FocusListener or
- * FocusAdapter object which registered to receive such events
- * using the Component's addFocusListener method. (
- * FocusAdapter objects implement the FocusListener
- * interface.) Each such listener object gets this FocusEvent when
+ * TextField). The event is passed to every {@code FocusListener} or
+ * {@code FocusAdapter} object which registered to receive such events
+ * using the Component's {@code addFocusListener} method. ({@code
+ * FocusAdapter} objects implement the {@code FocusListener}
+ * interface.) Each such listener object gets this {@code FocusEvent} when
* the event occurs.
* * There are two levels of focus events: permanent and temporary. Permanent @@ -51,6 +52,10 @@ * the FOCUS_GAINED and FOCUS_LOST event ids; the level may be distinguished in * the event using the isTemporary() method. *
+ * Every {@code FocusEvent} records its cause - the reason why this event was + * generated. The cause is assigned during the focus event creation and may be + * retrieved by calling {@link #getCause}. + *
* An unspecified behavior will be caused if the {@code id} parameter
* of any particular {@code FocusEvent} instance is not
* in the range from {@code FOCUS_FIRST} to {@code FOCUS_LAST}.
@@ -66,6 +71,61 @@
public class FocusEvent extends ComponentEvent {
/**
+ * This enum represents the cause of a {@code FocusEvent}- the reason why it
+ * occurred. Possible reasons include mouse events, keyboard focus
+ * traversal, window activation.
+ * If no cause is provided then the reason is {@code UNKNOWN}.
+ *
+ * @since 1.9
+ */
+ public enum Cause {
+ /**
+ * The default value.
+ */
+ UNKNOWN,
+ /**
+ * An activating mouse event.
+ */
+ MOUSE_EVENT,
+ /**
+ * A focus traversal action with unspecified direction.
+ */
+ TRAVERSAL,
+ /**
+ * An up-cycle focus traversal action.
+ */
+ TRAVERSAL_UP,
+ /**
+ * A down-cycle focus traversal action.
+ */
+ TRAVERSAL_DOWN,
+ /**
+ * A forward focus traversal action.
+ */
+ TRAVERSAL_FORWARD,
+ /**
+ * A backward focus traversal action.
+ */
+ TRAVERSAL_BACKWARD,
+ /**
+ * Restoring focus after a focus request has been rejected.
+ */
+ ROLLBACK,
+ /**
+ * A system action causing an unexpected focus change.
+ */
+ UNEXPECTED,
+ /**
+ * An activation of a toplevel window.
+ */
+ ACTIVATION,
+ /**
+ * Clearing global focus owner.
+ */
+ CLEAR_GLOBAL_FOCUS_OWNER
+ }
+
+ /**
* The first number in the range of ids used for focus events.
*/
public static final int FOCUS_FIRST = 1004;
@@ -85,6 +145,8 @@
*/
public static final int FOCUS_LOST = 1 + FOCUS_FIRST; //Event.LOST_FOCUS
+ private final Cause cause;
+
/**
* A focus event can have two different levels, permanent and temporary.
* It will be set to true if some operation takes away the focus
@@ -111,60 +173,102 @@
/*
* JDK 1.1 serialVersionUID
*/
- private static final long serialVersionUID = 523753786457416396L;
+ private static final long serialVersionUID = 523753786457416397L;
/**
- * Constructs a FocusEvent object with the
- * specified temporary state and opposite Component.
- * The opposite Component is the other
- * Component involved in this focus change.
- * For a FOCUS_GAINED event, this is the
- * Component that lost focus. For a
- * FOCUS_LOST event, this is the Component
+ * Constructs a {@code FocusEvent} object with the
+ * specified temporary state and opposite {@code Component} and the
+ * {@code Cause.UNKNOWN} cause.
+ * The opposite {@code Component} is the other
+ * {@code Component} involved in this focus change.
+ * For a {@code FOCUS_GAINED} event, this is the
+ * {@code Component} that lost focus. For a
+ * {@code FOCUS_LOST} event, this is the {@code Component}
* that gained focus. If this focus change occurs with a native
* application, with a Java application in a different VM,
- * or with no other Component, then the opposite
- * Component is null.
+ * or with no other {@code Component}, then the opposite
+ * {@code Component} is {@code null}.
*
This method throws an
- * IllegalArgumentException if source
- * is null.
+ * {@code IllegalArgumentException} if {@code source}
+ * is {@code null}.
*
- * @param source The Component that originated the event
+ * @param source The {@code Component} that originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link FocusEvent}
- * @param temporary Equals true if the focus change is temporary;
- * false otherwise
+ * @param temporary Equals {@code true} if the focus change is temporary;
+ * {@code false} otherwise
* @param opposite The other Component involved in the focus change,
- * or null
- * @throws IllegalArgumentException if source equals {@code null}
+ * or {@code null}
+ * @throws IllegalArgumentException if {@code source} equals {@code null}
* @see #getSource()
* @see #getID()
* @see #isTemporary()
* @see #getOppositeComponent()
+ * @see Cause#UNKNOWN
* @since 1.4
*/
public FocusEvent(Component source, int id, boolean temporary,
Component opposite) {
+ this(source, id, temporary, opposite, Cause.UNKNOWN);
+ }
+
+ /**
+ * Constructs a {@code FocusEvent} object with the
+ * specified temporary state, opposite {@code Component} and the cause.
+ * The opposite {@code Component} is the other
+ * {@code Component} involved in this focus change.
+ * For a {@code FOCUS_GAINED} event, this is the
+ * {@code Component} that lost focus. For a
+ * {@code FOCUS_LOST} event, this is the {@code Component}
+ * that gained focus. If this focus change occurs with a native
+ * application, with a Java application in a different VM,
+ * or with no other {@code Component}, then the opposite
+ * {@code Component} is {@code null}.
+ *
This method throws an
+ * {@code IllegalArgumentException} if {@code source}
+ * is {@code null}.
+ *
+ * @param source The {@code Component} that originated the event
+ * @param id An integer indicating the type of event.
+ * For information on allowable values, see
+ * the class description for {@link FocusEvent}
+ * @param temporary Equals {@code true} if the focus change is temporary;
+ * {@code false} otherwise
+ * @param opposite The other Component involved in the focus change,
+ * or {@code null}
+ * @param cause The focus event cause.
+ * @throws IllegalArgumentException if {@code source} equals {@code null}
+ * or if {@code cause} equals {@code null}
+ * @see #getSource()
+ * @see #getID()
+ * @see #isTemporary()
+ * @see #getOppositeComponent()
+ * @see Cause
+ * @since 1.9
+ */
+ public FocusEvent(Component source, int id, boolean temporary,
+ Component opposite, Cause cause) {
super(source, id);
this.temporary = temporary;
this.opposite = opposite;
+ this.cause = cause;
}
/**
- * Constructs a FocusEvent object and identifies
+ * Constructs a {@code FocusEvent} object and identifies
* whether or not the change is temporary.
*
This method throws an
- * IllegalArgumentException if source
- * is null.
+ * {@code IllegalArgumentException} if {@code source}
+ * is {@code null}.
*
- * @param source The Component that originated the event
+ * @param source The {@code Component} that originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link FocusEvent}
- * @param temporary Equals true if the focus change is temporary;
- * false otherwise
- * @throws IllegalArgumentException if source equals {@code null}
+ * @param temporary Equals {@code true} if the focus change is temporary;
+ * {@code false} otherwise
+ * @throws IllegalArgumentException if {@code source} equals {@code null}
* @see #getSource()
* @see #getID()
* @see #isTemporary()
@@ -174,17 +278,17 @@
}
/**
- * Constructs a FocusEvent object and identifies it
+ * Constructs a {@code FocusEvent} object and identifies it
* as a permanent change in focus.
*
This method throws an
- * IllegalArgumentException if source
- * is null.
+ * {@code IllegalArgumentException} if {@code source}
+ * is {@code null}.
*
- * @param source The Component that originated the event
+ * @param source The {@code Component} that originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link FocusEvent}
- * @throws IllegalArgumentException if source equals {@code null}
+ * @throws IllegalArgumentException if {@code source} equals {@code null}
* @see #getSource()
* @see #getID()
*/
@@ -195,8 +299,8 @@
/**
* Identifies the focus change event as temporary or permanent.
*
- * @return true if the focus change is temporary;
- * false otherwise
+ * @return {@code true} if the focus change is temporary;
+ * {@code false} otherwise
*/
public boolean isTemporary() {
return temporary;
@@ -243,7 +347,16 @@
typeStr = "unknown type";
}
return typeStr + (temporary ? ",temporary" : ",permanent") +
- ",opposite=" + getOppositeComponent();
+ ",opposite=" + getOppositeComponent() + ",cause=" + getCause();
}
+ /**
+ * Returns the event cause.
+ *
+ * @return one of {@link Cause} values
+ * @since 1.9
+ */
+ public final Cause getCause() {
+ return cause;
+ }
}