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Groovy example source code file (SpreadMap.java)

This example Groovy source code file (SpreadMap.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

hashmap, iterator, iterator, map, object, object, runtimeexception, runtimeexception, spreadmap, spreadmap, string, stringbuffer, util

The Groovy SpreadMap.java source code

/*
 * Copyright 2003-2011 the original author or authors.
 *
 * 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 groovy.lang;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Iterator;

import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;

/**
 * Represents a spreadable map which extends java.util.HashMap.
 * 
 * @author Pilho Kim
 */
public class SpreadMap extends HashMap {

    private Map mapData;
    private int hashCode;

    public SpreadMap(Object[] values) {
        mapData = new HashMap(values.length / 2);
        int i = 0;
        while (i < values.length) {
           mapData.put(values[i++], values[i++]);
        }
    }

    public SpreadMap(Map map) {
        this.mapData = map;
    }

    /**
     * @since 1.8.0
     * @param list the list to make spreadable
     */
    public SpreadMap(List list) {
        this(list.toArray());
    }

    public Object get(Object obj) {
        return mapData.get(obj);
    }

    public Object put(Object key, Object value) {
        throw new RuntimeException("SpreadMap: " + this + " is an immutable map, and so ("
                                   + key + ": " + value + ") cannot be added.");
    }

    public Object remove(Object key) {
        throw new RuntimeException("SpreadMap: " + this + " is an immutable map, and so the key ("
                                   + key + ") cannot be deleted.");
    }

    public void putAll(Map t) {
        throw new RuntimeException("SpreadMap: " + this + " is an immutable map, and so the map ("
                                   + t + ") cannot be put in this spreadMap.");
    }

    public int size() {
        return mapData.keySet().size();
    }

    public boolean equals(Object that) {
        if (that instanceof SpreadMap) {
            return equals((SpreadMap) that);
        }
        return false;
    }

    public boolean equals(SpreadMap that) {
        if (that == null) return false;        

        if (size() == that.size()) {
            Iterator iter = mapData.keySet().iterator();
            for (; iter.hasNext(); ) {
                Object key = iter.next();
                if (! DefaultTypeTransformation.compareEqual(get(key), that.get(key)) ) {
                    return false;
                }
            }
            return true;
        }
        return false;
    }


    public int hashCode() {
        if (hashCode == 0) {
            Iterator iter = mapData.keySet().iterator();
            for (; iter.hasNext(); ) {
                Object key = iter.next();
                int hash = (key != null) ? key.hashCode() : 0xbabe;
                hashCode ^= hash;
            }
        }
        return hashCode;
    }

    /**
     * @return the string expression of <code>this
     */
    public String toString() {
        if (mapData.isEmpty()) {
            return "*:[:]";
        }
        StringBuffer buff = new StringBuffer("*:[");
        Iterator iter = mapData.keySet().iterator();
        for (; iter.hasNext(); ) {
            Object key = iter.next();
            buff.append(key + ":" + mapData.get(key));
            if (iter.hasNext())
                buff.append(", ");
        }
        buff.append("]");
        return buff.toString();
    }
}

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