org.apache.commons.collections15.keyvalue.KeyedAccessUtils.java Source code

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Here is the source code for org.apache.commons.collections15.keyvalue.KeyedAccessUtils.java

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/*
 * Copyright 2013 Lyor Goldstein
 * 
 * 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 org.apache.commons.collections15.keyvalue;

import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Properties;

import org.apache.commons.collections15.ExtendedMapUtils;
import org.apache.commons.lang3.ExtendedStringUtils;

/**
 * @author Lyor G.
 * @since Jun 4, 2013 11:46:09 AM
 */
public class KeyedAccessUtils {
    @SuppressWarnings("rawtypes")
    private static final EnumerableKeyedReader emptyReader = new EnumerableKeyedReader() {
        @Override
        public Collection getKeys() {
            return Collections.emptyList();
        }

        @Override
        public Object get(Object key) {
            return null;
        }
    };

    /**
     * @return An {@link EnumerableKeyedReader} that returns an empty
     * {@link Collection} of keys and also <code>null</code> on any
     * invocation of the <code>get</code> method with any key
     */
    @SuppressWarnings("unchecked")
    public static final <K, V> EnumerableKeyedReader<K, V> emptyReader() {
        return emptyReader;
    }

    public static final <K, V> EnumerableKeyedAccessor<K, V> keyedAccessor(final Map<K, V> map) {
        return new EnumerableKeyedAccessor<K, V>() {
            @Override
            public Collection<K> getKeys() {
                return Collections.unmodifiableSet(map.keySet());
            }

            @Override
            public V get(K key) {
                if (ExtendedMapUtils.isEmpty(map)) {
                    return null;
                } else {
                    return map.get(key);
                }
            }

            @Override
            public V put(K key, V value) {
                return map.put(key, value);
            }
        };
    }

    public static final ExtendedEnumerableKeyedAccessor<String, String> keyedAccessor(final Properties props) {
        return new AbstractExtendedEnumerableKeyedAccessor<String, String>(String.class, String.class) {
            @Override
            public Collection<String> getKeys() {
                return Collections.unmodifiableSet(props.stringPropertyNames());
            }

            @Override
            public String get(String key) {
                return props.getProperty(key);
            }

            @Override
            public String put(String key, String value) {
                return ExtendedStringUtils.safeToString(props.setProperty(key, value));
            }
        };
    }
}