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.
Nested Class Summary | |
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protected class |
TextField.AccessibleAWTTextField
This class implements accessibility support for the TextField class. |
Nested classes/interfaces inherited from class java.awt. TextComponent |
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TextComponent.AccessibleAWTTextComponent |
Nested classes/interfaces inherited from class java.awt. Component |
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Component.AccessibleAWTComponent , Component.BaselineResizeBehavior , Component.BltBufferStrategy , Component.FlipBufferStrategy |
Field Summary |
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Fields inherited from class java.awt. TextComponent |
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textListener |
Fields inherited from class java.awt. Component |
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BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT |
Fields inherited from interface java.awt.image. ImageObserver |
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ABORT , ALLBITS , ERROR , FRAMEBITS , HEIGHT , PROPERTIES , SOMEBITS , WIDTH |
Constructor Summary | |
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TextField
() Constructs a new text field. |
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TextField
(int columns) Constructs a new empty text field with the specified number of columns. |
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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 | ||
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void |
addActionListener
(
ActionListener
l) Adds the specified action listener to receive action events from this text field. |
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void |
addNotify
() Creates the TextField's peer. |
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boolean |
echoCharIsSet
() Indicates whether or not this text field has a character set for echoing. |
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AccessibleContext |
getAccessibleContext
() Gets the AccessibleContext associated with this TextField. |
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ActionListener [] |
getActionListeners
() Returns an array of all the action listeners registered on this textfield. |
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int |
getColumns
() Gets the number of columns in this text field. |
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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. |
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Dimension |
getMinimumSize
() Gets the minumum dimensions for this text field. |
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Dimension |
getMinimumSize
(int columns) Gets the minumum dimensions for a text field with the specified number of columns. |
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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(). |
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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. |
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Dimension |
preferredSize
() Deprecated. As of JDK version 1.1, replaced by getPreferredSize(). |
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Dimension |
preferredSize
(int columns) Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int). |
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protected void |
processActionEvent
(
ActionEvent
e) Processes action events occurring on this text field by dispatching them to any registered ActionListener objects. |
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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. |
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void |
setColumns
(int columns) Sets the number of columns in this text field. |
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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. |
Methods inherited from class java.awt. TextComponent |
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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 |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Constructor Detail |
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public TextField() throws HeadlessException
public TextField(String text) throws HeadlessException
public TextField(int columns) throws HeadlessException
public TextField(String text, int columns) throws HeadlessException
Method Detail |
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public void addNotify()
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.
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.
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.
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.
@Deprecated public void setEchoCharacter(char c)
public void setText(String t)
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.
public int getColumns()
public void setColumns(int columns)
public Dimension getPreferredSize(int columns)
@Deprecated public Dimension preferredSize(int columns)
public Dimension getPreferredSize()
@Deprecated public Dimension preferredSize()
public Dimension getMinimumSize(int columns)
@Deprecated public Dimension minimumSize(int columns)
public Dimension getMinimumSize()
@Deprecated public Dimension minimumSize()
public void addActionListener(ActionListener l)
Refer to
AWT Threading Issues
for details on AWT's threading model.
public void removeActionListener(ActionListener l)
Refer to
AWT Threading Issues
for details on AWT's threading model.
public ActionListener[] getActionListeners()
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
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.
protected void processEvent(AWTEvent e)
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
protected void processActionEvent(ActionEvent e)
This method is not called unless action events are enabled for this component. Action events are enabled when one of the following occurs:
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
protected String paramString()
public AccessibleContext getAccessibleContext()