Utils.java Source code

Introduction

Here is the source code for Utils.java

Source

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
 * License Header, with the fields enclosed by brackets [] replaced by
 * your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 *
 * Contributor(s):
 *
 * The Original Software is NetBeans. The Initial Developer of the Original
 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
 * Microsystems, Inc. All Rights Reserved.
 *
 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
 * single choice of license, a recipient has the option to distribute
 * your version of this file under either the CDDL, the GPL Version 2 or
 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
 * Version 2 license, then the option applies only if the new code is
 * made subject to such option by the copyright holder.
 */

import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;

/**
 * @since 4.37
 * @author Jaroslav Tulach
 */

public class Utils {
    /**
     * Create a typesafe filter of an unchecked enumeration.
     * @param rawEnum an unchecked enumeration
     * @param type the desired enumeration type
     * @param strict if false, elements which are not null but not assignable to the requested type are omitted;
     *               if true, {@link ClassCastException} may be thrown from an enumeration operation
     * @return an enumeration guaranteed to contain only objects of the requested type (or null)
     */
    public static <E> Enumeration<E> checkedEnumerationByFilter(Enumeration rawEnum, final Class<E> type,
            final boolean strict) {
        @SuppressWarnings("unchecked")
        Enumeration<Object> _rawEnum = rawEnum;
        return Enumerations.<Object, E>filter(_rawEnum, new Enumerations.Processor<Object, E>() {
            public E process(Object o, Collection<Object> ignore) {
                if (o == null) {
                    return null;
                } else {
                    try {
                        return type.cast(o);
                    } catch (ClassCastException x) {
                        if (strict) {
                            throw x;
                        } else {
                            return null;
                        }
                    }
                }
            }
        });
    }

}

abstract class CheckedIterator<E> implements Iterator<E> {

    static final Object WAITING = new Object();

    private final Iterator it;

    private Object next = WAITING;

    public CheckedIterator(Iterator it) {
        this.it = it;
    }

    protected abstract boolean accept(Object o);

    public boolean hasNext() {
        if (next != WAITING) {
            return true;
        }
        while (it.hasNext()) {
            next = it.next();
            if (accept(next)) {
                return true;
            }
        }
        next = WAITING;
        return false;
    }

    public E next() {
        if (next == WAITING && !hasNext()) {
            throw new NoSuchElementException();
        }
        assert next != WAITING;
        @SuppressWarnings("unchecked")
        // type-checking is done by accept()
        E x = (E) next;
        next = WAITING;
        return x;
    }

    public void remove() {
        it.remove();
    }

}