javafx.scene.command.Command Maven / Gradle / Ivy
/*
* Copyright (c) 2022, JFXcore. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. JFXcore designates this
* particular file as subject to the "Classpath" exception as provided
* in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package javafx.scene.command;
import com.sun.javafx.scene.command.CommandHelper;
import javafx.beans.property.ReadOnlyBooleanProperty;
import javafx.scene.Node;
import javafx.util.Incubating;
/**
* Represents an operation that can be invoked in various ways, such as by clicking a button,
* pressing a key, or typing a shortcut.
*
* See the {@link javafx.scene.command Commanding} documentation for additional information.
*
* @see RelayCommand
* @see TaskCommand
* @see ServiceCommand
* @since JFXcore 18
*/
@Incubating
public abstract class Command {
static {
CommandHelper.setAccessor(new CommandHelper.Accessor() {
@Override
public void attach(Command command, Node node) {
command.onAttached(node);
}
@Override
public void detach(Command command, Node node) {
command.onDetached(node);
}
});
}
/**
* Gets a property that indicates whether the command is currently executable.
*
* @return the {@code executable} property
*/
public abstract ReadOnlyBooleanProperty executableProperty();
/**
* Indicates whether the command is currently executable.
*
* @return {@code true} if the command is executable, {@code false} otherwise
*/
public boolean isExecutable() {
return executableProperty().get();
}
/**
* Executes the command.
*
* @param parameter the parameter that is passed to the command, or {@code null}
* @throws IllegalStateException if the command is not executable
*/
public abstract void execute(Object parameter);
/**
* Occurs when the command is attached to a {@link Node} by binding it to one of the {@code Node}'s events.
*
* When the command is bound to multiple events of a single {@code Node}, this method is only invoked once.
* Note that this method will be invoked once for each {@code Node} to which this command is attached.
*
* Derived classes can override this method to implement logic that the command uses to configure the
* controls to which it is attached. For example, a command implementation could set a control's
* {@link javafx.scene.control.Labeled#textProperty()} to a user-defined value.
* Implementing the {@code onAttached} and {@code onDetached} methods is an alternative to using a
* {@link CommandHandler}. The major difference is that {@code CommandHandler} only applies to specific
* nodes on which the {@code CommandHandler} is set, while overriding {@code onAttached} and
* {@code onDetached} applies to all nodes to which this command is attached.
*
* @param node the node to which this command is attached
*/
protected void onAttached(Node node) {}
/**
* Occurs when the command is detached from a {@link Node}.
*
* This happens when the command is removed from its associated {@link EventBinding}, or if the
* {@code EventBinding} is removed from the {@code Node}.
* When the command is bound to multiple events of a single {@code Node}, the command is only detached
* after the last binding is removed. Note that this method will be invoked once for each {@code Node}
* from which this command is detached.
*
* Derived classes can override this method to roll back changes that were established
* by the {@link #onAttached onAttached} method.
*
* @param node the node to which this command was attached
*/
protected void onDetached(Node node) {}
}