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.
*
*
* This component has capabilities not found in the
* java.awt.TextArea class. The superclass should be
* consulted for additional capabilities.
* Alternative multi-line text classes with
* more capabilities are JTextPane and JEditorPane.
*
* The java.awt.TextArea internally handles scrolling.
* JTextArea is different in that it doesn't manage scrolling,
* but implements the swing Scrollable interface. This allows it
* to be placed inside a JScrollPane if scrolling
* behavior is desired, and used directly if scrolling is not desired.
*
* The java.awt.TextArea has the ability to do line wrapping.
* This was controlled by the horizontal scrolling policy. Since
* scrolling is not done by JTextArea directly, backward
* compatibility must be provided another way. JTextArea has
* a bound property for line wrapping that controls whether or
* not it will wrap lines. By default, the line wrapping property
* is set to false (not wrapped).
*
* java.awt.TextArea has two properties rows
* and columns that are used to determine the preferred size.
* JTextArea uses these properties to indicate the
* preferred size of the viewport when placed inside a JScrollPane
* to match the functionality provided by java.awt.TextArea.
* JTextArea has a preferred size of what is needed to
* display all of the text, so that it functions properly inside of
* a JScrollPane. If the value for rows
* or columns is equal to zero,
* the preferred size along that axis is used for
* the viewport preferred size along the same axis.
*
* The java.awt.TextArea could be monitored for changes by adding
* a TextListener for TextEvents.
* In the JTextComponent based
* components, changes are broadcasted from the model via a
* DocumentEvent to DocumentListeners.
* The DocumentEvent gives
* the location of the change and the kind of change if desired.
* The code fragment might look something like:
*
* DocumentListener myListener = ??; * JTextArea myArea = ??; * myArea.getDocument().addDocumentListener(myListener); **
*
* Warning: Swing is not thread safe. For more * information see Swing's Threading * Policy. *
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*
* @beaninfo
* attribute: isContainer false
* description: A multi-line area that displays plain text.
*
* @author Timothy Prinzing
* @see JTextPane
* @see JEditorPane
*/
public class JTextArea extends JTextComponent {
/**
* @see #getUIClassID
* @see #readObject
*/
private static final String uiClassID = "TextAreaUI";
/**
* Constructs a new TextArea. A default model is set, the initial string
* is null, and rows/columns are set to 0.
*/
public JTextArea() {
this(null, null, 0, 0);
}
/**
* 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
*/
public JTextArea(String text) {
this(null, text, 0, 0);
}
/**
* 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.
*/
public JTextArea(int rows, int columns) {
this(null, null, rows, 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.
*/
public JTextArea(String text, int rows, int columns) {
this(null, text, rows, columns);
}
/**
* 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
*/
public JTextArea(Document doc) {
this(doc, null, 0, 0);
}
/**
* 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.
*/
public JTextArea(Document doc, String text, int rows, int columns) {
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());
}
/**
* Returns the class ID for the UI.
*
* @return the ID ("TextAreaUI")
* @see JComponent#getUIClassID
* @see UIDefaults#getUI
*/
public String getUIClassID() {
return uiClassID;
}
/**
* 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
*/
protected Document createDefaultModel() {
return new PlainDocument();
}
/**
* 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
*/
public void setTabSize(int size) {
Document doc = getDocument();
if (doc != null) {
int old = getTabSize();
doc.putProperty(PlainDocument.tabSizeAttribute, Integer.valueOf(size));
firePropertyChange("tabSize", old, size);
}
}
/**
* 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
*/
public int getTabSize() {
int size = 8;
Document doc = getDocument();
if (doc != null) {
Integer i = (Integer) doc.getProperty(PlainDocument.tabSizeAttribute);
if (i != null) {
size = i.intValue();
}
}
return size;
}
/**
* 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
*/
public void setLineWrap(boolean wrap) {
boolean old = this.wrap;
this.wrap = wrap;
firePropertyChange("lineWrap", old, wrap);
}
/**
* 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
*/
public boolean getLineWrap() {
return wrap;
}
/**
* 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
*/
public void setWrapStyleWord(boolean word) {
boolean old = this.word;
this.word = word;
firePropertyChange("wrapStyleWord", old, word);
}
/**
* 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
*/
public boolean getWrapStyleWord() {
return word;
}
/**
* 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.
*/
public int getLineOfOffset(int offset) throws BadLocationException {
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);
}
}
/**
* Determines the number of lines contained in the area.
*
* @return the number of lines > 0
*/
public int getLineCount() {
Element map = getDocument().getDefaultRootElement();
return map.getElementCount();
}
/**
* 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).
*/
public int getLineStartOffset(int line) throws BadLocationException {
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();
}
}
/**
* 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).
*/
public int getLineEndOffset(int line) throws BadLocationException {
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);
}
}
// --- java.awt.TextArea methods ---------------------------------
/**
* Inserts the specified text at the specified position. Does nothing
* if the model is null or if the text is null or empty.
*
* @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
*/
public void insert(String str, int pos) {
Document doc = getDocument();
if (doc != null) {
try {
doc.insertString(pos, str, null);
} catch (BadLocationException e) {
throw new IllegalArgumentException(e.getMessage());
}
}
}
/**
* Appends the given text to the end of the document. Does nothing if
* the model is null or the string is null or empty.
*
* @param str the text to insert
* @see #insert
*/
public void append(String str) {
Document doc = getDocument();
if (doc != null) {
try {
doc.insertString(doc.getLength(), str, null);
} catch (BadLocationException e) {
}
}
}
/**
* 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.
*
* @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
*/
public void replaceRange(String str, int start, int end) {
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());
}
}
}
/**
* Returns the number of rows in the TextArea.
*
* @return the number of rows >= 0
*/
public int getRows() {
return 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
*/
public void setRows(int rows) {
int oldVal = this.rows;
if (rows < 0) {
throw new IllegalArgumentException("rows less than zero.");
}
if (rows != oldVal) {
this.rows = rows;
invalidate();
}
}
/**
* Defines the meaning of the height of a row. This defaults to
* the height of the font.
*
* @return the height >= 1
*/
protected int getRowHeight() {
if (rowHeight == 0) {
FontMetrics metrics = getFontMetrics(getFont());
rowHeight = metrics.getHeight();
}
return rowHeight;
}
/**
* Returns the number of columns in the TextArea.
*
* @return number of columns >= 0
*/
public int getColumns() {
return 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
*/
public void setColumns(int columns) {
int oldVal = this.columns;
if (columns < 0) {
throw new IllegalArgumentException("columns less than zero.");
}
if (columns != oldVal) {
this.columns = columns;
invalidate();
}
}
/**
* 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
*/
protected int getColumnWidth() {
if (columnWidth == 0) {
FontMetrics metrics = getFontMetrics(getFont());
columnWidth = metrics.charWidth('m');
}
return columnWidth;
}
// --- Component methods -----------------------------------------
/**
* 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
*/
public Dimension getPreferredSize() {
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;
}
/**
* 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
*/
public void setFont(Font f) {
super.setFont(f);
rowHeight = 0;
columnWidth = 0;
}
/**
* 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.
*/
protected String paramString() {
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;
}
// --- Scrollable methods ----------------------------------------
/**
* 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.
*/
public boolean getScrollableTracksViewportWidth() {
return (wrap) ? true : super.getScrollableTracksViewportWidth();
}
/**
* 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
*/
public Dimension getPreferredScrollableViewportSize() {
Dimension size = super.getPreferredScrollableViewportSize();
size = (size == null) ? new Dimension(400,400) : size;
Insets insets = getInsets();
size.width = (columns == 0) ? size.width :
columns * getColumnWidth() + insets.left + insets.right;
size.height = (rows == 0) ? size.height :
rows * getRowHeight() + insets.top + insets.bottom;
return size;
}
/**
* 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
*/
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
switch (orientation) {
case SwingConstants.VERTICAL:
return getRowHeight();
case SwingConstants.HORIZONTAL:
return getColumnWidth();
default:
throw new IllegalArgumentException("Invalid orientation: " + orientation);
}
}
/**
* See readObject() and writeObject() in JComponent for more
* information about serialization in Swing.
*/
private void writeObject(ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
if (getUIClassID().equals(uiClassID)) {
byte count = JComponent.getWriteObjCounter(this);
JComponent.setWriteObjCounter(this, --count);
if (count == 0 && ui != null) {
ui.installUI(this);
}
}
}
/////////////////
// Accessibility support
////////////////
/**
* 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
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleJTextArea();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* JTextArea class. It provides an implementation of the
* Java Accessibility API appropriate to text area user-interface
* elements.
*
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*/
protected class AccessibleJTextArea extends AccessibleJTextComponent {
/**
* Gets the state set of this object.
*
* @return an instance of AccessibleStateSet describing the states
* of the object
* @see AccessibleStateSet
*/
public AccessibleStateSet getAccessibleStateSet() {
AccessibleStateSet states = super.getAccessibleStateSet();
states.add(AccessibleState.MULTI_LINE);
return states;
}
}
// --- variables -------------------------------------------------
private int rows;
private int columns;
private int columnWidth;
private int rowHeight;
private boolean wrap;
private boolean word;
}