com.mchange.v2.util.CollectionUtils Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java v.0.2.3
*
* Copyright (C) 2012 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
package com.mchange.v2.util;
import java.util.*;
import java.lang.reflect.*;
/*
* Note: This class makes assumptions about the implementation of Collections.unmodifiableXXX( ... )
* and Collections.synchronizedXXX( ... ) that could conceivably not hold in some Java std class
* implementation... but the implementation is robust to the most likely implementations of these
* methods.
*/
public final class CollectionUtils
{
public final static SortedSet EMPTY_SORTED_SET = Collections.unmodifiableSortedSet( new TreeSet() );
final static Class[] EMPTY_ARG_CLASSES = { };
final static Object[] EMPTY_ARGS = { };
final static Class[] COMPARATOR_ARG_CLASSES = { Comparator.class };
final static Class[] COLLECTION_ARG_CLASSES = { Collection.class };
final static Class[] SORTED_SET_ARG_CLASSES = { SortedSet.class };
final static Class[] MAP_ARG_CLASSES = { Map.class };
final static Class[] SORTED_MAP_ARG_CLASSES = { SortedMap.class };
final static Class STD_UNMODIFIABLE_COLLECTION_CL;
final static Class STD_UNMODIFIABLE_SET_CL;
final static Class STD_UNMODIFIABLE_LIST_CL;
final static Class STD_UNMODIFIABLE_RA_LIST_CL;
final static Class STD_UNMODIFIABLE_SORTED_SET_CL;
final static Class STD_UNMODIFIABLE_MAP_CL;
final static Class STD_UNMODIFIABLE_SORTED_MAP_CL;
final static Class STD_SYNCHRONIZED_COLLECTION_CL;
final static Class STD_SYNCHRONIZED_SET_CL;
final static Class STD_SYNCHRONIZED_LIST_CL;
final static Class STD_SYNCHRONIZED_RA_LIST_CL;
final static Class STD_SYNCHRONIZED_SORTED_SET_CL;
final static Class STD_SYNCHRONIZED_MAP_CL;
final static Class STD_SYNCHRONIZED_SORTED_MAP_CL;
final static Set UNMODIFIABLE_WRAPPERS;
final static Set SYNCHRONIZED_WRAPPERS;
final static Set ALL_COLLECTIONS_WRAPPERS;
static
{
HashSet hs = new HashSet();
TreeSet ts = new TreeSet();
LinkedList ll = new LinkedList();
ArrayList al = new ArrayList();
HashMap hm = new HashMap();
TreeMap tm = new TreeMap();
HashSet tmp0 = new HashSet();
HashSet tmp1 = new HashSet();
tmp0.add( STD_UNMODIFIABLE_COLLECTION_CL = Collections.unmodifiableCollection( al ).getClass() );
tmp0.add( STD_UNMODIFIABLE_SET_CL = Collections.unmodifiableSet( hs ).getClass() );
tmp0.add( STD_UNMODIFIABLE_LIST_CL = Collections.unmodifiableList( ll ).getClass() );
tmp0.add( STD_UNMODIFIABLE_RA_LIST_CL = Collections.unmodifiableList( al ).getClass() );
tmp0.add( STD_UNMODIFIABLE_SORTED_SET_CL = Collections.unmodifiableSortedSet( ts ).getClass() );
tmp0.add( STD_UNMODIFIABLE_MAP_CL = Collections.unmodifiableMap( hm ).getClass() );
tmp0.add( STD_UNMODIFIABLE_SORTED_MAP_CL = Collections.unmodifiableSortedMap( tm ).getClass() );
tmp1.add( STD_SYNCHRONIZED_COLLECTION_CL = Collections.synchronizedCollection( al ).getClass() );
tmp1.add( STD_SYNCHRONIZED_SET_CL = Collections.synchronizedSet( hs ).getClass() );
tmp1.add( STD_SYNCHRONIZED_LIST_CL = Collections.synchronizedList( ll ).getClass() );
tmp1.add( STD_SYNCHRONIZED_RA_LIST_CL = Collections.synchronizedList( al ).getClass() );
tmp1.add( STD_SYNCHRONIZED_SORTED_SET_CL = Collections.synchronizedSortedSet( ts ).getClass() );
tmp1.add( STD_SYNCHRONIZED_MAP_CL = Collections.synchronizedMap( hm ).getClass() );
tmp1.add( STD_SYNCHRONIZED_SORTED_MAP_CL = Collections.synchronizedMap( tm ).getClass() );
UNMODIFIABLE_WRAPPERS = Collections.unmodifiableSet( tmp0 );
SYNCHRONIZED_WRAPPERS = Collections.unmodifiableSet( tmp1 );
HashSet tmp2 = new HashSet( tmp0 );
tmp2.addAll( tmp1 );
ALL_COLLECTIONS_WRAPPERS = Collections.unmodifiableSet( tmp2 );
}
public static boolean isCollectionsWrapper( Class cl )
{ return ALL_COLLECTIONS_WRAPPERS.contains( cl ); }
public static boolean isCollectionsWrapper( Collection c )
{ return isCollectionsWrapper( c.getClass() ); }
public static boolean isCollectionsWrapper( Map m )
{ return isCollectionsWrapper( m.getClass() ); }
public static boolean isSynchronizedWrapper( Class cl )
{ return SYNCHRONIZED_WRAPPERS.contains( cl ); }
public static boolean isSynchronizedWrapper( Collection c )
{ return isSynchronizedWrapper( c.getClass() ); }
public static boolean isSynchronizedWrapper( Map m )
{ return isSynchronizedWrapper( m.getClass() ); }
public static boolean isUnmodifiableWrapper( Class cl )
{ return UNMODIFIABLE_WRAPPERS.contains( cl ); }
public static boolean isUnmodifiableWrapper( Collection c )
{ return isUnmodifiableWrapper( c.getClass() ); }
public static boolean isUnmodifiableWrapper( Map m )
{ return isUnmodifiableWrapper( m.getClass() ); }
/*
* should we worry about the case where an Object (bizarrely)
* implements both Set and List? don't think so...
*/
public static Collection narrowUnmodifiableCollection( Collection c )
{
if (c instanceof SortedSet)
return Collections.unmodifiableSortedSet( (SortedSet) c );
else if (c instanceof Set)
return Collections.unmodifiableSet( (Set) c );
else if (c instanceof List)
return Collections.unmodifiableList( (List) c );
else
return Collections.unmodifiableCollection( c );
}
/*
* should we worry about the case where an Object (bizarrely)
* implements both Set and List? don't think so...
*/
public static Collection narrowSynchronizedCollection( Collection c )
{
if (c instanceof SortedSet)
return Collections.synchronizedSortedSet( (SortedSet) c );
else if (c instanceof Set)
return Collections.synchronizedSet( (Set) c );
else if (c instanceof List)
return Collections.synchronizedList( (List) c );
else
return Collections.synchronizedCollection( c );
}
public static Map narrowUnmodifiableMap( Map m )
{
if (m instanceof SortedMap)
return Collections.unmodifiableSortedMap( (SortedMap) m );
else
return Collections.unmodifiableMap( m );
}
public static Map narrowSynchronizedMap( Map m )
{
if (m instanceof SortedMap)
return Collections.synchronizedSortedMap( (SortedMap) m );
else
return Collections.synchronizedMap( m );
}
/**
* Attempts to find a public clone() method or a copy constructor, in that
* order, and calls what it finds. If neither is available, throws a NoSuchMethodException.
*/
public static Collection attemptClone( Collection c ) throws NoSuchMethodException
{
if (c instanceof Vector) return (Collection) ((Vector) c).clone();
else if (c instanceof ArrayList) return (Collection) ((ArrayList) c).clone();
else if (c instanceof LinkedList) return (Collection) ((LinkedList) c).clone();
else if (c instanceof HashSet) return (Collection) ((HashSet) c).clone();
else if (c instanceof TreeSet) return (Collection) ((TreeSet) c).clone();
else
{
Collection out = null;
Class colClass = c.getClass();
try
{
Method m = colClass.getMethod("clone", EMPTY_ARG_CLASSES);
out = (Collection) m.invoke( c, EMPTY_ARGS );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible clone() here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
if ( out == null )
{
try
{
Constructor ctor = colClass.getConstructor( (c instanceof SortedSet) ? SORTED_SET_ARG_CLASSES : COLLECTION_ARG_CLASSES );
out = (Collection) ctor.newInstance( new Object[] { c } );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible ctor here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
}
if ( out == null )
{
try
{
Constructor ctor = colClass.getConstructor( new Class[] { colClass } );
out = (Collection) ctor.newInstance( new Object[] { c } );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible ctor here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
}
if (out == null)
throw new NoSuchMethodException("No accessible clone() method or reasonable copy constructor could be called on Collection " + c);
else
return out;
}
}
/**
* Attempts to find a public clone() method or a copy constructor, in that
* order, and calls what it finds. If neither is available, throws a NoSuchMethodException.
*/
public static Map attemptClone( Map m ) throws NoSuchMethodException
{
if (m instanceof Properties) return (Map) ((Properties) m).clone();
else if (m instanceof Hashtable) return (Map) ((Hashtable) m).clone();
else if (m instanceof HashMap) return (Map) ((HashMap) m).clone();
else if (m instanceof TreeMap) return (Map) ((TreeMap) m).clone();
else
{
Map out = null;
Class mapClass = m.getClass();
try
{
Method meth = mapClass.getMethod("clone", EMPTY_ARG_CLASSES);
out = (Map) meth.invoke( m, EMPTY_ARGS );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible clone() here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
if ( out == null )
{
try
{
Constructor ctor = mapClass.getConstructor( (m instanceof SortedMap) ? SORTED_MAP_ARG_CLASSES : MAP_ARG_CLASSES );
out = (Map) ctor.newInstance( new Object[] { m } );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible ctor here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
}
if ( out == null )
{
try
{
Constructor ctor = mapClass.getConstructor( new Class[] { mapClass } );
out = (Map) ctor.newInstance( new Object[] { m } );
}
catch ( Exception e )
{
/* IGNORE... just means there's no accessible ctor here */
if ( Debug.DEBUG && Debug.TRACE == Debug.TRACE_MAX )
e.printStackTrace();
}
}
if (out == null)
throw new NoSuchMethodException("No accessible clone() method or reasonable copy constructor could be called on Map " + m);
else
return out;
}
}
/*
* These functions are primarily motivated by a desire
* to manipulate Collections from JSP 2.0 Expression
* Language functions, which must be mapped to public
* static functions.
*/
public static void add(Collection c, Object o)
{ c.add( o ); }
public static void remove(Collection c, Object o)
{ c.remove( o ); }
public static int size( Object o )
{
if (o instanceof Collection)
return ((Collection) o).size();
else if (o instanceof Map)
return ((Map) o).size();
else if (o instanceof Object[])
return ((Object[]) o).length;
else if (o instanceof boolean[])
return ((boolean[]) o).length;
else if (o instanceof byte[])
return ((byte[]) o).length;
else if (o instanceof char[])
return ((char[]) o).length;
else if (o instanceof short[])
return ((short[]) o).length;
else if (o instanceof int[])
return ((int[]) o).length;
else if (o instanceof long[])
return ((long[]) o).length;
else if (o instanceof float[])
return ((float[]) o).length;
else if (o instanceof double[])
return ((double[]) o).length;
else
throw new IllegalArgumentException(o + " must be a Collection, Map, or array!");
}
private CollectionUtils()
{}
}
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