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Groovy example source code file (ListHashMap.java)

This example Groovy source code file (ListHashMap.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

arraylist, collection, entry, hashmap, k, listhashmap, listhashmap, map, map, object, object, set, util, v, v

The Groovy ListHashMap.java source code

/*
 * Copyright 2003-2010 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 org.codehaus.groovy.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * This represents a 
 * @author <a href="mailto:blackdrag@gmx.org">Jochen "blackdrag" Theodorou
 */
public class ListHashMap<K,V> implements Map {
    private int listFill = 0;
    private Object[] listKeys;
    private Object[] listValues;
    private int size = 0;
    private Map<K,V> innerMap;
    private final int maxListFill;
    
    public ListHashMap() {
        this(3);
    }
    
    public ListHashMap(int listSize){
        this.listKeys = new Object[listSize];
        this.listValues = new Object[listSize];
        maxListFill = listSize;
    }
    
    public void clear() {
        listFill = 0;
        innerMap = null;
        for (int i=0; i<maxListFill; i++) {
            listValues[i] = null;
            listKeys[i] = null;
        }
    }

    public boolean containsKey(Object key) {
        if (size<maxListFill) {
            for (int i=0; i<listFill; i++) {
                if (listKeys[i].equals(key)) return true;
            }
            return false;
        } else {
            return innerMap.containsKey(key);
        }
    }

    public boolean containsValue(Object value) {
        if (size<maxListFill) {
            for (int i=0; i<listFill; i++) {
                if (listValues[i].equals(value)) return true;
            }
            return false;
        } else {
            return innerMap.containsValue(value);
        }
    }

    private Map<K,V> makeMap() {
        Map<K,V> m = new HashMap();
        for (int i=0; i<size; i++) {
            m.put((K) listKeys[i], (V) listValues[i]);
        }
        return m;
    }
    
    public Set<java.util.Map.Entry entrySet() {
        Map m;
        if (size>maxListFill) {
            m = innerMap;
        } else {
            m = makeMap();
        }
        return m.entrySet();
    }

    public V get(Object key) {
        if(size==0) return null;
        if (size<maxListFill) {
            for (int i=0; i<maxListFill; i++) {
                if (listKeys[i].equals(key)) return (V) listValues[i];
            }
            return null;
        } else {
            return innerMap.get(key);
        }
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public Set<K> keySet() {
        Map m;
        if (size>=maxListFill) {
            m = innerMap;
        } else {
            m = makeMap();
        }
        return m.keySet();
    }

    public V put(K key, V value) {
        if (size<maxListFill) {
            for (int i=0; i<listFill; i++) {
                if (listKeys[i].equals(key)) {
                    V old = (V) listValues[i];
                    listValues[i] = value;
                    return old;
                } 
            }
            if (size<maxListFill-1) {
                size++;
                listKeys[listFill] = key;
                listValues[listFill] = value;
                listFill++;
                return null;
            } else {
                innerMap = makeMap();
            }
        } 
        return innerMap.put(key,value);
    }

    public void putAll(Map<? extends K, ? extends V> m) {
       if (size+m.size()<maxListFill) {
           for (Entry<? extends K,? extends V> entry : m.entrySet()) {
               listKeys[listFill] = entry.getKey();
               listValues[listFill] = entry.getValue();
               listFill++;
           }
           size += m.size();
           return;
       } 
       if (size<maxListFill) innerMap = makeMap();
       innerMap.putAll(m);
       size += m.size();
    }

    public V remove(Object key) {
        if (size<maxListFill) {
            for (int i=0; i<listFill; i++) {
                if (listKeys[i].equals(key)) {
                    V old = (V) listValues[i];
                    listFill--; size--;
                    listValues[i] = listValues[listFill];
                    listKeys[i] = listValues[listFill];
                    return old;
                }
            }
            return null;
        } else {
            V old = innerMap.remove(key);
            if (old!=null) size--;
            if (size<maxListFill) {
                mapToList();
            }
            return old;
        }
    }
    
    private void mapToList() {
        int i = 0;
        for (Entry<? extends K,? extends V> entry : innerMap.entrySet()) {
            listKeys[i] = entry.getKey();
            listValues[i] = entry.getValue();
            i++;
        }
        listFill = innerMap.size();
        innerMap = null;
    }

    public int size() {
        return size;
    }

    public Collection<V> values() {
        if (size<maxListFill) {
            ArrayList<V> list = new ArrayList(size);
            for (int i=0; i<listFill; i++) {
                list.add((V) listValues[i]);
            }
            return list;
        } else {
            return innerMap.values();
        }
    }
    
}

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