* Buttons can be configured, and to some degree controlled, by
* Actions. Using an
* Action with a button has many benefits beyond directly
* configuring a button. Refer to
* Swing Components Supporting Action for more
* details, and you can find more information in How
* to Use Actions, a section in The Java Tutorial.
*
* See How to Use Buttons, Check Boxes, and Radio Buttons * in The Java Tutorial * for information and examples of using buttons. *
* Warning: Swing is not thread safe. For more * information see Swing's Threading * Policy. *
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*
* @beaninfo
* attribute: isContainer false
* description: An implementation of a \"push\" button.
*
* @author Jeff Dinkins
*/
public class JButton extends AbstractButton implements Accessible {
/**
* @see #getUIClassID
* @see #readObject
*/
private static final String uiClassID = "ButtonUI";
/**
* Creates a button with no set text or icon.
*/
public JButton() {
this(null, null);
}
/**
* Creates a button with an icon.
*
* @param icon the Icon image to display on the button
*/
public JButton(Icon icon) {
this(null, icon);
}
/**
* Creates a button with text.
*
* @param text the text of the button
*/
@ConstructorProperties({"text"})
public JButton(String text) {
this(text, null);
}
/**
* Creates a button where properties are taken from the
* Action supplied.
*
* @param a the Action used to specify the new button
*
* @since 1.3
*/
public JButton(Action a) {
this();
setAction(a);
}
/**
* Creates a button with initial text and an icon.
*
* @param text the text of the button
* @param icon the Icon image to display on the button
*/
public JButton(String text, Icon icon) {
// Create the model
setModel(new DefaultButtonModel());
// initialize
init(text, icon);
}
/**
* Resets the UI property to a value from the current look and
* feel.
*
* @see JComponent#updateUI
*/
public void updateUI() {
setUI((ButtonUI)UIManager.getUI(this));
}
/**
* Returns a string that specifies the name of the L&F class
* that renders this component.
*
* @return the string "ButtonUI"
* @see JComponent#getUIClassID
* @see UIDefaults#getUI
* @beaninfo
* expert: true
* description: A string that specifies the name of the L&F class.
*/
public String getUIClassID() {
return uiClassID;
}
/**
* Gets the value of the defaultButton property,
* which if true means that this button is the current
* default button for its JRootPane.
* Most look and feels render the default button
* differently, and may potentially provide bindings
* to access the default button.
*
* @return the value of the defaultButton property
* @see JRootPane#setDefaultButton
* @see #isDefaultCapable
* @beaninfo
* description: Whether or not this button is the default button
*/
public boolean isDefaultButton() {
JRootPane root = SwingUtilities.getRootPane(this);
if (root != null) {
return root.getDefaultButton() == this;
}
return false;
}
/**
* Gets the value of the defaultCapable property.
*
* @return the value of the defaultCapable property
* @see #setDefaultCapable
* @see #isDefaultButton
* @see JRootPane#setDefaultButton
*/
public boolean isDefaultCapable() {
return defaultCapable;
}
/**
* Sets the defaultCapable property,
* which determines whether this button can be
* made the default button for its root pane.
* The default value of the defaultCapable
* property is true unless otherwise
* specified by the look and feel.
*
* @param defaultCapable true if this button will be
* capable of being the default button on the
* RootPane; otherwise false
* @see #isDefaultCapable
* @beaninfo
* bound: true
* attribute: visualUpdate true
* description: Whether or not this button can be the default button
*/
public void setDefaultCapable(boolean defaultCapable) {
boolean oldDefaultCapable = this.defaultCapable;
this.defaultCapable = defaultCapable;
firePropertyChange("defaultCapable", oldDefaultCapable, defaultCapable);
}
/**
* Overrides JComponent.removeNotify to check if
* this button is currently set as the default button on the
* RootPane, and if so, sets the RootPane's
* default button to null to ensure the
* RootPane doesn't hold onto an invalid button reference.
*/
public void removeNotify() {
JRootPane root = SwingUtilities.getRootPane(this);
if (root != null && root.getDefaultButton() == this) {
root.setDefaultButton(null);
}
super.removeNotify();
}
/**
* See readObject() and writeObject() in JComponent for more
* information about serialization in Swing.
*/
private void writeObject(ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
if (getUIClassID().equals(uiClassID)) {
byte count = JComponent.getWriteObjCounter(this);
JComponent.setWriteObjCounter(this, --count);
if (count == 0 && ui != null) {
ui.installUI(this);
}
}
}
/**
* Returns a string representation of this JButton.
* 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 a string representation of this JButton
*/
protected String paramString() {
String defaultCapableString = (defaultCapable ? "true" : "false");
return super.paramString() +
",defaultCapable=" + defaultCapableString;
}
/////////////////
// Accessibility support
////////////////
/**
* Gets the AccessibleContext associated with this
* JButton. For JButtons,
* the AccessibleContext takes the form of an
* AccessibleJButton.
* A new AccessibleJButton instance is created if necessary.
*
* @return an AccessibleJButton that serves as the
* AccessibleContext of this JButton
* @beaninfo
* expert: true
* description: The AccessibleContext associated with this Button.
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleJButton();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* JButton class. It provides an implementation of the
* Java Accessibility API appropriate to button user-interface
* elements.
*
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*/
protected class AccessibleJButton extends AccessibleAbstractButton {
/**
* Get the role of this object.
*
* @return an instance of AccessibleRole describing the role of the
* object
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.PUSH_BUTTON;
}
} // inner class AccessibleJButton
}