unmodifiable Set - Java java.util

Java examples for java.util:Set Operation

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Description

unmodifiable Set

Demo Code

/*//w w w . j  a va  2  s.  c o m
 *
 * This file is part of the XiPKI project.
 * Copyright (c) 2014 - 2015 Lijun Liao
 * Author: Lijun Liao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * THE AUTHOR LIJUN LIAO. LIJUN LIAO DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the XiPKI software without
 * disclosing the source code of your own applications.
 *
 * For more information, please contact Lijun Liao at this
 * address: lijun.liao@gmail.com
 */
//package com.java2s;

import java.util.Collection;
import java.util.Collections;

import java.util.HashSet;

import java.util.Map;
import java.util.Set;

public class Main {
    public static <T> Set<T> unmodifiableSet(final Set<? extends T> s) {
        if (s == null) {
            return null;
        }

        return Collections.unmodifiableSet(s);
    }

    public static <T> Set<T> unmodifiableSet(final Set<? extends T> s,
            final boolean newSet, final boolean emptyAsNull) {
        if (s == null) {
            return null;
        }

        if (emptyAsNull && s.isEmpty()) {
            return null;
        }

        return Collections.unmodifiableSet(newSet ? new HashSet<>(s) : s);
    }

    public static boolean isEmpty(final Collection<?> c) {
        return c == null || c.isEmpty();
    }

    public static boolean isEmpty(final Map<?, ?> m) {
        return m == null || m.isEmpty();
    }
}

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