maputils.java

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/*
 *  Copyright 2001-2005 The Apache Software Foundation
 *
 *  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.collections;

import java.io.PrintStream;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.SortedMap;
import java.util.TreeMap;

import org.apache.commons.collections.map.FixedSizeMap;
import org.apache.commons.collections.map.FixedSizeSortedMap;
import org.apache.commons.collections.map.LazyMap;
import org.apache.commons.collections.map.LazySortedMap;
import org.apache.commons.collections.map.ListOrderedMap;
import org.apache.commons.collections.map.MultiValueMap;
import org.apache.commons.collections.map.PredicatedMap;
import org.apache.commons.collections.map.PredicatedSortedMap;
import org.apache.commons.collections.map.TransformedMap;
import org.apache.commons.collections.map.TransformedSortedMap;
import org.apache.commons.collections.map.TypedMap;
import org.apache.commons.collections.map.TypedSortedMap;
import org.apache.commons.collections.map.UnmodifiableMap;
import org.apache.commons.collections.map.UnmodifiableSortedMap;

/** 
 * Provides utility methods and decorators for
 * {@link Map} and {@link SortedMap} instances.
 * <p>
 * It contains various type safe methods
 * as well as other useful features like deep copying.
 * <p>
 * It also provides the following decorators:
 *
 *  <ul>
 *  <li>{@link #fixedSizeMap(Map)}
 *  <li>{@link #fixedSizeSortedMap(SortedMap)}
 *  <li>{@link #lazyMap(Map,Factory)}
 *  <li>{@link #lazyMap(Map,Transformer)}
 *  <li>{@link #lazySortedMap(SortedMap,Factory)}
 *  <li>{@link #lazySortedMap(SortedMap,Transformer)}
 *  <li>{@link #predicatedMap(Map,Predicate,Predicate)}
 *  <li>{@link #predicatedSortedMap(SortedMap,Predicate,Predicate)}
 *  <li>{@link #transformedMap(Map, Transformer, Transformer)}
 *  <li>{@link #transformedSortedMap(SortedMap, Transformer, Transformer)}
 *  <li>{@link #typedMap(Map, Class, Class)}
 *  <li>{@link #typedSortedMap(SortedMap, Class, Class)}
 *  <li>{@link #multiValueMap( Map )}
 *  <li>{@link #multiValueMap( Map, Class )}
 *  <li>{@link #multiValueMap( Map, Factory )}
 *  </ul>
 *
 * @since Commons Collections 1.0
 * @version $Revision: 357494 $ $Date: 2005-12-18 19:05:31 +0000 (Sun, 18 Dec 2005) $
 * 
 * @author <a href="mailto:[e-mail]">James Strachan</a>
 * @author <a href="mailto:[e-mail]">Nissim Karpenstein</a>
 * @author <a href="mailto:[e-mail]">Kasper Nielsen</a>
 * @author Paul Jack
 * @author Stephen Colebourne
 * @author Matthew Hawthorne
 * @author Arun Mammen Thomas
 * @author Janek Bogucki
 * @author Max Rydahl Andersen
 * @author <a href="mailto:[e-mail]">Ashwin S</a>
 * @author <a href="mailto:[e-mail]">James Carman</a>
 * @author Neil O'Toole
 */
public class MapUtils {
    
    /**
     * An empty unmodifiable map.
     * This was not provided in JDK1.2.
     */
    public static final Map EMPTY_MAP = UnmodifiableMap.decorate(new HashMap(1));
    /**
     * An empty unmodifiable sorted map.
     * This is not provided in the JDK.
     */
    public static final SortedMap EMPTY_SORTED_MAP = UnmodifiableSortedMap.decorate(new TreeMap());
    /**
     * String used to indent the verbose and debug Map prints.
     */
    private static final String INDENT_STRING = "    ";

    /**
     * <code>MapUtils</code> should not normally be instantiated.
     */
    public MapUtils() {
    }    
    
    // Type safe getters
    //-------------------------------------------------------------------------
    /**
     * Gets from a Map in a null-safe manner.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map, <code>null</code> if null map input
     */
    public static Object getObject(final Map map, final Object key) {
        if (map != null) {
            return map.get(key);
        }
        return null;
    }

    /**
     * Gets a String from a Map in a null-safe manner.
     * <p>
     * The String is obtained via <code>toString</code>.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a String, <code>null</code> if null map input
     */
    public static String getString(final Map map, final Object key) {
        if (map != null) {
            Object answer = map.get(key);
            if (answer != null) {
                return answer.toString();
            }
        }
        return null;
    }

    /**
     * Gets a Boolean from a Map in a null-safe manner.
     * <p>
     * If the value is a <code>Boolean</code> it is returned directly.
     * If the value is a <code>String</code> and it equals 'true' ignoring case
     * then <code>true</code> is returned, otherwise <code>false</code>.
     * If the value is a <code>Number</code> an integer zero value returns
     * <code>false</code> and non-zero returns <code>true</code>.
     * Otherwise, <code>null</code> is returned.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Boolean, <code>null</code> if null map input
     */
    public static Boolean getBoolean(final Map map, final Object key) {
        if (map != null) {
            Object answer = map.get(key);
            if (answer != null) {
                if (answer instanceof Boolean) {
                    return (Boolean) answer;
                    
                } else if (answer instanceof String) {
                    return new Boolean((String) answer);
                    
                } else if (answer instanceof Number) {
                    Number n = (Number) answer;
                    return (n.intValue() != 0) ? Boolean.TRUE : Boolean.FALSE;
                }
            }
        }
        return null;
    }

    /**
     * Gets a Number from a Map in a null-safe manner.
     * <p>
     * If the value is a <code>Number</code> it is returned directly.
     * If the value is a <code>String</code> it is converted using
     * {@link NumberFormat#parse(String)} on the system default formatter
     * returning <code>null</code> if the conversion fails.
     * Otherwise, <code>null</code> is returned.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Number, <code>null</code> if null map input
     */
    public static Number getNumber(final Map map, final Object key) {
        if (map != null) {
            Object answer = map.get(key);
            if (answer != null) {
                if (answer instanceof Number) {
                    return (Number) answer;
                    
                } else if (answer instanceof String) {
                    try {
                        String text = (String) answer;
                        return NumberFormat.getInstance().parse(text);
                        
                    } catch (ParseException e) {
                        logInfo(e);
                    }
                }
            }
        }
        return null;
    }

    /**
     * Gets a Byte from a Map in a null-safe manner.
     * <p>
     * The Byte is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Byte, <code>null</code> if null map input
     */
    public static Byte getByte(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Byte) {
            return (Byte) answer;
        }
        return new Byte(answer.byteValue());
    }

    /**
     * Gets a Short from a Map in a null-safe manner.
     * <p>
     * The Short is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Short, <code>null</code> if null map input
     */
    public static Short getShort(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Short) {
            return (Short) answer;
        }
        return new Short(answer.shortValue());
    }

    /**
     * Gets a Integer from a Map in a null-safe manner.
     * <p>
     * The Integer is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Integer, <code>null</code> if null map input
     */
    public static Integer getInteger(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Integer) {
            return (Integer) answer;
        }
        return new Integer(answer.intValue());
    }

    /**
     * Gets a Long from a Map in a null-safe manner.
     * <p>
     * The Long is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Long, <code>null</code> if null map input
     */
    public static Long getLong(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Long) {
            return (Long) answer;
        }
        return new Long(answer.longValue());
    }

    /**
     * Gets a Float from a Map in a null-safe manner.
     * <p>
     * The Float is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Float, <code>null</code> if null map input
     */
    public static Float getFloat(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Float) {
            return (Float) answer;
        }
        return new Float(answer.floatValue());
    }

    /**
     * Gets a Double from a Map in a null-safe manner.
     * <p>
     * The Double is obtained from the results of {@link #getNumber(Map,Object)}.
     *
     * @param map  the map to use
     * @param key  the key to look up
     * @return the value in the Map as a Double, <code>null</code> if null map input
     */
    public static Double getDouble(final Map map, final Object key) {
        Number answer = getNumber(map, key);
        if (answer == null) {
            return null;
        } else if (answer instanceof Double) {
            return (Double) answer;
        }
        return new Double(answer.doubleValue());
    }

    /**
     * Gets a Map from a Map in a null-safe manner.