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Class java.awt.TextField

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.TextComponent
              |
              +--java.awt.TextField

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, AWT sends two action events to the text field. The first one represents the key press and the second one, the key release. Each action event embodies the state of the system at the time that some action occurred. The properties of an action event indicate which key was pressed, what modifier keys were also pressed, and the time at which the event occurred.

Since the event is an instance of ActionEvent, the TextField class's processEvent method examines the event and passes it along to processActionEvent. The latter method redirects the event to any ActionListener objects that have registered an interest in action events generated by this text field.

Since:
JDK1.0
Version:
1.43, 06/29/98
See Also:
java.awt.event.ActionEvent, processEvent, processActionEvent, Serialized Form

Inner classes inherited from class java.awt.Component
Component.NativeInLightFixer
 
Field Summary
ActionListener actionListener
           
static String base
           
int columns
          The number of columns in the TextField.
char echoChar
          The echo character.
static int nameCounter
           
static long serialVersionUID
           
int textFieldSerializedDataVersion
           
 
Fields inherited from class java.awt.TextComponent
editable, selectionEnd, selectionStart, serialVersionUID, textComponentSerializedDataVersion, textListener, text
 
Fields inherited from class java.awt.Component
actionListenerK, adjustmentListenerK, assert, background, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, changeSupport, componentListener, componentListenerK, componentOrientation, componentSerializedDataVersion, containerListenerK, cursor, dropTarget, enabled, eventMask, focusListener, focusListenerK, font, foreground, hasFocus, height, incRate, inputMethodListener, inputMethodListenerK, isInc, itemListenerK, keyListener, keyListenerK, LEFT_ALIGNMENT, locale, LOCK, minSize, mouseListener, mouseListenerK, mouseMotionListener, mouseMotionListenerK, name, nameExplicitlySet, newEventsOnly, parent, peer, popups, prefSize, RIGHT_ALIGNMENT, serialVersionUID, textListenerK, TOP_ALIGNMENT, valid, visible, width, windowListenerK, x, y
 
Constructor Summary
TextField()
          Constructs a new text field.
TextField(String text)
          Constructs a new text field initialized with the specified text.
TextField(int columns)
          Constructs a new empty TextField with the specified number of columns.
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 characters.
 
Method Summary
void addActionListener(ActionListener l)
          Adds the specified action listener to recieve action events from this text field.
void addNotify()
          Creates the TextField's peer.
String constructComponentName()
          Construct a name for this component.
boolean echoCharIsSet()
          Indicates whether or not this text field has a character set for echoing.
boolean eventEnabled(AWTEvent e)
           
int getColumns()
          Gets the number of columns in this text field.
char getEchoChar()
          Gets the character that is to be used for echoing.
java.awt.Dimension getMinimumSize(int columns)
          Gets the minumum dimensions for a text field with the specified number of columns.
java.awt.Dimension getMinimumSize()
          Gets the minumum dimensions for this text field.
java.awt.Dimension getPreferredSize(int columns)
          Gets the preferred size of this text field with the specified number of columns.
java.awt.Dimension getPreferredSize()
          Gets the preferred size of this text field.
java.awt.Dimension minimumSize(int columns)
          Deprecated.  
java.awt.Dimension minimumSize()
          Deprecated.  
String paramString()
          Returns the parameter string representing the state of this text field.
java.awt.Dimension preferredSize(int columns)
          Deprecated.  
java.awt.Dimension preferredSize()
          Deprecated.  
void processActionEvent(java.awt.event.ActionEvent e)
          Processes action events occurring on this text field by dispatching them to any registered ActionListener objects.
void processEvent(AWTEvent e)
          Processes events on this text field.
void readObject(java.io.ObjectInputStream s)
           
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 setEchoCharacter(char c)
          Deprecated.  
void setEchoChar(char c)
          Sets the echo character for this text field.
void writeObject(java.io.ObjectOutputStream s)
           
 
Methods inherited from class java.awt.TextComponent
addTextListener, areInputMethodsEnabled, enableInputMethodsIfNecessary, eventEnabled, getCaretPosition, getSelectedText, getSelectionEnd, getSelectionStart, getText, isEditable, paramString, processEvent, processTextEvent, readObject, removeNotify, removeTextListener, selectAll, select, setCaretPosition, setEditable, setSelectionEnd, setSelectionStart, setText, writeObject
 
Methods inherited from class java.awt.Component
, action, add, addComponentListener, addFocusListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, areInputMethodsEnabled, bounds, checkImage, checkImage, coalesceEvents, constructComponentName, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, dispatchEventImpl, doLayout, enable, enable, enableEvents, enableInputMethods, ensureWindowActivation, eventEnabled, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getNativeContainer, getParent, getPeer, getPreferredSize, getSize, getSize, getToolkit, getTreeLock, getWidth, getWindowForObject, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, initIDs, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, paint, paramString, postEvent, postsOldMouseEvents, preferredSize, prepareImage, prepareImage, printAll, print, processComponentEvent, processEvent, processFocusEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, readObject, remove, removeComponentListener, removeFocusListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate, writeObject
 
Methods inherited from class java.lang.Object
, clone, equals, finalize, getClass, hashCode, notifyAll, notify, registerNatives, toString, wait, wait, wait
 

Field Detail

columns

int columns
The number of columns in the TextField.

echoChar

char echoChar
The echo character.

actionListener

transient ActionListener actionListener

base

private static final String base

nameCounter

private static int nameCounter

serialVersionUID

private static final long serialVersionUID

textFieldSerializedDataVersion

private int textFieldSerializedDataVersion
Constructor Detail

TextField

public TextField()
Constructs a new text field.

TextField

public TextField(String text)
Constructs a new text field initialized with the specified text.
Parameters:
text - the text to be displayed.

TextField

public TextField(int columns)
Constructs a new empty TextField with the specified number of columns.
Parameters:
columns - the number of columns

TextField

public 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 characters.
Parameters:
text - the text to be displayed.
columns - the number of characters.
Method Detail

constructComponentName

String constructComponentName()
Construct a name for this component. Called by getName() when the name is null.
Overrides:
constructComponentName in class Component

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 class Component

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.

Returns:
the echo character for this text field.
See Also:
echoCharIsSet, setEchoChar


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.

Parameters:
c - the echo character for this text field.
See Also:
echoCharIsSet, getEchoChar


setEchoCharacter

public void setEchoCharacter(char c)
Deprecated. As of JDK version 1.1, replaced by setEchoChar(char).

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, getEchoChar


getColumns

public int getColumns()
Gets the number of columns in this text field.
Returns:
the number of columns.
See Also:
setColumns

setColumns

public void setColumns(int columns)
Sets the number of columns in this text field.
Parameters:
columns - the number of columns.
Throws:
java.lang.IllegalArgumentException - if the value supplied for columns is less than zero.
See Also:
getColumns

getPreferredSize

public java.awt.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.

preferredSize

public java.awt.Dimension preferredSize(int columns)
Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int).

getPreferredSize

public java.awt.Dimension getPreferredSize()
Gets the preferred size of this text field.
Returns:
the preferred dimensions for displaying this text field.
Overrides:
getPreferredSize in class Component

preferredSize

public java.awt.Dimension preferredSize()
Deprecated. As of JDK version 1.1, replaced by getPreferredSize().
Overrides:
preferredSize in class Component

getMinimumSize

public java.awt.Dimension getMinimumSize(int columns)
Gets the minumum dimensions for a text field with the specified number of columns.
Parameters:
columns - the number of columns in this text field.

minimumSize

public java.awt.Dimension minimumSize(int columns)
Deprecated. As of JDK version 1.1, replaced by getMinimumSize(int).

getMinimumSize

public java.awt.Dimension getMinimumSize()
Gets the minumum dimensions for this text field.
Returns:
the minimum dimensions for displaying this text field.
Overrides:
getMinimumSize in class Component

minimumSize

public java.awt.Dimension minimumSize()
Deprecated. As of JDK version 1.1, replaced by getMinimumSize().
Overrides:
minimumSize in class Component

addActionListener

public void addActionListener(ActionListener l)
Adds the specified action listener to recieve action events from this text field.
Parameters:
l - the action listener.
See Also:
java.awt.event#ActionListener, removeActionListener

removeActionListener

public void removeActionListener(ActionListener l)
Removes the specified action listener so that it no longer receives action events from this text field.
Parameters:
l - the action listener.
See Also:
java.awt.event#ActionListener, addActionListener

eventEnabled

boolean eventEnabled(AWTEvent e)
Overrides:
eventEnabled in class TextComponent

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.
Parameters:
e - the event.
Overrides:
processEvent in class TextComponent
See Also:
java.awt.event.ActionEvent, processActionEvent

processActionEvent

protected void processActionEvent(java.awt.event.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:

Parameters:
e - the action event.
See Also:
ActionListener, addActionListener, enableEvents


paramString

protected String paramString()
Returns the parameter string representing the state of this text field. This string is useful for debugging.
Returns:
the parameter string of this text field.
Overrides:
paramString in class TextComponent

writeObject

private void writeObject(java.io.ObjectOutputStream s)
                 throws java.io.IOException
Overrides:
writeObject in class TextComponent

readObject

private void readObject(java.io.ObjectInputStream s)
                throws java.lang.ClassNotFoundException,
                       java.io.IOException
Overrides:
readObject in class TextComponent

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