/**
* Constructs a Checkbox with the specified label, set to the specified state, and in the
* specified check box group.
*
* @param label a string label for this check box, or <code>null</code> for no label.
* @param state the initial state of this check box.
* @param group a check box group for this check box, or <code>null</code> for no group.
* @exception HeadlessException if <code>GraphicsEnvironment.isHeadless</code> returns <code>true
* </code>
* @see j86.java.awt.GraphicsEnvironment#isHeadless
* @since JDK1.1
*/
public Checkbox(String label, boolean state, CheckboxGroup group) throws HeadlessException {
GraphicsEnvironment.checkHeadless();
this.label = label;
this.state = state;
this.group = group;
if (state && (group != null)) {
group.setSelectedCheckbox(this);
}
}
/**
* Sets the state of this check box to the specified state. The boolean value <code>true</code>
* indicates the "on" state, and <code>false</code> indicates the "off" state.
*
* <p>Note that this method should be primarily used to initialize the state of the checkbox.
* Programmatically setting the state of the checkbox will <i>not</i> trigger an <code>ItemEvent
* </code>. The only way to trigger an <code>ItemEvent</code> is by user interaction.
*
* @param state the boolean state of the check box
* @see #getState
*/
public void setState(boolean state) {
/* Cannot hold check box lock when calling group.setSelectedCheckbox. */
CheckboxGroup group = this.group;
if (group != null) {
if (state) {
group.setSelectedCheckbox(this);
} else if (group.getSelectedCheckbox() == this) {
state = true;
}
}
setStateInternal(state);
}
/**
* Sets this check box's group to the specified check box group. If this check box is already in a
* different check box group, it is first taken out of that group.
*
* <p>If the state of this check box is <code>true</code> and the new group already has a check
* box selected, this check box's state is changed to <code>false</code>. If the state of this
* check box is <code>true</code> and the new group has no check box selected, this check box
* becomes the selected checkbox for the new group and its state is <code>true</code>.
*
* @param g the new check box group, or <code>null</code> to remove this check box from any check
* box group
* @see #getCheckboxGroup
*/
public void setCheckboxGroup(CheckboxGroup g) {
CheckboxGroup oldGroup;
boolean oldState;
/* Do nothing if this check box has already belonged
* to the check box group g.
*/
if (this.group == g) {
return;
}
synchronized (this) {
oldGroup = this.group;
oldState = getState();
this.group = g;
CheckboxPeer peer = (CheckboxPeer) this.peer;
if (peer != null) {
peer.setCheckboxGroup(g);
}
if (this.group != null && getState()) {
if (this.group.getSelectedCheckbox() != null) {
setState(false);
} else {
this.group.setSelectedCheckbox(this);
}
}
}
/* Locking check box below could cause deadlock with
* CheckboxGroup's setSelectedCheckbox method.
*
* Fix for 4726853 by [email protected]
* Here we should check if this check box was selected
* in the previous group and set selected check box to
* null for that group if so.
*/
if (oldGroup != null && oldState) {
oldGroup.setSelectedCheckbox(null);
}
}