src/java.desktop/share/classes/javax/swing/plaf/basic/LazyActionMap.java

/*
 * Copyright (c) 2002, 2022, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.swing.plaf.basic;

import java.lang.reflect.*;
import javax.swing.*;
import javax.swing.plaf.*;

/**
 * An ActionMap that populates its contents as necessary. The
 * contents are populated by invoking the <code>loadActionMap</code>
 * method on the passed in Object.
 *
 * @author Scott Violet
 */
@SuppressWarnings("serial") // Same-version serialization only
class LazyActionMap extends ActionMapUIResource {
    /**
     * Object to invoke <code>loadActionMap</code> on. This may be
     * a Class object.
     */
    private transient Object _loader;

    /**
     * Installs an ActionMap that will be populated by invoking the
     * <code>loadActionMap</code> method on the specified Class
     * when necessary.
     * <p>
     * This should be used if the ActionMap can be shared.
     *
     * @param c JComponent to install the ActionMap on.
     * @param loaderClass Class object that gets loadActionMap invoked
     *                    on.
     * @param defaultsKey Key to use to defaults table to check for
     *        existing map and what resulting Map will be registered on.
     */
    static void installLazyActionMap(JComponent c, Class<?> loaderClass,
                                     String defaultsKey) {
        ActionMap map = (ActionMap)UIManager.get(defaultsKey);
        if (map == null) {
            map = new LazyActionMap(loaderClass);
            UIManager.getLookAndFeelDefaults().put(defaultsKey, map);
        }
        SwingUtilities.replaceUIActionMap(c, map);
    }

    /**
     * Returns an ActionMap that will be populated by invoking the
     * <code>loadActionMap</code> method on the specified Class
     * when necessary.
     * <p>
     * This should be used if the ActionMap can be shared.
     *
     * @param loaderClass Class object that gets loadActionMap invoked
     *                    on.
     * @param defaultsKey Key to use to defaults table to check for
     *        existing map and what resulting Map will be registered on.
     */
    static ActionMap getActionMap(Class<?> loaderClass,
                                  String defaultsKey) {
        ActionMap map = (ActionMap)UIManager.get(defaultsKey);
        if (map == null) {
            map = new LazyActionMap(loaderClass);
            UIManager.getLookAndFeelDefaults().put(defaultsKey, map);
        }
        return map;
    }


    private LazyActionMap(Class<?> loader) {
        _loader = loader;
    }

    public void put(Action action) {
        put(action.getValue(Action.NAME), action);
    }

    public void put(Object key, Action action) {
        loadIfNecessary();
        super.put(key, action);
    }

    public Action get(Object key) {
        loadIfNecessary();
        return super.get(key);
    }

    public void remove(Object key) {
        loadIfNecessary();
        super.remove(key);
    }

    public void clear() {
        loadIfNecessary();
        super.clear();
    }

    public Object[] keys() {
        loadIfNecessary();
        return super.keys();
    }

    public int size() {
        loadIfNecessary();
        return super.size();
    }

    public Object[] allKeys() {
        loadIfNecessary();
        return super.allKeys();
    }

    public void setParent(ActionMap map) {
        loadIfNecessary();
        super.setParent(map);
    }

    private void loadIfNecessary() {
        if (_loader != null) {
            Object loader = _loader;

            _loader = null;
            Class<?> klass = (Class<?>)loader;
            try {
                Method method = klass.getDeclaredMethod("loadActionMap",
                                      new Class<?>[] { LazyActionMap.class });
                method.invoke(klass, new Object[] { this });
            } catch (NoSuchMethodException nsme) {
                assert false : "LazyActionMap unable to load actions " +
                        klass;
            } catch (IllegalAccessException | IllegalArgumentException |
                     InvocationTargetException e) {
                assert false : "LazyActionMap unable to load actions " +
                        e;
            }
        }
    }
}