* 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.
*
* @author Sami Shaio
* @see java.awt.event.KeyEvent
* @see java.awt.event.KeyAdapter
* @see java.awt.event.KeyListener
* @see java.awt.event.ActionEvent
* @see java.awt.Component#addKeyListener
* @see java.awt.TextField#processEvent
* @see java.awt.TextField#processActionEvent
* @see java.awt.TextField#addActionListener
* @since JDK1.0
*/
public class TextField extends TextComponent {
/**
* The number of columns in the text field.
* A column is an approximate average character
* width that is platform-dependent.
* Guaranteed to be non-negative.
*
* @serial
* @see #setColumns(int)
* @see #getColumns()
*/
int columns;
/**
* The echo character, which is used when
* the user wishes to disguise the characters
* typed into the text field.
* The disguises are removed if echoChar = 0.
*
* @serial
* @see #getEchoChar()
* @see #setEchoChar(char)
* @see #echoCharIsSet()
*/
char echoChar;
transient ActionListener actionListener;
private static final String base = "textfield";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -2966288784432217853L;
/**
* Initialize JNI field and method ids
*/
private static native void initIDs();
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
}
/**
* Constructs a new text field.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public TextField() throws HeadlessException {
this("", 0);
}
/**
* Constructs a new text field initialized with the specified text.
* @param text the text to be displayed. If
* text is null, the empty
* string "" will be displayed.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public TextField(String text) throws HeadlessException {
this(text, (text != null) ? text.length() : 0);
}
/**
* Constructs a new empty text field with the specified number
* of columns. A column is an approximate average character
* width that is platform-dependent.
* @param columns the number of columns. If
* columns is less than 0,
* columns is set to 0.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public TextField(int columns) throws HeadlessException {
this("", columns);
}
/**
* 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.
* @param text the text to be displayed. If
* text is null, the empty
* string "" will be displayed.
* @param columns the number of columns. If
* columns is less than 0,
* columns is set to 0.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public TextField(String text, int columns) throws HeadlessException {
super(text);
this.columns = (columns >= 0) ? columns : 0;
}
/**
* Construct a name for this component. Called by getName() when the
* name is null.
*/
String constructComponentName() {
synchronized (TextField.class) {
return base + nameCounter++;
}
}
/**
* Creates the TextField's peer. The peer allows us to modify the
* appearance of the TextField without changing its functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getToolkit().createTextField(this);
super.addNotify();
}
}
/**
* 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. * @return the echo character for this text field. * @see java.awt.TextField#echoCharIsSet * @see java.awt.TextField#setEchoChar */ public char getEchoChar() { return echoChar; } /** * 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.
* @param c the echo character for this text field.
* @see java.awt.TextField#echoCharIsSet
* @see java.awt.TextField#getEchoChar
* @since JDK1.1
*/
public void setEchoChar(char c) {
setEchoCharacter(c);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by setEchoChar(char).
*/
@Deprecated
public synchronized void setEchoCharacter(char c) {
if (echoChar != c) {
echoChar = c;
TextFieldPeer peer = (TextFieldPeer)this.peer;
if (peer != null) {
peer.setEchoChar(c);
}
}
}
/**
* Sets the text that is presented by this
* text component to be the specified text.
* @param t the new text.
* @see java.awt.TextComponent#getText
*/
public void setText(String t) {
super.setText(t);
// This could change the preferred size of the Component.
invalidateIfValid();
}
/**
* 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.
* @return true if this text field has
* a character set for echoing;
* false otherwise.
* @see java.awt.TextField#setEchoChar
* @see java.awt.TextField#getEchoChar
*/
public boolean echoCharIsSet() {
return echoChar != 0;
}
/**
* Gets the number of columns in this text field. A column is an
* approximate average character width that is platform-dependent.
* @return the number of columns.
* @see java.awt.TextField#setColumns
* @since JDK1.1
*/
public int getColumns() {
return columns;
}
/**
* Sets the number of columns in this text field. A column is an
* approximate average character width that is platform-dependent.
* @param columns the number of columns.
* @see java.awt.TextField#getColumns
* @exception IllegalArgumentException if the value
* supplied for columns
* is less than 0.
* @since JDK1.1
*/
public void setColumns(int columns) {
int oldVal;
synchronized (this) {
oldVal = this.columns;
if (columns < 0) {
throw new IllegalArgumentException("columns less than zero.");
}
if (columns != oldVal) {
this.columns = columns;
}
}
if (columns != oldVal) {
invalidate();
}
}
/**
* Gets the preferred size of this text field
* with the specified number of columns.
* @param columns the number of columns
* in this text field.
* @return the preferred dimensions for
* displaying this text field.
* @since JDK1.1
*/
public Dimension getPreferredSize(int columns) {
return preferredSize(columns);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by getPreferredSize(int).
*/
@Deprecated
public Dimension preferredSize(int columns) {
synchronized (getTreeLock()) {
TextFieldPeer peer = (TextFieldPeer)this.peer;
return (peer != null) ?
peer.getPreferredSize(columns) :
super.preferredSize();
}
}
/**
* Gets the preferred size of this text field.
* @return the preferred dimensions for
* displaying this text field.
* @since JDK1.1
*/
public Dimension getPreferredSize() {
return preferredSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by getPreferredSize().
*/
@Deprecated
public Dimension preferredSize() {
synchronized (getTreeLock()) {
return (columns > 0) ?
preferredSize(columns) :
super.preferredSize();
}
}
/**
* Gets the minumum dimensions for a text field with
* the specified number of columns.
* @param columns the number of columns in
* this text field.
* @since JDK1.1
*/
public Dimension getMinimumSize(int columns) {
return minimumSize(columns);
}
/**
* @deprecated As of JDK version 1.1,
* replaced by getMinimumSize(int).
*/
@Deprecated
public Dimension minimumSize(int columns) {
synchronized (getTreeLock()) {
TextFieldPeer peer = (TextFieldPeer)this.peer;
return (peer != null) ?
peer.getMinimumSize(columns) :
super.minimumSize();
}
}
/**
* Gets the minumum dimensions for this text field.
* @return the minimum dimensions for
* displaying this text field.
* @since JDK1.1
*/
public Dimension getMinimumSize() {
return minimumSize();
}
/**
* @deprecated As of JDK version 1.1,
* replaced by getMinimumSize().
*/
@Deprecated
public Dimension minimumSize() {
synchronized (getTreeLock()) {
return (columns > 0) ?
minimumSize(columns) :
super.minimumSize();
}
}
/**
* 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. * * @param l the action listener. * @see #removeActionListener * @see #getActionListeners * @see java.awt.event.ActionListener * @since JDK1.1 */ public synchronized void addActionListener(ActionListener l) { if (l == null) { return; } actionListener = AWTEventMulticaster.add(actionListener, l); newEventsOnly = true; } /** * 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.
*
* @param l the action listener.
* @see #addActionListener
* @see #getActionListeners
* @see java.awt.event.ActionListener
* @since JDK1.1
*/
public synchronized void removeActionListener(ActionListener l) {
if (l == null) {
return;
}
actionListener = AWTEventMulticaster.remove(actionListener, l);
}
/**
* Returns an array of all the action listeners
* registered on this textfield.
*
* @return all of this textfield's ActionListeners
* or an empty array if no action
* listeners are currently registered
*
* @see #addActionListener
* @see #removeActionListener
* @see java.awt.event#ActionListener
* @since 1.4
*/
public synchronized ActionListener[] getActionListeners() {
return (ActionListener[])(getListeners(ActionListener.class));
}
/**
* Returns an array of all the objects currently registered
* as 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. * * @param listenerType the type of listeners requested; this parameter * should specify an interface that descends from *
java.util.EventListener
* @return an array of all objects registered as
* FooListeners on this textfield,
* or an empty array if no such
* listeners have been added
* @exception ClassCastException if listenerType
* doesn't specify a class or interface that implements
* java.util.EventListener
*
* @see #getActionListeners
* @since 1.3
*/
public 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.
*
* @param e the event
* @see java.awt.event.ActionEvent
* @see java.awt.TextField#processActionEvent
* @since JDK1.1
*/
protected void processEvent(AWTEvent e) {
if (e instanceof ActionEvent) {
processActionEvent((ActionEvent)e);
return;
}
super.processEvent(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: *
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.
*
* @param e the action event
* @see java.awt.event.ActionListener
* @see java.awt.TextField#addActionListener
* @see java.awt.Component#enableEvents
* @since JDK1.1
*/
protected void processActionEvent(ActionEvent e) {
ActionListener listener = actionListener;
if (listener != null) {
listener.actionPerformed(e);
}
}
/**
* 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.
*
* @return the parameter string of this text field
*/
protected String paramString() {
String str = super.paramString();
if (echoChar != 0) {
str += ",echo=" + echoChar;
}
return str;
}
/*
* Serialization support.
*/
/**
* The textField Serialized Data Version.
*
* @serial
*/
private int textFieldSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream. Writes
* a list of serializable ActionListener(s) as optional data.
* The non-serializable ActionListener(s) are detected and
* no attempt is made to serialize them.
*
* @serialData Null terminated sequence of zero or more pairs.
* A pair consists of a String and Object.
* The String indicates the type of object and
* is one of the following :
* ActionListenerK indicating and ActionListener object.
*
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see java.awt.Component#actionListenerK
*/
private void writeObject(ObjectOutputStream s)
throws IOException
{
s.defaultWriteObject();
AWTEventMulticaster.save(s, actionListenerK, actionListener);
s.writeObject(null);
}
/**
* Read the ObjectInputStream and if it isn't null,
* add a listener to receive action events fired by the
* TextField. Unrecognized keys or values will be
* ignored.
*
* @exception HeadlessException if
* GraphicsEnvironment.isHeadless() returns
* true
* @see #removeActionListener(ActionListener)
* @see #addActionListener(ActionListener)
* @see java.awt.GraphicsEnvironment#isHeadless
*/
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException, HeadlessException
{
// HeadlessException will be thrown by TextComponent's readObject
s.defaultReadObject();
// Make sure the state we just read in for columns has legal values
if (columns < 0) {
columns = 0;
}
// Read in listeners, if any
Object keyOrNull;
while(null != (keyOrNull = s.readObject())) {
String key = ((String)keyOrNull).intern();
if (actionListenerK == key) {
addActionListener((ActionListener)(s.readObject()));
} else {
// skip value for unrecognized key
s.readObject();
}
}
}
/////////////////
// Accessibility support
////////////////
/**
* 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.
*
* @return an AccessibleAWTTextField that serves as the
* AccessibleContext of this TextField
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleAWTTextField();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* TextField class. It provides an implementation of the
* Java Accessibility API appropriate to text field user-interface elements.
* @since 1.3
*/
protected class AccessibleAWTTextField extends AccessibleAWTTextComponent
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = 6219164359235943158L;
/**
* Gets the state set of this object.
*
* @return an instance of AccessibleStateSet describing the states
* of the object
* @see AccessibleState
*/
public AccessibleStateSet getAccessibleStateSet() {
AccessibleStateSet states = super.getAccessibleStateSet();
states.add(AccessibleState.SINGLE_LINE);
return states;
}
}
}