java.lang.Object | |||||
↳ | java.awt.Component | ||||
↳ | java.awt.Container | ||||
↳ | javax.swing.JComponent | ||||
↳ | javax.swing.text.JTextComponent | ||||
↳ | javax.swing.JTextField |
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JTextField
is a lightweight component that allows the editing
of a single line of text.
For information on and examples of using text fields,
see
How to Use Text Fields
in The Java Tutorial.
JTextField
is intended to be source-compatible
with java.awt.TextField
where it is reasonable to do so. This
component has capabilities not found in the java.awt.TextField
class. The superclass should be consulted for additional capabilities.
JTextField
has a method to establish the string used as the
command string for the action event that gets fired. The
java.awt.TextField
used the text of the field as the command
string for the ActionEvent
.
JTextField
will use the command
string set with the setActionCommand
method if not null
,
otherwise it will use the text of the field as a compatibility with
java.awt.TextField
.
The method setEchoChar
and getEchoChar
are not provided directly to avoid a new implementation of a
pluggable look-and-feel inadvertently exposing password characters.
To provide password-like services a separate class JPasswordField
extends JTextField
to provide this service with an independently
pluggable look-and-feel.
The java.awt.TextField
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 = ??;
JTextField myArea = ??;
myArea.getDocument().addDocumentListener(myListener);
The horizontal alignment of JTextField
can be set to be left
justified, leading justified, centered, right justified or trailing justified.
Right/trailing justification is useful if the required size
of the field text is smaller than the size allocated to it.
This is determined by the setHorizontalAlignment
and getHorizontalAlignment
methods. The default
is to be leading justified.
How the text field consumes VK_ENTER events depends on whether the text field has any action listeners. If so, then VK_ENTER results in the listeners getting an ActionEvent, and the VK_ENTER event is consumed. This is compatible with how AWT text fields handle VK_ENTER events. If the text field has no action listeners, then as of v 1.3 the VK_ENTER event is not consumed. Instead, the bindings of ancestor components are processed, which enables the default button feature of JFC/Swing to work.
Customized fields can easily be created by extending the model and changing the default model provided. For example, the following piece of code will create a field that holds only upper case characters. It will work even if text is pasted into from the clipboard or it is altered via programmatic changes.
public class UpperCaseField extends JTextField {
public UpperCaseField(int cols) {
super(cols);
}
protected Document createDefaultModel() {
return new UpperCaseDocument();
}
static class UpperCaseDocument extends PlainDocument {
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException {
if (str == null) {
return;
}
char[] upper = str.toCharArray();
for (int i = 0; i < upper.length; i++) {
upper[i] = Character.toUpperCase(upper[i]);
}
super.insertString(offs, new String(upper), a);
}
}
}
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 XMLEncoder
.
Nested Classes | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
JTextField.AccessibleJTextField | This class implements accessibility support for the
JTextField class. |
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
String | notifyAction | Name of the action to send notification that the contents of the field have been accepted. |
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Inherited Constants | |||||||||||
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Inherited Fields | |||||||||||
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Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Constructs a new
TextField . | |||||||||||
Constructs a new
TextField initialized with the
specified text. | |||||||||||
Constructs a new empty
TextField with the specified
number of columns. | |||||||||||
Constructs a new
TextField initialized with the
specified text and columns. | |||||||||||
Constructs a new
JTextField that uses the given text
storage model and the given number of columns. |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Adds the specified action listener to receive
action events from this textfield.
| |||||||||||
Gets the
AccessibleContext associated with this
JTextField . | |||||||||||
Returns the currently set
Action for this
ActionEvent source, or null
if no Action is set. | |||||||||||
Returns an array of all the
ActionListener s added
to this JTextField with addActionListener(). | |||||||||||
Fetches the command list for the editor.
| |||||||||||
Returns the number of columns in this
TextField . | |||||||||||
Returns the horizontal alignment of the text.
| |||||||||||
Gets the visibility of the text field.
| |||||||||||
Returns the preferred size
Dimensions needed for this
TextField . | |||||||||||
Gets the scroll offset, in pixels.
| |||||||||||
Gets the class ID for a UI.
| |||||||||||
Calls to
revalidate that come from within the
textfield itself will
be handled by validating the textfield, unless the textfield
is contained within a JViewport ,
in which case this returns false. | |||||||||||
Processes action events occurring on this textfield by
dispatching them to any registered
ActionListener objects. | |||||||||||
Removes the specified action listener so that it no longer
receives action events from this textfield.
| |||||||||||
Scrolls the field left or right.
| |||||||||||
Sets the
Action for the ActionEvent source. | |||||||||||
Sets the command string used for action events.
| |||||||||||
Sets the number of columns in this
TextField ,
and then invalidate the layout. | |||||||||||
Associates the editor with a text document.
| |||||||||||
Sets the current font.
| |||||||||||
Sets the horizontal alignment of the text.
| |||||||||||
Sets the scroll offset, in pixels.
|
Protected Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Updates the textfield's state in response to property changes in
associated action.
| |||||||||||
Sets the properties on this textfield to match those in the specified
Action . | |||||||||||
Creates and returns a
PropertyChangeListener that is
responsible for listening for changes from the specified
Action and updating the appropriate properties. | |||||||||||
Creates the default implementation of the model
to be used at construction if one isn't explicitly
given.
| |||||||||||
Notifies all listeners that have registered interest for
notification on this event type.
| |||||||||||
Returns the column width.
| |||||||||||
Returns a string representation of this
JTextField . |
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Inherited Methods | |||||||||||
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Name of the action to send notification that the contents of the field have been accepted. Typically this is bound to a carriage-return.
Constructs a new TextField
. A default model is created,
the initial string is null
,
and the number of columns is set to 0.
Constructs a new TextField
initialized with the
specified text. A default model is created and the number of
columns is 0.
text | the text to be displayed, or null
|
---|
Constructs a new empty TextField
with the specified
number of columns.
A default model is created and the initial string is set to
null
.
columns | the number of columns to use to calculate the preferred width; if columns is set to zero, the preferred width will be whatever naturally results from the component implementation |
---|
Constructs a new TextField
initialized with the
specified text and columns. A default model is created.
text | the text to be displayed, or null |
---|---|
columns | the number of columns to use to calculate the preferred width; if columns is set to zero, the preferred width will be whatever naturally results from the component implementation |
Constructs a new JTextField
that uses the given text
storage model and the given number of columns.
This is the constructor through which the other constructors feed.
If the document is null
, a default model is created.
doc | the text storage to use; if this is null ,
a default will be provided by calling the
createDefaultModel method |
---|---|
text | the initial string to display, or null |
columns | the number of columns to use to calculate
the preferred width >= 0; if columns
is set to zero, the preferred width will be whatever
naturally results from the component implementation |
IllegalArgumentException | if columns < 0
|
---|
Adds the specified action listener to receive action events from this textfield.
l | the action listener to be added |
---|
Gets the AccessibleContext
associated with this
JTextField
. For JTextFields
,
the AccessibleContext
takes the form of an
AccessibleJTextField
.
A new AccessibleJTextField
instance is created
if necessary.
AccessibleJTextField
that serves as the
AccessibleContext
of this JTextField
Returns the currently set Action
for this
ActionEvent
source, or null
if no Action
is set.
Action
for this ActionEvent
source,
or null
Returns an array of all the ActionListener
s added
to this JTextField with addActionListener().
ActionListener
s added or an empty
array if no listeners have been addedFetches the command list for the editor. This is the list of commands supported by the plugged-in UI augmented by the collection of commands that the editor itself supports. These are useful for binding to events, such as in a keymap.
Returns the number of columns in this TextField
.
Returns the horizontal alignment of the text. Valid keys are:
JTextField.LEFT
JTextField.CENTER
JTextField.RIGHT
JTextField.LEADING
JTextField.TRAILING
Gets the visibility of the text field. This can be adjusted to change the location of the visible area if the size of the field is greater than the area that was allocated to the field.
The fields look-and-feel implementation manages
the values of the minimum, maximum, and extent
properties on the BoundedRangeModel
.
Returns the preferred size Dimensions
needed for this
TextField
. If a non-zero number of columns has been
set, the width is set to the columns multiplied by
the column width.
Gets the scroll offset, in pixels.
Calls to revalidate
that come from within the
textfield itself will
be handled by validating the textfield, unless the textfield
is contained within a JViewport
,
in which case this returns false.
JViewPort
return false, otherwise return trueProcesses action events occurring on this textfield by
dispatching them to any registered ActionListener
objects.
This is normally called by the controller registered with
textfield.
Removes the specified action listener so that it no longer receives action events from this textfield.
l | the action listener to be removed |
---|
Scrolls the field left or right.
r | the region to scroll |
---|
Sets the Action
for the ActionEvent
source.
The new Action
replaces
any previously set Action
but does not affect
ActionListeners
independently
added with addActionListener
.
If the Action
is already a registered
ActionListener
for the ActionEvent
source, it is not re-registered.
Setting the Action
results in immediately changing
all the properties described in
Swing Components Supporting Action
.
Subsequently, the textfield's properties are automatically updated
as the Action
's properties change.
This method uses three other methods to set
and help track the Action
's property values.
It uses the configurePropertiesFromAction
method
to immediately change the textfield's properties.
To track changes in the Action
's property values,
this method registers the PropertyChangeListener
returned by createActionPropertyChangeListener
. The
default PropertyChangeListener
invokes the
actionPropertyChanged
method when a property in the
Action
changes.
a | the Action for the JTextField ,
or null |
---|
Sets the command string used for action events.
command | the command string |
---|
Sets the number of columns in this TextField
,
and then invalidate the layout.
columns | the number of columns >= 0 |
---|
IllegalArgumentException | if columns
is less than 0 |
---|
Associates the editor with a text document. The currently registered factory is used to build a view for the document, which gets displayed by the editor after revalidation. A PropertyChange event ("document") is propagated to each listener.
doc | the document to display/edit |
---|
Sets the current font. This removes cached row height and column
width so the new font will be reflected.
revalidate
is called after setting the font.
f | the new font |
---|
Sets the horizontal alignment of the text. Valid keys are:
JTextField.LEFT
JTextField.CENTER
JTextField.RIGHT
JTextField.LEADING
JTextField.TRAILING
invalidate
and repaint
are called when the
alignment is set,
and a PropertyChange
event ("horizontalAlignment") is fired.alignment | the alignment |
---|
IllegalArgumentException | if alignment
is not a valid key |
---|
Sets the scroll offset, in pixels.
scrollOffset | the offset >= 0 |
---|
Updates the textfield's state in response to property changes in
associated action. This method is invoked from the
PropertyChangeListener
returned from
createActionPropertyChangeListener
. Subclasses do not normally
need to invoke this. Subclasses that support additional Action
properties should override this and
configurePropertiesFromAction
.
Refer to the table at
Swing Components Supporting Action
for a list of
the properties this method sets.
action | the Action associated with this textfield |
---|---|
propertyName | the name of the property that changed |
Sets the properties on this textfield to match those in the specified
Action
. Refer to
Swing Components Supporting Action
for more
details as to which properties this sets.
a | the Action from which to get the properties,
or null |
---|
Creates and returns a PropertyChangeListener
that is
responsible for listening for changes from the specified
Action
and updating the appropriate properties.
Warning: If you subclass this do not create an anonymous
inner class. If you do the lifetime of the textfield will be tied to
that of the Action
.
a | the textfield's action |
---|
Creates the default implementation of the model
to be used at construction if one isn't explicitly
given. An instance of PlainDocument
is returned.
Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created. The listener list is processed in last to first order.
Returns the 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 a string representation of this JTextField
.
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
.
JTextField