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/*
* Copyright 2000-2022 Vaadin Ltd.
*
* 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.vaadin.navigator;
import java.util.EventObject;
/**
* Event sent to the View instance before navigating away from it.
* <p>
* Provides a {@link #navigate()} method which must be called for the navigation
* to take place.
*
* @since 8.1
*/
public class ViewBeforeLeaveEvent extends EventObject {
private ViewLeaveAction action;
private boolean navigateRun = false;
/**
* Creates a new event instance for the given navigator.
*
* @param navigator
* the navigator instance
* @param action
* the command to execute when calling {@link #navigate()}
*/
public ViewBeforeLeaveEvent(Navigator navigator, ViewLeaveAction action) {
super(navigator);
this.action = action;
}
/**
* Performs the navigation which triggered the event in the first place.
*/
public void navigate() {
if (navigateRun) {
throw new IllegalStateException(
"navigate() can only be called once");
}
action.run();
navigateRun = true;
}
/**
* Checks if the navigate command has been executed.
*
* @return <code>true</code> if {@link #navigate()} has been called,
* <code>false</code> otherwise
*/
protected boolean isNavigateRun() {
return navigateRun;
}
}
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