|
JavaTM 2 Platform Std. Ed. v1.3 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
java.lang.Object
|
+--java.awt.Component
|
+--java.awt.TextComponent
|
+--java.awt.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| Inner Class Summary | |
protected class |
TextField.AccessibleAWTTextField
This class implements accessibility support for the TextField class. |
| Inner classes inherited from class java.awt.TextComponent |
TextComponent.AccessibleAWTTextComponent |
| Inner classes inherited from class java.awt.Component |
Component.AccessibleAWTComponent |
| 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. |
|
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. |
int |
getColumns()
Gets the number of columns in this text field. |
char |
getEchoChar()
Gets the character that is to be used for echoing. |
EventListener[] |
getListeners(Class listenerType)
Return an array of all the listeners that were added to the TextField with addXXXListener(), where XXX is the name of the listenerType
argument. |
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. |
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 the parameter string representing the state of this text field. |
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. |
| Methods inherited from class java.awt.TextComponent |
addTextListener, getBackground, getCaretPosition, getSelectedText, getSelectionEnd, getSelectionStart, getText, 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()
public TextField(String text)
text - the text to be displayed. If
text is null, the empty
string "" will be displayed.public TextField(int columns)
columns - the number of columns. If
columns is less than 0,
columns is set to 0.
public TextField(String text,
int columns)
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.| Method Detail |
public void addNotify()
addNotify in class Componentjava.awt.ComponentComponent.isDisplayable(),
Component.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()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.public Dimension preferredSize(int columns)
getPreferredSize(int).
public Dimension getPreferredSize()
getPreferredSize in class Componentpublic Dimension preferredSize()
getPreferredSize().
preferredSize in class Componentpublic Dimension getMinimumSize(int columns)
columns - the number of columns in
this text field.public Dimension minimumSize(int columns)
getMinimumSize(int).
public Dimension getMinimumSize()
getMinimumSize in class Componentpublic Dimension minimumSize()
getMinimumSize().
minimumSize in class Componentpublic void addActionListener(ActionListener l)
l - the action listener.removeActionListener(java.awt.event.ActionListener)public void removeActionListener(ActionListener l)
l - the action listener.addActionListener(java.awt.event.ActionListener)public EventListener[] getListeners(Class listenerType)
listenerType
argument. For example, to get all of the ActionListener(s) for the
given TextField t, one would write:
ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class))If no such listener list exists, then an empty array is returned.
getListeners in class TextComponentlistenerType - Type of listeners requestedprotected void processEvent(AWTEvent e)
ActionEvent,
it invokes the processActionEvent
method. Otherwise, it invokes processEvent
on the superclass.processEvent in class TextComponente - the event.ActionEvent,
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.
e - the action event.ActionListener,
addActionListener(java.awt.event.ActionListener),
Component.enableEvents(long)protected String paramString()
paramString in class TextComponentpublic AccessibleContext getAccessibleContext()
getAccessibleContext in class TextComponent
|
JavaTM 2 Platform Std. Ed. v1.3 |
|||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
Java, Java 2D, and JDBC are trademarks or registered trademarks of Sun Microsystems, Inc. in the US and other countries.
Copyright 1993-2000 Sun Microsystems, Inc. 901 San Antonio Road
Palo Alto, California, 94303, U.S.A. All Rights Reserved.