Java Doc for TextField.java in  » 6.0-JDK-Core » AWT » java » awt » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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.
version:
   1.92, 05/05/07
author:
   Sami Shaio
See Also:   java.awt.event.KeyEvent
See Also:   java.awt.event.KeyAdapter
See Also:   java.awt.event.KeyListener
See Also:   java.awt.event.ActionEvent
See Also:   java.awt.Component.addKeyListener
See Also:   java.awt.TextField.processEvent
See Also:   java.awt.TextField.processActionEvent
See Also:   java.awt.TextField.addActionListener
since:
   JDK1.0

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.

This method is not called unless action events are enabled for this component.

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.

Refer to AWT Threading Issues for details on AWT's threading model.
Parameters:
  l - the action listener.
See Also:   TextField.removeActionListener
See Also:   TextField.getActionListeners
See Also:   java.awt.event.ActionListener
since:
   JDK1.1

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 hasa character set for echoing;false otherwise.
See Also:   java.awt.TextField.setEchoChar
See Also:   java.awt.TextField.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. the echo character for this text field.
See Also:   java.awt.TextField.echoCharIsSet
See Also:   java.awt.TextField.setEchoChar

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));

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 via addActionListener.
• 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
See Also:   java.awt.event.ActionListener
See Also:   java.awt.TextField.addActionListener
See Also:   java.awt.Component.enableEvents
since:
   JDK1.1

Note that if the event parameter is null the behavior is unspecified and may result in an exception.
Parameters:
  e - the event
See Also:   java.awt.event.ActionEvent
See Also:   java.awt.TextField.processActionEvent
since:
   JDK1.1

Refer to AWT Threading Issues for details on AWT's threading model.
Parameters:
  l - the action listener.
See Also:   TextField.addActionListener
See Also:   TextField.getActionListeners
See Also:   java.awt.event.ActionListener
since:
   JDK1.1

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.
See Also:   java.awt.TextField.echoCharIsSet
See Also:   java.awt.TextField.getEchoChar
since:
   JDK1.1