public class TextField extends TextComponent
TextField object is a text component
that allows for the editing of a single line of text.
For example, the following image depicts a frame with four
text fields of varying widths. Two of these text fields
display the predefined text "Hello".
Here is the code that produces these four text fields:
TextField tf1, tf2, tf3, tf4;
// a blank text field
tf1 = new TextField();
// blank field of 20 columns
tf2 = new TextField("", 20);
// predefined text displayed
tf3 = new TextField("Hello!");
// predefined text in 30 columns
tf4 = new TextField("Hello", 30);
Every time the user types a key in the text field, one or
more key events are sent to the text field. A KeyEvent
may be one of three types: keyPressed, keyReleased, or keyTyped.
The properties of a key event indicate which of these types
it is, as well as additional information about the event,
such as what modifiers are applied to the key event and the
time at which the event occurred.
The key event is passed to every KeyListener
or KeyAdapter object which registered to receive such
events using the component's addKeyListener method.
(KeyAdapter objects implement the
KeyListener interface.)
It is also possible to fire an ActionEvent.
If action events are enabled for the text field, they may
be fired by pressing the Return key.
The TextField class's processEvent
method examines the action event and passes it along to
processActionEvent. The latter method redirects the
event to any ActionListener objects that have
registered to receive action events generated by this
text field.
| Modifier and Type | Class and Description |
|---|---|
protected class |
TextField.AccessibleAWTTextField
This class implements accessibility support for the
TextField class. |
TextComponent.AccessibleAWTTextComponentComponent.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategytextListeneraccessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENTABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH| Constructor and Description |
|---|
TextField()
Constructs a new text field.
|
TextField(int columns)
Constructs a new empty text field with the specified number
of columns.
|
TextField(String text)
Constructs a new text field initialized with the specified text.
|
TextField(String text,
int columns)
Constructs a new text field initialized with the specified text
to be displayed, and wide enough to hold the specified
number of columns.
|
| Modifier and Type | Method and Description |
|---|---|
void |
addActionListener(ActionListener l)
Adds the specified action listener to receive
action events from this text field.
|
void |
addNotify()
Creates the TextField's peer.
|
boolean |
echoCharIsSet()
Indicates whether or not this text field has a
character set for echoing.
|
AccessibleContext |
getAccessibleContext()
Gets the AccessibleContext associated with this TextField.
|
ActionListener[] |
getActionListeners()
Returns an array of all the action listeners
registered on this textfield.
|
int |
getColumns()
Gets the number of columns in this text field.
|
char |
getEchoChar()
Gets the character that is to be used for echoing.
|
<T extends EventListener> |
getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered
as
FooListeners
upon this TextField. |
Dimension |
getMinimumSize()
Gets the minimum dimensions for this text field.
|
Dimension |
getMinimumSize(int columns)
Gets the minimum dimensions for a text field with
the specified number of columns.
|
Dimension |
getPreferredSize()
Gets the preferred size of this text field.
|
Dimension |
getPreferredSize(int columns)
Gets the preferred size of this text field
with the specified number of columns.
|
Dimension |
minimumSize()
Deprecated.
As of JDK version 1.1,
replaced by
getMinimumSize(). |
Dimension |
minimumSize(int columns)
Deprecated.
As of JDK version 1.1,
replaced by
getMinimumSize(int). |
protected String |
paramString()
Returns a string representing the state of this
TextField. |
Dimension |
preferredSize()
Deprecated.
As of JDK version 1.1,
replaced by
getPreferredSize(). |
Dimension |
preferredSize(int columns)
Deprecated.
As of JDK version 1.1,
replaced by
getPreferredSize(int). |
protected void |
processActionEvent(ActionEvent e)
Processes action events occurring on this text field by
dispatching them to any registered
ActionListener objects. |
protected void |
processEvent(AWTEvent e)
Processes events on this text field.
|
void |
removeActionListener(ActionListener l)
Removes the specified action listener so that it no longer
receives action events from this text field.
|
void |
setColumns(int columns)
Sets the number of columns in this text field.
|
void |
setEchoChar(char c)
Sets the echo character for this text field.
|
void |
setEchoCharacter(char c)
Deprecated.
As of JDK version 1.1,
replaced by
setEchoChar(char). |
void |
setText(String t)
Sets the text that is presented by this
text component to be the specified text.
|
addTextListener, enableInputMethods, getBackground, getCaretPosition, getInputMethodRequests, getSelectedText, getSelectionEnd, getSelectionStart, getText, getTextListeners, isEditable, processTextEvent, removeNotify, removeTextListener, select, selectAll, setBackground, setCaretPosition, setEditable, setSelectionEnd, setSelectionStartaction, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, prepareImage, prepareImage, print, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validatepublic TextField()
throws HeadlessException
HeadlessException - if GraphicsEnvironment.isHeadless()
returns true.GraphicsEnvironment.isHeadless()public TextField(String text) throws HeadlessException
text - the text to be displayed. If
text is null, the empty
string "" will be displayed.HeadlessException - if GraphicsEnvironment.isHeadless()
returns true.GraphicsEnvironment.isHeadless()public TextField(int columns)
throws HeadlessException
columns - the number of columns. If
columns is less than 0,
columns is set to 0.HeadlessException - if GraphicsEnvironment.isHeadless()
returns true.GraphicsEnvironment.isHeadless()public TextField(String text, int columns) throws HeadlessException
text - the text to be displayed. If
text is null, the empty
string "" will be displayed.columns - the number of columns. If
columns is less than 0,
columns is set to 0.HeadlessException - if GraphicsEnvironment.isHeadless()
returns true.GraphicsEnvironment.isHeadless()public void addNotify()
addNotify in class TextComponentTextComponent.removeNotify()public char getEchoChar()
An echo character is useful for text fields where
user input should not be echoed to the screen, as in
the case of a text field for entering a password.
If echoChar = 0, user
input is echoed to the screen unchanged.
A Java platform implementation may support only a limited, non-empty set of echo characters. This function returns the echo character originally requested via setEchoChar(). The echo character actually used by the TextField implementation might be different.
echoCharIsSet(),
setEchoChar(char)public void setEchoChar(char c)
An echo character is useful for text fields where
user input should not be echoed to the screen, as in
the case of a text field for entering a password.
Setting echoChar = 0 allows
user input to be echoed to the screen again.
A Java platform implementation may support only a limited, non-empty set of echo characters. Attempts to set an unsupported echo character will cause the default echo character to be used instead. Subsequent calls to getEchoChar() will return the echo character originally requested. This might or might not be identical to the echo character actually used by the TextField implementation.
c - the echo character for this text field.echoCharIsSet(),
getEchoChar()@Deprecated public void setEchoCharacter(char c)
setEchoChar(char).public void setText(String t)
setText in class TextComponentt - the new text.TextComponent.getText()public boolean echoCharIsSet()
An echo character is useful for text fields where user input should not be echoed to the screen, as in the case of a text field for entering a password.
true if this text field has
a character set for echoing;
false otherwise.setEchoChar(char),
getEchoChar()public int getColumns()
setColumns(int)public void setColumns(int columns)
columns - the number of columns.IllegalArgumentException - if the value
supplied for columns
is less than 0.getColumns()public Dimension getPreferredSize(int columns)
columns - the number of columns
in this text field.@Deprecated public Dimension preferredSize(int columns)
getPreferredSize(int).public Dimension getPreferredSize()
getPreferredSize in class ComponentComponent.getMinimumSize(),
LayoutManager@Deprecated public Dimension preferredSize()
getPreferredSize().preferredSize in class Componentpublic Dimension getMinimumSize(int columns)
columns - the number of columns in
this text field.@Deprecated public Dimension minimumSize(int columns)
getMinimumSize(int).public Dimension getMinimumSize()
getMinimumSize in class ComponentComponent.getPreferredSize(),
LayoutManager@Deprecated public Dimension minimumSize()
getMinimumSize().minimumSize in class Componentpublic void addActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l - the action listener.removeActionListener(java.awt.event.ActionListener),
getActionListeners(),
ActionListenerpublic void removeActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l - the action listener.addActionListener(java.awt.event.ActionListener),
getActionListeners(),
ActionListenerpublic ActionListener[] getActionListeners()
ActionListeners
or an empty array if no action
listeners are currently registeredaddActionListener(java.awt.event.ActionListener),
removeActionListener(java.awt.event.ActionListener),
ActionListenerpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListeners
upon this TextField.
FooListeners are registered using the
addFooListener method.
You can specify the listenerType argument
with a class literal, such as
FooListener.class.
For example, you can query a
TextField t
for its action listeners with the following code:
ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class));If no such listeners exist, this method returns an empty array.
getListeners in class TextComponentlistenerType - the type of listeners requested; this parameter
should specify an interface that descends from
java.util.EventListenerFooListeners on this textfield,
or an empty array if no such
listeners have been addedClassCastException - if listenerType
doesn't specify a class or interface that implements
java.util.EventListenergetActionListeners()protected void processEvent(AWTEvent e)
ActionEvent,
it invokes the processActionEvent
method. Otherwise, it invokes processEvent
on the superclass.
Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.
processEvent in class TextComponente - the eventActionEvent,
processActionEvent(java.awt.event.ActionEvent)protected void processActionEvent(ActionEvent e)
ActionListener objects.
This method is not called unless action events are enabled for this component. Action events are enabled when one of the following occurs:
ActionListener object is registered
via addActionListener.
enableEvents.
Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.
e - the action eventActionListener,
addActionListener(java.awt.event.ActionListener),
Component.enableEvents(long)protected String paramString()
TextField.
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.paramString in class TextComponentpublic AccessibleContext getAccessibleContext()
getAccessibleContext in interface AccessiblegetAccessibleContext in class TextComponent Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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