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JavaTM 2 Platform Standard Ed. 5.0 |
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java.lang.Objectjava.awt.Component
java.awt.TextComponent
java.awt.TextField
public class TextField
A 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.
KeyEvent,
KeyAdapter,
KeyListener,
ActionEvent,
Component.addKeyListener(java.awt.event.KeyListener),
processEvent(java.awt.AWTEvent),
processActionEvent(java.awt.event.ActionEvent),
addActionListener(java.awt.event.ActionListener),
Serialized Form| Nested Class Summary | |
|---|---|
protected class |
TextField.AccessibleAWTTextField
This class implements accessibility support for the TextField class. |
| Nested classes/interfaces inherited from class java.awt.TextComponent |
|---|
TextComponent.AccessibleAWTTextComponent |
| Nested classes/interfaces inherited from class java.awt.Component |
|---|
Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy |
| Field Summary |
|---|
| Fields inherited from class java.awt.TextComponent |
|---|
textListener |
| Fields inherited from class java.awt.Component |
|---|
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT |
| Fields inherited from interface java.awt.image.ImageObserver |
|---|
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH |
| Constructor Summary | |
|---|---|
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. |
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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. |
|
| Method Summary | ||
|---|---|---|
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. |
|
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getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered as FooListeners
upon this TextField. |
|
Dimension |
getMinimumSize()
Gets the minumum dimensions for this text field. |
|
Dimension |
getMinimumSize(int columns)
Gets the minumum dimensions for a text field with the specified number of columns. |
|
Dimension |
getPreferredSize()
Gets the preferred size of this text field. |
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Dimension |
getPreferredSize(int columns)
Gets the preferred size of this text field with the specified number of columns. |
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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). |
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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. |
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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. |
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void |
setEchoCharacter(char c)
Deprecated. As of JDK version 1.1, replaced by setEchoChar(char). |
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void |
setText(String t)
Sets the text that is presented by this text component to be the specified text. |
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| Methods inherited from class java.awt.TextComponent |
|---|
addTextListener, enableInputMethods, getBackground, getCaretPosition, getInputMethodRequests, getSelectedText, getSelectionEnd, getSelectionStart, getText, getTextListeners, isEditable, processTextEvent, removeNotify, removeTextListener, select, selectAll, setBackground, setCaretPosition, setEditable, setSelectionEnd, setSelectionStart |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
|---|
public 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()| Method Detail |
|---|
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.
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.
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)
l - the action listener.removeActionListener(java.awt.event.ActionListener),
getActionListeners(),
ActionListenerpublic void removeActionListener(ActionListener l)
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),
java.awt.eventpublic <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.EventListener
FooListeners on this textfield,
or an empty array if no such
listeners have been added
ClassCastException - 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
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JavaTM 2 Platform Standard Ed. 5.0 |
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Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.