org.metawidget.util.CollectionUtils Maven / Gradle / Ivy
// Metawidget
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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 library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package org.metawidget.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import java.util.TreeMap;
import java.util.WeakHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.metawidget.util.simple.StringUtils;
/**
* Utilities for working with Java Collections.
*
* @author Richard Kennard
*/
public final class CollectionUtils {
//
// Public statics
//
/**
* Type-safe initializer.
*/
public static final ArrayList newArrayList() {
return new ArrayList();
}
/**
* Type-safe initializer.
*/
public static final ArrayList newArrayList( Collection collection ) {
return new ArrayList( collection );
}
/**
* Type-safe initializer.
*/
public static final ArrayList newArrayList( int capacity ) {
return new ArrayList( capacity );
}
/**
* Type-safe initializer.
*/
public static final ArrayList newArrayList( T... array ) {
if ( array == null ) {
return new ArrayList();
}
return new ArrayList( Arrays.asList( array ) );
}
/**
* Type-safe initializer.
*/
public static final HashSet newHashSet() {
return new HashSet();
}
/**
* Type-safe initializer.
*/
public static final HashSet newHashSet( Collection set ) {
return new HashSet( set );
}
/**
* Type-safe initializer.
*/
public static final HashSet newHashSet( K... array ) {
return new HashSet( Arrays.asList( array ) );
}
/**
* Type-safe initializer.
*/
public static final Stack newStack() {
return new Stack();
}
/**
* Type-safe initializer.
*/
public static final HashMap newHashMap() {
return new HashMap();
}
/**
* Type-safe initializer.
*/
public static final HashMap newHashMap( Map map ) {
return new HashMap( map );
}
/**
* Type-safe initializer.
*/
public static final HashMap newHashMap( int size ) {
return new HashMap( size );
}
/**
* Type-safe initializer.
*
* WeakHashMap is preferrable if K is of type Class.
*/
public static final WeakHashMap newWeakHashMap() {
return new WeakHashMap();
}
/**
* Type-safe initializer.
*/
public static final LinkedHashMap newLinkedHashMap() {
return new LinkedHashMap();
}
/**
* Type-safe initializer.
*/
public static final LinkedHashMap newLinkedHashMap( Map map ) {
return new LinkedHashMap( map );
}
/**
* Type-safe initializer.
*/
public static final TreeMap newTreeMap() {
return new TreeMap();
}
public static List unmodifiableList( T... array ) {
return Collections.unmodifiableList( Arrays.asList( array ) );
}
public static String toString( Collection collection ) {
return toString( collection, StringUtils.SEPARATOR_COMMA );
}
public static String toString( Collection collection, String separator ) {
return toString( collection, separator, false, false );
}
public static String toString( Collection collection, String separator, boolean leadingSeparator, boolean trailingSeparator ) {
// Nothing to do?
if ( collection == null ) {
return "";
}
// If Collection is a Set, sort it for consistency in unit tests. Never
// sort the original Collection, as users wouldn't expect toString() to do that!
Collection consistentlyOrderedCollection = collection;
if ( consistentlyOrderedCollection instanceof Set ) {
consistentlyOrderedCollection = newArrayList( collection );
Collections.sort( (List) consistentlyOrderedCollection, null );
}
// Output as a String
Pattern patternSeparator = Pattern.compile( separator, Pattern.LITERAL );
String replacement = "\\\\" + separator;
// (use StringBuffer for J2SE 1.4 compatibility)
StringBuffer buffer = new StringBuffer();
for ( T t : consistentlyOrderedCollection ) {
String value = String.valueOf( t );
// Concatenate the separator
if ( buffer.length() > 0 || leadingSeparator ) {
buffer.append( separator );
}
// Escape the separator
value = patternSeparator.matcher( value ).replaceAll( replacement );
// Build the string
buffer.append( value );
}
if ( trailingSeparator && buffer.length() > 0 ) {
buffer.append( separator );
}
return buffer.toString();
}
/**
* Split the given String by comma. Commas within Strings may be escaped using the backslash (\)
* character. Starting and ending whitespace around each String will be trimmed.
*/
public static List fromString( final String collection ) {
return fromString( collection, ',' );
}
/**
* Split the given String by the given separator. Separators within Strings may be escaped using
* the backslash (\) character. Starting and ending whitespace around each sub-String will be
* trimmed.
*/
public static List fromString( final String collection, char separator ) {
if ( collection == null || collection.length() == 0 ) {
// (use Collections.EMPTY_LIST, not Collections.emptyList, so that we're 1.4 compatible)
@SuppressWarnings( "unchecked" )
List list = Collections.EMPTY_LIST;
return list;
}
List split = CollectionUtils.newArrayList();
Pattern patternSplit = Pattern.compile( "((\\\\" + separator + "|[^" + separator + "])*)(" + separator + "|$)" );
Pattern patternSeparator = Pattern.compile( "\\" + separator, Pattern.LITERAL );
String replacement = String.valueOf( separator );
Matcher matcher = patternSplit.matcher( collection );
while ( matcher.find() ) {
String match = matcher.group( 1 ).trim();
match = patternSeparator.matcher( match ).replaceAll( replacement );
split.add( match );
if ( matcher.end( 1 ) == collection.length() ) {
break;
}
}
return split;
}
//
// Private constructor
//
private CollectionUtils() {
// Can never be called
}
}