentListener implements DocumentListener { public void insertUpdate(DocumentEvent e) { displayEditInfo(e); } public void removeUpdate(DocumentEvent e) { displayEditInfo(e); } public void changedUpdate(DocumentEvent e) { displayEditInfo(e); } private void displayEditInfo(DocumentEvent e) { Document document = e.getDocument(); int changeLength = e.getLength(); changeLog.append(e.getType().toString() + ": " + changeLength + " character" + ((changeLength == 1) ? ". " : "s. ") + " Text length = " + document.getLength() + "." + newline); } } //Add a couple of emacs key bindings for navigation. protected void addBindings() { InputMap inputMap = textPane.getInputMap(); //Ctrl-b to go backward one character KeyStroke key = KeyStroke.getKeyStroke(KeyEvent.VK_B, Event.CTRL_MASK); inputMap.put(key, DefaultEditorKit.backwardAction); //Ctrl-f to go forward one character key = KeyStroke.getKeyStroke(KeyEvent.VK_F, Event.CTRL_MASK); inputMap.put(key, DefaultEditorKit.forwardAction); //Ctrl-p to go up one line key = KeyStroke.getKeyStroke(KeyEvent.VK_P, Event.CTRL_MASK); inputMap.put(key, DefaultEditorKit.upAction); //Ctrl-n to go down one line key = KeyStroke.getKeyStroke(KeyEvent.VK_N, Event.CTRL_MASK); inputMap.put(key, DefaultEditorKit.downAction); } //Create the edit menu. protected JMenu createEditMenu() { JMenu menu = new JMenu("Edit"); //Undo and redo are actions of our own creation. undoAction = new UndoAction(); menu.add(undoAction); redoAction = new RedoAction(); menu.add(redoAction); menu.addSeparator(); //These actions come from the default editor kit. //Get the ones we want and stick them in the menu. menu.add(getActionByName(DefaultEditorKit.cutAction)); menu.add(getActionByName(DefaultEditorKit.copyAction)); menu.add(getActionByName(DefaultEditorKit.pasteAction)); menu.addSeparator(); menu.add(getActionByName(DefaultEditorKit.selectAllAction)); return menu; } //Create the style menu. protected JMenu createStyleMenu() { JMenu menu = new JMenu("Style"); Action action = new StyledEditorKit.BoldAction(); action.putValue(Action.NAME, "Bold"); menu.add(action); action = new StyledEditorKit.ItalicAction(); action.putValue(Action.NAME, "Italic"); menu.add(action); action = new StyledEditorKit.UnderlineAction(); action.putValue(Action.NAME, "Underline"); menu.add(action); menu.addSeparator(); menu.add(new StyledEditorKit.FontSizeAction("12", 12)); menu.add(new StyledEditorKit.FontSizeAction("14", 14)); menu.add(new StyledEditorKit.FontSizeAction("18", 18)); menu.addSeparator(); menu.add(new StyledEditorKit.FontFamilyAction("Serif", "Serif")); menu.add(new StyledEditorKit.FontFamilyAction("SansSerif", "SansSerif")); menu.addSeparator(); menu.add(new StyledEditorKit.ForegroundAction("Red", Color.red)); menu.add(new StyledEditorKit.ForegroundAction("Green", Color.green)); menu.add(new StyledEditorKit.ForegroundAction("Blue", Color.blue)); menu.add(new StyledEditorKit.ForegroundAction("Black", Color.black)); return menu; } protected void initDocument() { String initString[] = { "Use the mouse to place the caret.", "Use the edit menu to cut, copy, paste, and select text.", "Also to undo and redo changes.", "Use the style menu to change the style of the text.", "Use the arrow keys on the keyboard or these emacs key bindings to move the caret:", "Ctrl-f, Ctrl-b, Ctrl-n, Ctrl-p." }; SimpleAttributeSet[] attrs = initAttributes(initString.length); try { for (int i = 0; i < initString.length; i++) { doc.insertString(doc.getLength(), initString[i] + newline, attrs[i]); } } catch (BadLocationException ble) { System.err.println("Couldn't insert initial text."); } } protected SimpleAttributeSet[] initAttributes(int length) { //Hard-code some attributes. SimpleAttributeSet[] attrs = new SimpleAttributeSet[length]; attrs[0] = new SimpleAttributeSet(); StyleConstants.setFontFamily(attrs[0], "SansSerif"); StyleConstants.setFontSize(attrs[0], 16); attrs[1] = new SimpleAttributeSet(attrs[0]); StyleConstants.setBold(attrs[1], true); attrs[2] = new SimpleAttributeSet(attrs[0]); StyleConstants.setItalic(attrs[2], true); attrs[3] = new SimpleAttributeSet(attrs[0]); StyleConstants.setFontSize(attrs[3], 20); attrs[4] = new SimpleAttributeSet(attrs[0]); StyleConstants.setFontSize(attrs[4], 12); attrs[5] = new SimpleAttributeSet(attrs[0]); StyleConstants.setForeground(attrs[5], Color.red); return attrs; } //The following two methods allow us to find an //action provided by the editor kit by its name. private HashMap<Object, Action> createActionTable( JTextComponent textComponent) { HashMap<Object, Action> actions = new HashMap<Object, Action>(); Action[] actionsArray = textComponent.getActions(); for (int i = 0; i < actionsArray.length; i++) { Action a = actionsArray[i]; actions.put(a.getValue(Action.NAME), a); } return actions; } private Action getActionByName(String name) { return actions.get(name); } class UndoAction extends AbstractAction { public UndoAction() { super("Undo"); setEnabled(false); } public void actionPerformed(ActionEvent e) { try { undo.undo(); } catch (CannotUndoException ex) { System.out.println("Unable to undo: " + ex); ex.printStackTrace(); } updateUndoState(); redoAction.updateRedoState(); } protected void updateUndoState() { if (undo.canUndo()) { setEnabled(true); putValue(Action.NAME, undo.getUndoPresentationName()); } else { setEnabled(false); putValue(Action.NAME, "Undo"); } } } class RedoAction extends AbstractAction { public RedoAction() { super("Redo"); setEnabled(false); } public void actionPerformed(ActionEvent e) { try { undo.redo(); } catch (CannotRedoException ex) { System.out.println("Unable to redo: " + ex); ex.printStackTrace(); } updateRedoState(); undoAction.updateUndoState(); } protected void updateRedoState() { if (undo.canRedo()) { setEnabled(true); putValue(Action.NAME, undo.getRedoPresentationName()); } else { setEnabled(false); putValue(Action.NAME, "Redo"); } } } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event dispatch thread. */ private static void createAndShowGUI() { //Create and set up the window. final TextComponentDemo frame = new TextComponentDemo(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Display the window. frame.pack(); frame.setVisible(true); } //The standard main method. public static void main(String[] args) { //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. SwingUtilities.invokeLater(new Runnable() { public void run() { //Turn off metal's use of bold fonts UIManager.put("swing.boldMetal", Boolean.FALSE); createAndShowGUI(); } }); } } /* * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Oracle or the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */