CollectionsSingletonMapSerializer.java

/*
 * Copyright 2010 Martin Grotzke
 *
 * 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 de.javakaffee.kryoserializers;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.Serializer;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;

/**
 * A kryo {@link Serializer} for {@link List}s created via {@link Collections#singletonMap(Object, Object)}.
 * <p>
 * Note: This serializer does not support cyclic references, if a serialized object
 * is part of a cycle this might cause an error during deserialization.
 * </p>
 * 
 * @author <a href="mailto:martin.grotzke@javakaffee.de">Martin Grotzke</a>
 */
public class CollectionsSingletonMapSerializer extends Serializer<Map<?, ?>> {

    public CollectionsSingletonMapSerializer() {
        setImmutable(true);
    }

    @Override
    public Map<?, ?> read(final Kryo kryo, final Input input, final Class<Map<?, ?>> type) {
        final Object key = kryo.readClassAndObject( input );
        final Object value = kryo.readClassAndObject( input );
        return Collections.singletonMap( key, value );
    }

    @Override
    public void write(final Kryo kryo, final Output output, final Map<?, ?> map) {
        final Entry<?, ?> entry = map.entrySet().iterator().next();
        kryo.writeClassAndObject( output, entry.getKey() );
        kryo.writeClassAndObject( output, entry.getValue() );
    }


}