org.mule.util.CollectionUtils Maven / Gradle / Ivy
/*
* $Id: CollectionUtils.java 19191 2010-08-25 21:05:23Z tcarlson $
* --------------------------------------------------------------------------------------
* Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com
*
* The software in this package is published under the terms of the CPAL v1.0
* license, a copy of which has been included with this distribution in the
* LICENSE.txt file.
*/
package org.mule.util;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import org.apache.commons.collections.Predicate;
// @ThreadSafe
public class CollectionUtils extends org.apache.commons.collections.CollectionUtils
{
/**
* Creates an array of the given Collection's elements, but with the given
* Class as element type. Useful for arrays of objects that
* implement multiple interfaces and a "typed view" onto these objects is
* required.
*
* @param objects a Collection of objects
* @param clazz the desired service type of the new array
* @return null when objects is null, or a new
* array containing the elements of the source array which is typed to
* the given clazz parameter.
* @throws IllegalArgumentException if the clazz argument is
* null.
* @throws ArrayStoreException if the elements in objects cannot
* be cast to clazz.
*/
public static T[] toArrayOfComponentType(Collection objects, Class clazz)
{
if (objects == null)
{
return null;
}
if (clazz == null)
{
throw new IllegalArgumentException("Array target class must not be null");
}
if (objects.isEmpty())
{
return (T[]) Array.newInstance(clazz, 0);
}
int i = 0, size = objects.size();
T[] result = (T[]) Array.newInstance(clazz, size);
Iterator iter = objects.iterator();
while (i < size && iter.hasNext())
{
result[i++] = (T)iter.next();
}
return result;
}
/**
* Creates a String representation of the given Collection, with optional
* newlines between elements. Class objects are represented by their full names.
*
* @param c the Collection to format
* @param newline indicates whether elements are to be split across lines
* @return the formatted String
*/
public static String toString(Collection c, boolean newline)
{
if (c == null || c.isEmpty())
{
return "[]";
}
return toString(c, c.size(), newline);
}
/**
* Calls {@link #toString(Collection, int, boolean)} with false
* for newline.
*/
public static String toString(Collection c, int maxElements)
{
return toString(c, maxElements, false);
}
/**
* Creates a String representation of the given Collection, with optional
* newlines between elements. Class objects are represented by their full names.
* Considers at most maxElements values; overflow is indicated by
* an appended "[..]" ellipsis.
*
* @param c the Collection to format
* @param maxElements the maximum number of elements to take into account
* @param newline indicates whether elements are to be split across lines
* @return the formatted String
*/
public static String toString(Collection c, int maxElements, boolean newline)
{
if (c == null || c.isEmpty())
{
return "[]";
}
int origNumElements = c.size();
int numElements = Math.min(origNumElements, maxElements);
boolean tooManyElements = (origNumElements > maxElements);
StringBuffer buf = new StringBuffer(numElements * 32);
buf.append('[');
if (newline)
{
buf.append(SystemUtils.LINE_SEPARATOR);
}
Iterator items = c.iterator();
for (int i = 0; i < numElements - 1; i++)
{
Object item = items.next();
if (item instanceof Class)
{
buf.append(((Class) item).getName());
}
else
{
buf.append(item);
}
if (newline)
{
buf.append(SystemUtils.LINE_SEPARATOR);
}
else
{
buf.append(',').append(' ');
}
}
// don't forget the last one
Object lastItem = items.next();
if (lastItem instanceof Class)
{
buf.append(((Class) lastItem).getName());
}
else
{
buf.append(lastItem);
}
if (newline)
{
buf.append(SystemUtils.LINE_SEPARATOR);
}
if (tooManyElements)
{
buf.append(" [..]");
}
buf.append(']');
return buf.toString();
}
/**
* Some code uses null to indicate "unset", which makes appending items complex.
*/
public static List addCreate(List list, Object value)
{
if (null == list)
{
return singletonList(value);
}
else
{
list.add(value);
return list;
}
}
public static List singletonList(Object value)
{
List list = new LinkedList();
list.add(value);
return list;
}
public static boolean containsType(Collection collection, final Class type)
{
if (type == null)
{
return false;
}
return exists(collection, new Predicate()
{
public boolean evaluate(Object object)
{
return object != null && type.isAssignableFrom(object.getClass());
}
});
}
public static void removeType(Collection collection, final Class type)
{
if (type == null)
{
return;
}
filter(collection, new Predicate()
{
public boolean evaluate(Object object)
{
return object != null && type.isAssignableFrom(object.getClass());
}
});
}
}