com.groupbyinc.common.util.JavaUtils Maven / Gradle / Ivy
package com.groupbyinc.common.util;
import com.groupbyinc.common.util.exception.GroupByUtilException;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Java utilities
*
* @author Alan Czajkowski
*/
public final class JavaUtils {
private JavaUtils() {
// not publicly instantiable
}
/**
* Return a non-null {@link List}.
*
* @param list
* a list (can be null)
*
* @return {@link List} a non-null immutable list
*/
public static List notNull(List list) {
return list == null ? Collections.emptyList() : list;
}
/**
* Return a non-null {@link Set}.
*
* @param set
* a set (can be null)
*
* @return {@link Set} a non-null immutable set
*/
public static Set notNull(Set set) {
return set == null ? Collections.emptySet() : set;
}
/**
* Return a non-null {@link Collection}.
*
* @param collection
* a collection (List or Set, can be null)
*
* @return {@link Collection} a non-null immutable collection
*/
public static Collection notNull(Collection collection) {
if (collection instanceof List) {
return notNull((List) collection);
} else if (collection instanceof Set) {
return notNull((Set) collection);
}
throw new GroupByUtilException("Not a List or Set");
}
/**
* Return a non-null {@link Map}.
*
* @param map
* a map (can be null)
*
* @return {@link Map} a non-null immutable map
*/
public static Map notNull(Map map) {
return map == null ? Collections.emptyMap() : map;
}
}