File	Doc	Category	Size	Date	Package
JTextArea.java	API Doc	Java SE 5 API	28101	Fri Aug 26 14:57:56 BST 2005	javax.swing

JTextArea

• java.lang.Object
  • java.awt.Component
    • java.awt.Container
      • javax.swing.JComponent
        • javax.swing.text.JTextComponent

DocumentListener myListener = ??;
JTextArea myArea = ??;
myArea.getDocument().addDocumentListener(myListener);

Fields Summary
private static final String	uiClassID
private int	rows
private int	columns
private int	columnWidth
private int	rowHeight
private boolean	wrap
private boolean	word

Constructors Summary
public JTextArea() Constructs a new TextArea. A default model is set, the initial string is null, and rows/columns are set to 0. this(null, null, 0, 0);
public JTextArea(String text) Constructs a new TextArea with the specified text displayed. A default model is created and rows/columns are set to 0. param text the text to be displayed, or null this(null, text, 0, 0);
public JTextArea(int rows, int columns) Constructs a new empty TextArea with the specified number of rows and columns. A default model is created, and the initial string is null. param rows the number of rows >= 0 param columns the number of columns >= 0 exception IllegalArgumentException if the rows or columns arguments are negative. this(null, null, rows, columns);
public JTextArea(String text, int rows, int columns) Constructs a new TextArea with the specified text and number of rows and columns. A default model is created. param text the text to be displayed, or null param rows the number of rows >= 0 param columns the number of columns >= 0 exception IllegalArgumentException if the rows or columns arguments are negative. this(null, text, rows, columns);
public JTextArea(Document doc) Constructs a new JTextArea with the given document model, and defaults for all of the other arguments (null, 0, 0). param doc the model to use this(doc, null, 0, 0);
public JTextArea(Document doc, String text, int rows, int columns) Constructs a new JTextArea with the specified number of rows and columns, and the given model. All of the constructors feed through this constructor. param doc the model to use, or create a default one if null param text the text to be displayed, null if none param rows the number of rows >= 0 param columns the number of columns >= 0 exception IllegalArgumentException if the rows or columns arguments are negative. super(); this.rows = rows; this.columns = columns; if (doc == null) { doc = createDefaultModel(); } setDocument(doc); if (text != null) { setText(text); select(0, 0); } if (rows < 0) { throw new IllegalArgumentException("rows: " + rows); } if (columns < 0) { throw new IllegalArgumentException("columns: " + columns); } LookAndFeel.installProperty(this, "focusTraversalKeysForward", JComponent. getManagingFocusForwardTraversalKeys()); LookAndFeel.installProperty(this, "focusTraversalKeysBackward", JComponent. getManagingFocusBackwardTraversalKeys());

Methods Summary
public void	append(java.lang.String str) Appends the given text to the end of the document. Does nothing if the model is null or the string is null or empty. This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information. param str the text to insert see #insert Document doc = getDocument(); if (doc != null) { try { doc.insertString(doc.getLength(), str, null); } catch (BadLocationException e) { } }
protected javax.swing.text.Document	createDefaultModel() Creates the default implementation of the model to be used at construction if one isn't explicitly given. A new instance of PlainDocument is returned. return the default document model return new PlainDocument();
public javax.accessibility.AccessibleContext	getAccessibleContext() Gets the AccessibleContext associated with this JTextArea. For JTextAreas, the AccessibleContext takes the form of an AccessibleJTextArea. A new AccessibleJTextArea instance is created if necessary. return an AccessibleJTextArea that serves as the AccessibleContext of this JTextArea if (accessibleContext == null) { accessibleContext = new AccessibleJTextArea(); } return accessibleContext;
protected int	getColumnWidth() Gets column width. The meaning of what a column is can be considered a fairly weak notion for some fonts. This method is used to define the width of a column. By default this is defined to be the width of the character m for the font used. This method can be redefined to be some alternative amount. return the column width >= 1 if (columnWidth == 0) { FontMetrics metrics = getFontMetrics(getFont()); columnWidth = metrics.charWidth('m"); } return columnWidth;
public int	getColumns() Returns the number of columns in the TextArea. return number of columns >= 0 return columns;
public int	getLineCount() Determines the number of lines contained in the area. return the number of lines > 0 Element map = getDocument().getDefaultRootElement(); return map.getElementCount();
public int	getLineEndOffset(int line) Determines the offset of the end of the given line. param line the line >= 0 return the offset >= 0 exception BadLocationException Thrown if the line is less than zero or greater or equal to the number of lines contained in the document (as reported by getLineCount). int lineCount = getLineCount(); if (line < 0) { throw new BadLocationException("Negative line", -1); } else if (line >= lineCount) { throw new BadLocationException("No such line", getDocument().getLength()+1); } else { Element map = getDocument().getDefaultRootElement(); Element lineElem = map.getElement(line); int endOffset = lineElem.getEndOffset(); // hide the implicit break at the end of the document return ((line == lineCount - 1) ? (endOffset - 1) : endOffset); }
public int	getLineOfOffset(int offset) Translates an offset into the components text to a line number. param offset the offset >= 0 return the line number >= 0 exception BadLocationException thrown if the offset is less than zero or greater than the document length. Document doc = getDocument(); if (offset < 0) { throw new BadLocationException("Can't translate offset to line", -1); } else if (offset > doc.getLength()) { throw new BadLocationException("Can't translate offset to line", doc.getLength()+1); } else { Element map = getDocument().getDefaultRootElement(); return map.getElementIndex(offset); }
public int	getLineStartOffset(int line) Determines the offset of the start of the given line. param line the line number to translate >= 0 return the offset >= 0 exception BadLocationException thrown if the line is less than zero or greater or equal to the number of lines contained in the document (as reported by getLineCount). int lineCount = getLineCount(); if (line < 0) { throw new BadLocationException("Negative line", -1); } else if (line >= lineCount) { throw new BadLocationException("No such line", getDocument().getLength()+1); } else { Element map = getDocument().getDefaultRootElement(); Element lineElem = map.getElement(line); return lineElem.getStartOffset(); }
public boolean	getLineWrap() Gets the line-wrapping policy of the text area. If set to true the lines will be wrapped if they are too long to fit within the allocated width. If set to false, the lines will always be unwrapped. return if lines will be wrapped return wrap;
public java.awt.Dimension	getPreferredScrollableViewportSize() Returns the preferred size of the viewport if this component is embedded in a JScrollPane. This uses the desired column and row settings if they have been set, otherwise the superclass behavior is used. return The preferredSize of a JViewport whose view is this Scrollable. see JViewport#getPreferredSize Dimension size = super.getPreferredScrollableViewportSize(); size = (size == null) ? new Dimension(400,400) : size; size.width = (columns == 0) ? size.width : columns * getColumnWidth(); size.height = (rows == 0) ? size.height : rows * getRowHeight(); return size;
public java.awt.Dimension	getPreferredSize() Returns the preferred size of the TextArea. This is the maximum of the size needed to display the text and the size requested for the viewport. return the size Dimension d = super.getPreferredSize(); d = (d == null) ? new Dimension(400,400) : d; Insets insets = getInsets(); if (columns != 0) { d.width = Math.max(d.width, columns * getColumnWidth() + insets.left + insets.right); } if (rows != 0) { d.height = Math.max(d.height, rows * getRowHeight() + insets.top + insets.bottom); } return d;
protected int	getRowHeight() Defines the meaning of the height of a row. This defaults to the height of the font. return the height >= 1 if (rowHeight == 0) { FontMetrics metrics = getFontMetrics(getFont()); rowHeight = metrics.getHeight(); } return rowHeight;
public int	getRows() Returns the number of rows in the TextArea. return the number of rows >= 0 return rows;
public boolean	getScrollableTracksViewportWidth() Returns true if a viewport should always force the width of this Scrollable to match the width of the viewport. This is implemented to return true if the line wrapping policy is true, and false if lines are not being wrapped. return true if a viewport should force the Scrollables width to match its own. return (wrap) ? true : super.getScrollableTracksViewportWidth();
public int	getScrollableUnitIncrement(java.awt.Rectangle visibleRect, int orientation, int direction) Components that display logical rows or columns should compute the scroll increment that will completely expose one new row or column, depending on the value of orientation. This is implemented to use the values returned by the getRowHeight and getColumnWidth methods. Scrolling containers, like JScrollPane, will use this method each time the user requests a unit scroll. param visibleRect the view area visible within the viewport param orientation Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL. param direction Less than zero to scroll up/left, greater than zero for down/right. return The "unit" increment for scrolling in the specified direction exception IllegalArgumentException for an invalid orientation see JScrollBar#setUnitIncrement see #getRowHeight see #getColumnWidth switch (orientation) { case SwingConstants.VERTICAL: return getRowHeight(); case SwingConstants.HORIZONTAL: return getColumnWidth(); default: throw new IllegalArgumentException("Invalid orientation: " + orientation); }
public int	getTabSize() Gets the number of characters used to expand tabs. If the document is null or doesn't have a tab setting, return a default of 8. return the number of characters int size = 8; Document doc = getDocument(); if (doc != null) { Integer i = (Integer) doc.getProperty(PlainDocument.tabSizeAttribute); if (i != null) { size = i.intValue(); } } return size;
public java.lang.String	getUIClassID() Returns the class ID for the UI. return the ID ("TextAreaUI") see JComponent#getUIClassID see UIDefaults#getUI return uiClassID;
public boolean	getWrapStyleWord() Gets the style of wrapping used if the text area is wrapping lines. If set to true the lines will be wrapped at word boundaries (ie whitespace) if they are too long to fit within the allocated width. If set to false, the lines will be wrapped at character boundaries. return if the wrap style should be word boundaries instead of character boundaries see #setWrapStyleWord return word;
public void	insert(java.lang.String str, int pos) Inserts the specified text at the specified position. Does nothing if the model is null or if the text is null or empty. This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information. param str the text to insert param pos the position at which to insert >= 0 exception IllegalArgumentException if pos is an invalid position in the model see TextComponent#setText see #replaceRange Document doc = getDocument(); if (doc != null) { try { doc.insertString(pos, str, null); } catch (BadLocationException e) { throw new IllegalArgumentException(e.getMessage()); } }
protected java.lang.String	paramString() Returns a string representation of this JTextArea. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null. return a string representation of this JTextArea. String wrapString = (wrap ? "true" : "false"); String wordString = (word ? "true" : "false"); return super.paramString() + ",colums=" + columns + ",columWidth=" + columnWidth + ",rows=" + rows + ",rowHeight=" + rowHeight + ",word=" + wordString + ",wrap=" + wrapString;
public void	replaceRange(java.lang.String str, int start, int end) Replaces text from the indicated start to end position with the new text specified. Does nothing if the model is null. Simply does a delete if the new string is null or empty. This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information. param str the text to use as the replacement param start the start position >= 0 param end the end position >= start exception IllegalArgumentException if part of the range is an invalid position in the model see #insert see #replaceRange if (end < start) { throw new IllegalArgumentException("end before start"); } Document doc = getDocument(); if (doc != null) { try { if (doc instanceof AbstractDocument) { ((AbstractDocument)doc).replace(start, end - start, str, null); } else { doc.remove(start, end - start); doc.insertString(start, str, null); } } catch (BadLocationException e) { throw new IllegalArgumentException(e.getMessage()); } }
public void	setColumns(int columns) Sets the number of columns for this TextArea. Does an invalidate() after setting the new value. param columns the number of columns >= 0 exception IllegalArgumentException if columns is less than 0 see #getColumns beaninfo description: the number of columns preferred for display int oldVal = this.columns; if (columns < 0) { throw new IllegalArgumentException("columns less than zero."); } if (columns != oldVal) { this.columns = columns; invalidate(); }
public void	setFont(java.awt.Font f) Sets the current font. This removes cached row height and column width so the new font will be reflected, and calls revalidate(). param f the font to use as the current font super.setFont(f); rowHeight = 0; columnWidth = 0;
public void	setLineWrap(boolean wrap) Sets the line-wrapping policy of the text area. If set to true the lines will be wrapped if they are too long to fit within the allocated width. If set to false, the lines will always be unwrapped. A PropertyChange event ("lineWrap") is fired when the policy is changed. By default this property is false. param wrap indicates if lines should be wrapped see #getLineWrap beaninfo preferred: true bound: true description: should lines be wrapped boolean old = this.wrap; this.wrap = wrap; firePropertyChange("lineWrap", old, wrap);
public void	setRows(int rows) Sets the number of rows for this TextArea. Calls invalidate() after setting the new value. param rows the number of rows >= 0 exception IllegalArgumentException if rows is less than 0 see #getRows beaninfo description: the number of rows preferred for display int oldVal = this.rows; if (rows < 0) { throw new IllegalArgumentException("rows less than zero."); } if (rows != oldVal) { this.rows = rows; invalidate(); }
public void	setTabSize(int size) Sets the number of characters to expand tabs to. This will be multiplied by the maximum advance for variable width fonts. A PropertyChange event ("tabSize") is fired when the tab size changes. param size number of characters to expand to see #getTabSize beaninfo preferred: true bound: true description: the number of characters to expand tabs to Document doc = getDocument(); if (doc != null) { int old = getTabSize(); doc.putProperty(PlainDocument.tabSizeAttribute, new Integer(size)); firePropertyChange("tabSize", old, size); }
public void	setWrapStyleWord(boolean word) Sets the style of wrapping used if the text area is wrapping lines. If set to true the lines will be wrapped at word boundaries (whitespace) if they are too long to fit within the allocated width. If set to false, the lines will be wrapped at character boundaries. By default this property is false. param word indicates if word boundaries should be used for line wrapping see #getWrapStyleWord beaninfo preferred: false bound: true description: should wrapping occur at word boundaries boolean old = this.word; this.word = word; firePropertyChange("wrapStyleWord", old, word);
private void	writeObject(java.io.ObjectOutputStream s) See readObject() and writeObject() in JComponent for more information about serialization in Swing. s.defaultWriteObject(); if (getUIClassID().equals(uiClassID)) { byte count = JComponent.getWriteObjCounter(this); JComponent.setWriteObjCounter(this, --count); if (count == 0 && ui != null) { ui.installUI(this); } }