Class TextField
- java.lang.Object
-
- java.awt.Component
-
- java.awt.TextComponent
-
- java.awt.TextField
- All Implemented Interfaces:
-
ImageObserver
,MenuContainer
,Serializable
,Accessible
public class TextField extends TextComponent
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.
- Since:
- 1.0
- See Also:
-
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
Modifier and Type | Class | Description |
---|---|---|
protected class | TextField.AccessibleAWTTextField | This class implements accessibility support for the |
Nested classes/interfaces declared in class java.awt.TextComponent
TextComponent.AccessibleAWTTextComponent
Nested classes/interfaces declared in class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
Field Summary
Fields declared in class java.awt.TextComponent
textListener
Fields declared in class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
Fields declared in interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor Summary
Constructor | 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. |
Method Summary
Modifier and Type | Method | 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 |
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 |
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 |
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 declared in class java.awt.TextComponent
addTextListener, enableInputMethods, getBackground, getCaretPosition, getSelectedText, getSelectionEnd, getSelectionStart, getText, getTextListeners, isEditable, processTextEvent, removeNotify, removeTextListener, select, selectAll, setBackground, setCaretPosition, setEditable, setSelectionEnd, setSelectionStart
Methods declared in class java.awt.Component
action, 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, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, 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, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setMixingCutoutShape, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Constructor Detail
TextField
public TextField() throws HeadlessException
Constructs a new text field.
- Throws:
-
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true. - See Also:
GraphicsEnvironment.isHeadless()
TextField
public TextField(String text) throws HeadlessException
Constructs a new text field initialized with the specified text.
- Parameters:
-
text
- the text to be displayed. Iftext
isnull
, the empty string""
will be displayed. Iftext
contains EOL and/or LF characters, then each will be replaced by space character. - Throws:
-
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true. - See Also:
GraphicsEnvironment.isHeadless()
TextField
public TextField(int columns) throws HeadlessException
Constructs a new empty text field with the specified number of columns. A column is an approximate average character width that is platform-dependent.
- Parameters:
-
columns
- the number of columns. Ifcolumns
is less than0
,columns
is set to0
. - Throws:
-
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true. - See Also:
GraphicsEnvironment.isHeadless()
TextField
public TextField(String text, int columns) throws HeadlessException
Constructs a new text field initialized with the specified text to be displayed, and wide enough to hold the specified number of columns. A column is an approximate average character width that is platform-dependent.
- Parameters:
-
text
- the text to be displayed. Iftext
isnull
, the empty string""
will be displayed. Iftext
contains EOL and/or LF characters, then each will be replaced by space character. -
columns
- the number of columns. Ifcolumns
is less than0
,columns
is set to0
. - Throws:
-
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true. - See Also:
GraphicsEnvironment.isHeadless()
Method Detail
addNotify
public void addNotify()
Creates the TextField's peer. The peer allows us to modify the appearance of the TextField without changing its functionality.
- Overrides:
-
addNotify
in classTextComponent
- See Also:
TextComponent.removeNotify()
getEchoChar
public char getEchoChar()
Gets the character that is to be used for echoing.
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.
- Returns:
- the echo character for this text field.
- See Also:
-
echoCharIsSet()
,setEchoChar(char)
setEchoChar
public void setEchoChar(char c)
Sets the echo character for this text field.
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.
- Parameters:
-
c
- the echo character for this text field. - Since:
- 1.1
- See Also:
-
echoCharIsSet()
,getEchoChar()
setEchoCharacter
@Deprecated public void setEchoCharacter(char c)
setEchoChar(char)
.Sets the character to be echoed when protected input is displayed.
- Parameters:
-
c
- the echo character for this text field
setText
public void setText(String t)
Sets the text that is presented by this text component to be the specified text.
- Overrides:
-
setText
in classTextComponent
- Parameters:
-
t
- the new text. Ift
isnull
, the empty string""
will be displayed. Ift
contains EOL and/or LF characters, then each will be replaced by space character. - See Also:
TextComponent.getText()
echoCharIsSet
public boolean echoCharIsSet()
Indicates whether or not this text field has a character set for echoing.
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.
- Returns:
-
true
if this text field has a character set for echoing;false
otherwise. - See Also:
-
setEchoChar(char)
,getEchoChar()
getColumns
public int getColumns()
Gets the number of columns in this text field. A column is an approximate average character width that is platform-dependent.
- Returns:
- the number of columns.
- Since:
- 1.1
- See Also:
setColumns(int)
setColumns
public void setColumns(int columns)
Sets the number of columns in this text field. A column is an approximate average character width that is platform-dependent.
- Parameters:
-
columns
- the number of columns. - Throws:
-
IllegalArgumentException
- if the value supplied forcolumns
is less than0
. - Since:
- 1.1
- See Also:
getColumns()
getPreferredSize
public Dimension getPreferredSize(int columns)
Gets the preferred size of this text field with the specified number of columns.
- Parameters:
-
columns
- the number of columns in this text field. - Returns:
- the preferred dimensions for displaying this text field.
- Since:
- 1.1
preferredSize
@Deprecated public Dimension preferredSize(int columns)
getPreferredSize(int)
.Returns the preferred size for this text field with the specified number of columns.
- Parameters:
-
columns
- the number of columns - Returns:
- the preferred size for the text field
getPreferredSize
public Dimension getPreferredSize()
Gets the preferred size of this text field.
- Overrides:
-
getPreferredSize
in classComponent
- Returns:
- the preferred dimensions for displaying this text field.
- Since:
- 1.1
- See Also:
-
Component.getMinimumSize()
,LayoutManager
preferredSize
@Deprecated public Dimension preferredSize()
getPreferredSize()
.Description copied from class: Component
Returns the component's preferred size.
- Overrides:
-
preferredSize
in classComponent
- Returns:
- the component's preferred size
getMinimumSize
public Dimension getMinimumSize(int columns)
Gets the minimum dimensions for a text field with the specified number of columns.
- Parameters:
-
columns
- the number of columns in this text field. - Returns:
- the minimum size for this text field
- Since:
- 1.1
minimumSize
@Deprecated public Dimension minimumSize(int columns)
getMinimumSize(int)
.Returns the minimum dimensions for a text field with the specified number of columns.
- Parameters:
-
columns
- the number of columns - Returns:
- the minimum size for this text field
getMinimumSize
public Dimension getMinimumSize()
Gets the minimum dimensions for this text field.
- Overrides:
-
getMinimumSize
in classComponent
- Returns:
- the minimum dimensions for displaying this text field.
- Since:
- 1.1
- See Also:
-
Component.getPreferredSize()
,LayoutManager
minimumSize
@Deprecated public Dimension minimumSize()
getMinimumSize()
.Description copied from class: Component
Returns the minimum size of this component.
- Overrides:
-
minimumSize
in classComponent
- Returns:
- the minimum size of this component
addActionListener
public void addActionListener(ActionListener l)
Adds the specified action listener to receive action events from this text field. If l is null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
- Parameters:
-
l
- the action listener. - Since:
- 1.1
- See Also:
-
removeActionListener(java.awt.event.ActionListener)
,getActionListeners()
,ActionListener
removeActionListener
public void removeActionListener(ActionListener l)
Removes the specified action listener so that it no longer receives action events from this text field. If l is null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
- Parameters:
-
l
- the action listener. - Since:
- 1.1
- See Also:
-
addActionListener(java.awt.event.ActionListener)
,getActionListeners()
,ActionListener
getActionListeners
public ActionListener[] getActionListeners()
Returns an array of all the action listeners registered on this textfield.
- Returns:
- all of this textfield's
ActionListener
s or an empty array if no action listeners are currently registered - Since:
- 1.4
- See Also:
-
addActionListener(java.awt.event.ActionListener)
,removeActionListener(java.awt.event.ActionListener)
,ActionListener
getListeners
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered as FooListener
s upon this TextField
. FooListener
s 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.
- Overrides:
-
getListeners
in classTextComponent
- Type Parameters:
-
T
- the type of the listeners - Parameters:
-
listenerType
- the type of listeners requested; this parameter should specify an interface that descends fromjava.util.EventListener
- Returns:
- an array of all objects registered as
FooListener
s on this textfield, or an empty array if no such listeners have been added - Throws:
-
ClassCastException
- iflistenerType
doesn't specify a class or interface that implementsjava.util.EventListener
- Since:
- 1.3
- See Also:
getActionListeners()
processEvent
protected void processEvent(AWTEvent e)
Processes events on this text field. If the event is an instance of 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.
- Overrides:
-
processEvent
in classTextComponent
- Parameters:
-
e
- the event - Since:
- 1.1
- See Also:
-
ActionEvent
,processActionEvent(java.awt.event.ActionEvent)
processActionEvent
protected void processActionEvent(ActionEvent e)
Processes action events occurring on this text field by dispatching them to any registered 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:
- An
ActionListener
object is registered viaaddActionListener
. - Action events are enabled via
enableEvents
.
Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
- Parameters:
-
e
- the action event - Since:
- 1.1
- See Also:
-
ActionListener
,addActionListener(java.awt.event.ActionListener)
,Component.enableEvents(long)
paramString
protected String paramString()
Returns a string representing the state of this 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
.
- Overrides:
-
paramString
in classTextComponent
- Returns:
- the parameter string of this text field
getAccessibleContext
public AccessibleContext getAccessibleContext()
Gets the AccessibleContext associated with this TextField. For text fields, the AccessibleContext takes the form of an AccessibleAWTTextField. A new AccessibleAWTTextField instance is created if necessary.
- Specified by:
-
getAccessibleContext
in interfaceAccessible
- Overrides:
-
getAccessibleContext
in classTextComponent
- Returns:
- an AccessibleAWTTextField that serves as the AccessibleContext of this TextField
- Since:
- 1.3