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org.kuali.common.util.CollectionUtils Maven / Gradle / Ivy
/**
* Copyright 2010-2013 The Kuali Foundation
*
* Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
*
* 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.kuali.common.util;
import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.kuali.common.util.nullify.NullUtils;
import org.kuali.common.util.property.Constants;
public class CollectionUtils {
/**
* Get an unmodifiable list from the single element. Return emptyList() if element is null.
*/
public static List unmodifiableList(T element) {
List list = toEmptyList(element);
return Collections.unmodifiableList(list);
}
/**
* Get an unmodifiable list from the single element. Return emptyList() if element is null.
*/
public static List unmodifiableList(T... elements) {
return Collections.unmodifiableList(Arrays.asList(elements));
}
/**
* If the CSV value evaluates to null, "null", "none" or the empty string, return an empty list.
*/
public static List getNoneSensitiveListFromCSV(String csv) {
if (StringUtils.isBlank(csv) || NullUtils.isNullOrNone(csv)) {
return Collections. emptyList();
} else {
return CollectionUtils.getTrimmedListFromCSV(csv);
}
}
/**
* Remove any Strings from the list that do not match the filter and then sort the ones that remain
*/
public static List filterAndSort(List strings, StringFilter filter) {
List excluded = filter(strings, filter);
Collections.sort(strings);
return excluded;
}
/**
* Remove any Strings from the collection that do not match the filter
*/
public static List filter(Collection strings, StringFilter filter) {
List excluded = new ArrayList();
Iterator itr = strings.iterator();
while (itr.hasNext()) {
String string = itr.next();
if (!filter.include(string)) {
excluded.add(string);
itr.remove();
}
}
return excluded;
}
/**
* Null safe method for converting an array of objects into a list. Never returns null.
*/
public static List asList(Object... objects) {
List list = new ArrayList();
if (objects == null) {
return list;
}
for (Object element : objects) {
if (element != null) {
list.add(element);
}
}
return list;
}
/**
* Null safe method for converting an untyped array of classes into a list. Never returns null.
*/
public static List> asList(Class... classes) {
List> list = new ArrayList>();
if (classes == null) {
return list;
}
for (Class element : classes) {
if (element != null) {
list.add(element);
}
}
return list;
}
/**
* Return an array of int's that represents as even of a split as possible
*
* For example: passing in 100,7 returns 15, 15, 14, 14, 14, 14, 14
*
* @param numerator
* @param denominator
* @return
*/
public static int[] getDivideEvenly(int number, int howManyWays) {
Assert.isTrue(howManyWays > 0, "howManyWays must be a positive integer");
int quotient = number / howManyWays;
int remainder = number % howManyWays;
int[] lengths = new int[howManyWays];
for (int i = 0; i < howManyWays; i++) {
int length = i < remainder ? quotient + 1 : quotient;
lengths[i] = length;
}
return lengths;
}
/**
* Split elements evenly into separate lists divided up howManyWays
*/
public static final List> splitEvenly(List elements, int howManyWays) {
// Can't split 2 things 3 ways
if (howManyWays > elements.size()) {
howManyWays = elements.size();
}
int[] lengths = getDivideEvenly(elements.size(), howManyWays);
int offset = 0;
List> listOfLists = new ArrayList>();
for (int i = 0; i < lengths.length; i++) {
int length = lengths[i];
List sublist = new ArrayList();
for (int j = offset; j < offset + length; j++) {
sublist.add(elements.get(j));
}
listOfLists.add(sublist);
offset += length;
}
return listOfLists;
}
/**
* Prefix the strings passed in with their position in the list (left padded with zero's). The padding is the number of digits in the size of the list. A list with 100 elements
* will return strings prefixed with 000, 001, etc.
*/
public static final List getSequencedStrings(List strings, int initialSequenceNumber) {
List sequencedStrings = new ArrayList();
int size = strings.size();
int length = new Integer(size).toString().length();
String prefix = StringUtils.repeat("0", length);
for (String string : strings) {
String sequence = StringUtils.right(prefix + (initialSequenceNumber++), length);
String sequencedString = sequence + "-" + string;
sequencedStrings.add(sequencedString);
}
return sequencedStrings;
}
/**
* Prefix the strings passed in with their position in the list (left padded with zero's). The padding is the number of digits in the size of the list. A list with 100 elements
* will return strings prefixed with 000, 001, etc.
*/
public static final List getSequencedStrings(List strings) {
return getSequencedStrings(strings, 0);
}
/**
* Return a new List containing the unique set of strings from strings
*/
public static final List getUniqueStrings(List strings) {
List unique = new ArrayList();
for (String string : strings) {
if (!unique.contains(string)) {
unique.add(string);
}
}
return unique;
}
public static final List getUniqueFiles(List files) {
List strings = new ArrayList();
for (File file : files) {
strings.add(LocationUtils.getCanonicalPath(file));
}
List uniqueStrings = getUniqueStrings(strings);
List uniqueFiles = new ArrayList();
for (String uniqueString : uniqueStrings) {
uniqueFiles.add(new File(uniqueString));
}
return uniqueFiles;
}
public static final List getLines(String s) {
if (s == null) {
return Collections. emptyList();
}
try {
return IOUtils.readLines(new StringReader(s));
} catch (IOException e) {
throw new IllegalStateException(e);
}
}
/**
* Return a new list containing the unique set of strings contained in both lists
*/
public static final List combineStringsUniquely(List list1, List list2) {
List newList = getUniqueStrings(list1);
for (String element : list2) {
if (!newList.contains(element)) {
newList.add(element);
}
}
return newList;
}
protected static final T getNewInstance(Class c) {
try {
return c.newInstance();
} catch (IllegalAccessException e) {
throw new IllegalArgumentException(e);
} catch (InstantiationException e) {
throw new IllegalArgumentException(e);
}
}
/**
* Create a new list containing new instances of c
*/
public static final List getNewList(Class c, int size) {
List list = new ArrayList();
for (int i = 0; i < size; i++) {
T element = getNewInstance(c);
list.add(element);
}
return list;
}
/**
* Return a list containing only the elements where the corresponding index in the includes list is true. includes and list
* must be the same size.
*/
public static final List getList(List includes, List list) {
Assert.isTrue(includes.size() == list.size());
List included = new ArrayList();
for (int i = 0; i < includes.size(); i++) {
if (includes.get(i)) {
included.add(list.get(i));
}
}
return included;
}
/**
* Combine the list of lists into a single list
*/
public static final List combineLists(List> listOfLists) {
List combined = new ArrayList();
for (List list : listOfLists) {
combined.addAll(list);
}
return combined;
}
/**
* Combine the list of maps into a single map
*/
public static final Map combineMaps(List> listOfMaps) {
Map combined = new HashMap();
for (Map map : listOfMaps) {
combined.putAll(map);
}
return combined;
}
/**
* Return a combined list where required is always the first element in the list
*/
public static final List combine(T element, List list) {
Assert.notNull(element, "element is required");
if (list == null) {
return Collections.singletonList(element);
} else {
List combined = new ArrayList();
// Always insert required as the first element in the list
combined.add(element);
// Add the other elements
for (T optional : list) {
combined.add(optional);
}
return combined;
}
}
/**
* If o==null return an empty list otherwise return a singleton list.
*/
public static final List toEmptyList(T o) {
if (o == null) {
return Collections. emptyList();
} else {
return Collections.singletonList(o);
}
}
/**
* If list==null return an empty list otherwise return list
*/
public static final List toEmptyList(List list) {
if (list == null) {
return Collections. emptyList();
} else {
return list;
}
}
public static final List toNullIfEmpty(List list) {
if (isEmpty(list)) {
return null;
} else {
return list;
}
}
public static final Collection toNullIfEmpty(Collection c) {
if (isEmpty(c)) {
return null;
} else {
return c;
}
}
public static final List getPreFilledList(int size, T value) {
if (value == null || size < 1) {
return Collections. emptyList();
} else {
List list = new ArrayList(size);
for (int i = 0; i < size; i++) {
list.add(value);
}
return list;
}
}
public static final String getSpaceSeparatedCSV(List strings) {
return getStringWithSeparator(strings, ", ");
}
public static final String getStringWithSeparator(List list, String separator) {
list = toEmptyList(list);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < toEmptyList(list).size(); i++) {
if (i != 0) {
sb.append(separator);
}
Object element = list.get(i);
if (element != null) {
sb.append(element.toString());
} else {
sb.append(Constants.NULL);
}
}
return sb.toString();
}
public static final String getCSV(List strings) {
return getStringWithSeparator(strings, ",");
}
public static final String getSpaceSeparatedString(List list) {
return getStringWithSeparator(list, " ");
}
public static final Object[] toObjectArray(List objects) {
return objects.toArray(new Object[objects.size()]);
}
public static final String[] toStringArray(List strings) {
return strings.toArray(new String[strings.size()]);
}
public static final boolean isEmpty(Collection c) {
return c == null || c.size() == 0;
}
public static final List sortedMerge(List list, String csv) {
Set set = new TreeSet();
set.addAll(toEmptyList(list));
set.addAll(getTrimmedListFromCSV(csv));
return new ArrayList(set);
}
public static final List getTrimmedListFromCSV(String csv) {
if (StringUtils.isBlank(csv)) {
return Collections. emptyList();
}
List list = new ArrayList();
String[] tokens = Str.splitAndTrimCSV(csv);
list.addAll(Arrays.asList(tokens));
return list;
}
public static final List nullSafeCombine(List list1, List list2) {
List combined = new ArrayList();
if (!isEmpty(list1)) {
combined.addAll(list1);
}
if (!isEmpty(list2)) {
combined.addAll(list2);
}
return combined;
}
public static final List combineStrings(List list1, List list2, List list3) {
List combined = new ArrayList();
nullSafeAdd(combined, list1);
nullSafeAdd(combined, list2);
nullSafeAdd(combined, list3);
return combined;
}
/**
* Return a new list containing all of the strings from both lists with string added in between the strings from both lists
*/
public static final List combineStrings(List list1, String string, List list2) {
return combineStrings(list1, toEmptyList(string), list2);
}
/**
* Return a new list containing all of the strings from both lists
*/
public static final List combineStrings(List list1, List list2) {
return combineStrings(list1, (String) null, list2);
}
/**
* Return a new list containing all of the elements from the lists passed in
*/
public static final List combine(List list1, List list2) {
return combine(list1, list2, null);
}
public static final List combine(List list1, List list2, List list3) {
List combined = new ArrayList();
combined.addAll(toEmptyList(list1));
combined.addAll(toEmptyList(list2));
combined.addAll(toEmptyList(list3));
return combined;
}
public static final void nullSafeAdd(List list1, List list2) {
if (list2 != null) {
list1.addAll(list2);
}
}
/**
* Return true if s contains any of the strings from strings
*/
public static final boolean containsAny(String s, List strings) {
for (String string : strings) {
if (StringUtils.contains(s, string)) {
return true;
}
}
return false;
}
}
