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Class com.sun.java.swing.JTextArea

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container
                   |
                   +----com.sun.java.swing.JComponent
                           |
                           +----com.sun.java.swing.text.JTextComponent
                                   |
                                   +----com.sun.java.swing.JTextArea

public class JTextArea

extends JTextComponent

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.

The java.awt.TextArea could be monitored for changes by adding a TextListener for TextEvent's. 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: 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 Swing1.0 applications. It will not be possible to load serialized Swing1.0 objects with future releases of Swing. The JDK1.2 release of Swing will be the compatibility baseline for the serialized form of Swing objects.

See Also:

JTextPane, JEditorPane

JTextArea()

Constructs a new TextArea.

JTextArea(Document)

Constructs a new JTextArea with the given document model, and defaults for all of the other arguments.

JTextArea(Document, String, int, int)

Constructs a new JTextArea with the specified number of rows and columns, and the given model.

JTextArea(int, int)

Constructs a new empty TextArea with the specified number of rows and columns.

JTextArea(String)

Constructs a new TextArea with the specified text displayed.

JTextArea(String, int, int)

Constructs a new TextArea with the specified text and number of rows and columns.

append(String)

Appends the given text to the end of the document.

createDefaultModel()

Creates the default implementation of the model to be used at construction if one isn't explicitly given.

getAccessibleContext()

Get the AccessibleContext associated with this JTextArea

getColumns()

Returns the number of columns in the TextArea.

getColumnWidth()

Gets column width.

getLineCount()

Determine the number of lines contained.

getLineEndOffset(int)

Determine the offset of the end of the given line.

getLineOfOffset(int)

Translate an offset into the components text to a line number.

getLineStartOffset(int)

Determine the offset of the start of the given line.

getLineWrap()

Get the line-wrapping policy of the text area.

getMinimumSize()

Returns the minimum size Dimensions of the TextArea.

getPreferredScrollableViewportSize()

Returns the preferred size of the viewport if this component is embedded in a JScrollPane.

getRowHeight()

Defines the meaning of the height of a row.

getRows()

Returns the number of rows in the TextArea.

getScrollableTracksViewportWidth()

Returns true if a viewport should always force the width of this Scrollable to match the width of the viewport.

getScrollableUnitIncrement(Rectangle, int, int)

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.

getTabSize()

Gets the number of characters used to expand tabs.

getUIClassID()

Returns the class ID for the UI.

insert(String, int)

Inserts the specified text at the specified position.

isManagingFocus()

Turns off tab traversal once focus gained.

paramString()

Returns the String of parameters for this TextArea.

replaceRange(String, int, int)

Replaces text from the indicated start to end position with the new text specified.

setColumns(int)

Sets the number of columns for this TextArea.

setFont(Font)

Sets the current font.

setLineWrap(boolean)

Set the line-wrapping policy of the text area.

setRows(int)

Sets the number of rows for this TextArea.

setTabSize(int)

Sets the number of characters to expand tabs to.

 public JTextArea()

Constructs a new TextArea.

 public JTextArea(String text)

Constructs a new TextArea with the specified text displayed.

Parameters:

text - the text to be displayed

 public JTextArea(int rows,
                  int columns)

Constructs a new empty TextArea with the specified number of rows and columns.

Parameters:

rows - the number of rows

columns - the number of columns

 public JTextArea(String text,
                  int rows,
                  int columns)

Constructs a new TextArea with the specified text and number of rows and columns.

Parameters:

text - the text to be displayed

rows - the number of rows

columns - the number of columns

 public JTextArea(Document doc)

Constructs a new JTextArea with the given document model, and defaults for all of the other arguments.

Parameters:

doc - the model to use

 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.

Parameters:

doc - the model to use

text - the text to be displayed

rows - the number of rows

columns - the number of columns

 public String getUIClassID()

Returns the class ID for the UI.

Returns:

the ID

Overrides:

getUIClassID in class JComponent

See Also:

getUIClassID, getUI

 protected Document createDefaultModel()

Creates the default implementation of the model to be used at construction if one isn't explicitly given.

Returns:

the default document model

 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.

Parameters:

size - number of characters to expand to

See Also:

getTabSize

 public int getTabSize()

Gets the number of characters used to expand tabs.

Returns:

the number of characters

 public void setLineWrap(boolean wrap)

Set 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.

Parameters:

wrap - indicates if lines should be wrapped.

See Also:

getLineWrap

 public boolean getLineWrap()

Get 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.

Returns:

s if lines will be wrapped.

 public int getLineOfOffset(int offset) throws BadLocationException

Translate an offset into the components text to a line number.

Throws: BadLocationException

Thrown if the offset is less than zero or greater than the document length.

 public int getLineCount()

Determine the number of lines contained.

 public int getLineStartOffset(int line) throws BadLocationException

Determine the offset of the start of the given line.

Parameters:

line - The line number to translate. Lines are numbered from 0.

Throws: 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

Determine the offset of the end of the given line.

Parameters:

line - The line number to translate. Lines are numbered from 0.

Throws: 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 void insert(String str,
                    int pos)

Inserts the specified text at the specified position.

This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information.

Parameters:

str - the text to insert

pos - the position at which to insert

Throws: IllegalArgumentException

if pos is an invalid position in the model

See Also:

setText, replaceRange

 public void append(String str)

Appends the given text to the end of the document.

This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information.

Parameters:

str - the text to insert

See Also:

insert

 public void replaceRange(String str,
                          int start,
                          int end)

Replaces text from the indicated start to end position with the new text specified.

This method is thread safe, although most Swing methods are not. Please see Threads and Swing for more information.

Parameters:

str - the text to use as the replacement

start - the start position

end - the end position

Throws: IllegalArgumentException

if part of the range is an invalid position in the model

See Also:

insert, replaceRange

 public boolean isManagingFocus()

Turns off tab traversal once focus gained.

Returns:

true, to indicate that the focus is being managed

Overrides:

isManagingFocus in class JComponent

 public int getRows()

Returns the number of rows in the TextArea.

Returns:

the number of rows

 public void setRows(int rows)

Sets the number of rows for this TextArea.

Parameters:

rows - the number of rows

Throws: IllegalArgumentException

if rows is less than 0

See Also:

getRows

 protected int getRowHeight()

Defines the meaning of the height of a row. This defaults to the height of the font.

Returns:

the height

 public int getColumns()

Returns the number of columns in the TextArea.

Returns:

number of columns

 public void setColumns(int columns)

Sets the number of columns for this TextArea.

Parameters:

columns - the number of columns

Throws: IllegalArgumentException

if columns is less than 0

See Also:

getColumns

 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.

Returns:

the column width

 public Dimension getMinimumSize()

Returns the minimum size Dimensions of the TextArea. By default this is set to the preferred size.

Returns:

the dimensions

Overrides:

getMinimumSize in class JComponent

 public void setFont(Font f)

Sets the current font. This removes cached row height and column width so the new font will be reflected.

Parameters:

f - the font to use as the current font

Overrides:

setFont in class Component

 protected String paramString()

Returns the String of parameters for this TextArea.

Returns:

the string of parameters

Overrides:

paramString in class Container

 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.

Returns:

True if a viewport should force the Scrollables width to match its own.

Overrides:

getScrollableTracksViewportWidth in class JTextComponent

 public 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.

Returns:

The preferredSize of a JViewport whose view is this Scrollable.

Overrides:

getPreferredScrollableViewportSize in class JTextComponent

See Also:

getPreferredSize

 public int getScrollableUnitIncrement(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 vaules returned by the getRowHeight and getColumnWidth methods.

Scrolling containers, like JScrollPane, will use this method each time the user requests a unit scroll.

Parameters:

visibleRect - The view area visible within the viewport

orientation - Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.

direction - Less than zero to scroll up/left, greater than zero for down/right.

Returns:

The "unit" increment for scrolling in the specified direction

Overrides:

getScrollableUnitIncrement in class JTextComponent

See Also:

setUnitIncrement, getRowHeight, getColumnWidth

 public AccessibleContext getAccessibleContext()

Get the AccessibleContext associated with this JTextArea

Returns:

the AccessibleContext of this JTextArea

Overrides:

getAccessibleContext in class JTextComponent

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