Class TextComponent

The TextComponent class is the superclass of any component that allows the editing of some text.

A text component embodies a string of text. The TextComponent class defines a set of methods that determine whether or not this text is editable. If the component is editable, it defines another set of methods that supports a text insertion caret.

In addition, the class defines methods that are used to maintain a current selection from the text. The text selection, a substring of the component's text, is the target of editing operations. It is also referred to as the selected text.

Fields

textListener

protected transient TextListener textListener

Methods

enableInputMethods

public void enableInputMethods(boolean enable)

Enables or disables input method support for this text component. If input method support is enabled and the text component also processes key events, incoming events are offered to the current input method and will only be processed by the component or dispatched to its listeners if the input method does not consume them. Whether and how input method support for this text component is enabled or disabled by default is implementation dependent.

Overrides:

enableInputMethods in class Component

Parameters:

enable - true to enable, false to disable

Since:

1.2

See Also:

Component.processKeyEvent(java.awt.event.KeyEvent)

getInputMethodRequests

public InputMethodRequests getInputMethodRequests()

Description copied from class: Component

Gets the input method request handler which supports requests from input methods for this component. A component that supports on-the-spot text input must override this method to return an InputMethodRequests instance. At the same time, it also has to handle input method events.

Overrides:

getInputMethodRequests in class Component

Returns:

the input method request handler for this component, null by default

See Also:

Component.addInputMethodListener(java.awt.event.InputMethodListener)

addNotify

public void addNotify()

Makes this Component displayable by connecting it to a native screen resource. This method is called internally by the toolkit and should not be called directly by programs.

Overrides:

addNotify in class Component

See Also:

removeNotify()

removeNotify

public void removeNotify()

Removes the TextComponent's peer. The peer allows us to modify the appearance of the TextComponent without changing its functionality.

Overrides:

removeNotify in class Component

See Also:

Component.isDisplayable(), Component.addNotify()

setText

public void setText(String t)

Sets the text that is presented by this text component to be the specified text.

Parameters:

t - the new text; if this parameter is null then the text is set to the empty string ""

See Also:

getText()

getText

public String getText()

Returns the text that is presented by this text component. By default, this is an empty string.

Returns:

the value of this TextComponent

See Also:

setText(java.lang.String)

getSelectedText

public String getSelectedText()

Returns the selected text from the text that is presented by this text component.

Returns:

the selected text of this text component

See Also:

select(int, int)

isEditable

public boolean isEditable()

Indicates whether or not this text component is editable.

Returns:

true if this text component is editable; false otherwise.

Since:

JDK1.0

See Also:

setEditable(boolean)

setEditable

public void setEditable(boolean b)

Parameters:

b - a flag indicating whether this text component is user editable.

Since:

JDK1.0

See Also:

isEditable()

getBackground

public Color getBackground()

Gets the background color of this text component. By default, non-editable text components have a background color of SystemColor.control. This default can be overridden by calling setBackground.

Overrides:

getBackground in class Component

Returns:

This text component's background color. If this text component does not have a background color, the background color of its parent is returned.

Since:

JDK1.0

See Also:

setBackground(Color)

setBackground

public void setBackground(Color c)

Sets the background color of this text component.

Overrides:

setBackground in class Component

Parameters:

c - The color to become this text component's color. If this parameter is null then this text component will inherit the background color of its parent.

Since:

JDK1.0

See Also:

getBackground()

getSelectionStart

public int getSelectionStart()

Gets the start position of the selected text in this text component.

Returns:

the start position of the selected text

See Also:

setSelectionStart(int), getSelectionEnd()

setSelectionStart

public void setSelectionStart(int selectionStart)

Sets the selection start for this text component to the specified position. The new start point is constrained to be at or before the current selection end. It also cannot be set to less than zero, the beginning of the component's text. If the caller supplies a value for selectionStart that is out of bounds, the method enforces these constraints silently, and without failure.

Parameters:

selectionStart - the start position of the selected text

Since:

JDK1.1

See Also:

getSelectionStart(), setSelectionEnd(int)

getSelectionEnd

public int getSelectionEnd()

Gets the end position of the selected text in this text component.

Returns:

the end position of the selected text

See Also:

setSelectionEnd(int), getSelectionStart()

setSelectionEnd

public void setSelectionEnd(int selectionEnd)

Sets the selection end for this text component to the specified position. The new end point is constrained to be at or after the current selection start. It also cannot be set beyond the end of the component's text. If the caller supplies a value for selectionEnd that is out of bounds, the method enforces these constraints silently, and without failure.

Parameters:

selectionEnd - the end position of the selected text

Since:

JDK1.1

See Also:

getSelectionEnd(), setSelectionStart(int)

select

public void select(int selectionStart,
                   int selectionEnd)

Parameters:

selectionStart - the zero-based index of the first character (char value) to be selected

selectionEnd - the zero-based end position of the text to be selected; the character (char value) at selectionEnd is not selected

See Also:

setSelectionStart(int), setSelectionEnd(int), selectAll()

selectAll

public void selectAll()

Selects all the text in this text component.

See Also:

select(int, int)

setCaretPosition

public void setCaretPosition(int position)

Sets the position of the text insertion caret. The caret position is constrained to be between 0 and the last character of the text, inclusive. If the passed-in value is greater than this range, the value is set to the last character (or 0 if the TextComponent contains no text) and no error is returned. If the passed-in value is less than 0, an IllegalArgumentException is thrown.

Parameters:

position - the position of the text insertion caret

Throws:

IllegalArgumentException - if position is less than zero

Since:

JDK1.1

getCaretPosition

public int getCaretPosition()

Returns the position of the text insertion caret. The caret position is constrained to be between 0 and the last character of the text, inclusive. If the text or caret have not been set, the default caret position is 0.

Returns:

the position of the text insertion caret

Since:

JDK1.1

See Also:

setCaretPosition(int)

addTextListener

public void addTextListener(TextListener l)

Parameters:

l - the text event listener

See Also:

removeTextListener(java.awt.event.TextListener), getTextListeners(), TextListener

removeTextListener

public void removeTextListener(TextListener l)

Parameters:

l - the text listener

Since:

JDK1.1

See Also:

addTextListener(java.awt.event.TextListener), getTextListeners(), TextListener

getTextListeners

public TextListener[] getTextListeners()

Returns an array of all the text listeners registered on this text component.

Returns:

all of this text component's TextListeners or an empty array if no text listeners are currently registered

Since:

1.4

See Also:

addTextListener(java.awt.event.TextListener), removeTextListener(java.awt.event.TextListener)

getListeners

public <T extends EventListener> T[] getListeners(Class<T> listenerType)

TextListener[] tls = (TextListener[])(t.getListeners(TextListener.class));

Overrides:

getListeners in class Component

Parameters:

listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener

Returns:

an array of all objects registered as FooListeners on this text component, or an empty array if no such listeners have been added

Throws:

ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener

Since:

1.3

See Also:

getTextListeners()

processEvent

protected void processEvent(AWTEvent e)

Overrides:

processEvent in class Component

Parameters:

e - the event

See Also:

Component.processComponentEvent(java.awt.event.ComponentEvent), Component.processFocusEvent(java.awt.event.FocusEvent), Component.processKeyEvent(java.awt.event.KeyEvent), Component.processMouseEvent(java.awt.event.MouseEvent), Component.processMouseMotionEvent(java.awt.event.MouseEvent), Component.processInputMethodEvent(java.awt.event.InputMethodEvent), Component.processHierarchyEvent(java.awt.event.HierarchyEvent), Component.processMouseWheelEvent(java.awt.event.MouseWheelEvent)

processTextEvent

protected void processTextEvent(TextEvent e)

Parameters:

e - the text event

See Also:

Component.enableEvents(long)

paramString

protected String paramString()

Returns a string representing the state of this TextComponent. 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 class Component

Returns:

the parameter string of this text component

getAccessibleContext

public AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this TextComponent. For text components, the AccessibleContext takes the form of an AccessibleAWTTextComponent. A new AccessibleAWTTextComponent instance is created if necessary.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in class Component

Returns:

an AccessibleAWTTextComponent that serves as the AccessibleContext of this TextComponent

Since:

1.3