com.google.gwt.place.shared.PlaceChangeRequestEvent Maven / Gradle / Ivy
/*
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.place.shared;
import com.google.gwt.event.shared.EventHandler;
import com.google.gwt.event.shared.GwtEvent;
/**
* Event thrown when the user may go to a new place in the app, or tries to
* leave it. Receivers can call {@link #setWarning(String)} request that the
* user be prompted to confirm the change.
*/
public class PlaceChangeRequestEvent extends
GwtEvent {
/**
* Implemented by handlers of PlaceChangeRequestEvent.
*/
public interface Handler extends EventHandler {
/**
* Called when a {@link PlaceChangeRequestEvent} is fired.
*
* @param event the {@link PlaceChangeRequestEvent}
*/
void onPlaceChangeRequest(PlaceChangeRequestEvent event);
}
/**
* A singleton instance of Type<Handler>.
*/
public static final Type TYPE = new Type();
private String warning;
private final Place newPlace;
/**
* Constructs a PlaceChangeRequestEvent for the given {@link Place}.
*
* @param newPlace a {@link Place} instance
*/
public PlaceChangeRequestEvent(Place newPlace) {
this.newPlace = newPlace;
}
@Override
public Type getAssociatedType() {
return TYPE;
}
/**
* Returns the place we may navigate to, or null on window close.
*
* @return a {@link Place} instance
*/
public Place getNewPlace() {
return newPlace;
}
/**
* Returns the warning message to show the user before allowing the place
* change, or null if none has been set.
*
* @return the warning message as a String
* @see #setWarning(String)
*/
public String getWarning() {
return warning;
}
/**
* Set a message to warn the user that it might be unwise to navigate away
* from the current place, e.g. due to unsaved changes. If the user clicks
* okay to that message, navigation will be canceled.
*
* Calling with a null warning is the same as not calling the method at all --
* the user will not be prompted.
*
* Only the first non-null call to setWarning has any effect. That is, once
* the warning message has been set it cannot be cleared.
*
* @param warning the warning message as a String
* @see #getWarning()
*/
public void setWarning(String warning) {
if (this.warning == null) {
this.warning = warning;
}
}
@Override
protected void dispatch(Handler handler) {
handler.onPlaceChangeRequest(this);
}
}