ObjectUtils.java
/*
* Portions of this software was developed by employees of the National Institute
* of Standards and Technology (NIST), an agency of the Federal Government and is
* being made available as a public service. Pursuant to title 17 United States
* Code Section 105, works of NIST employees are not subject to copyright
* protection in the United States. This software may be subject to foreign
* copyright. Permission in the United States and in foreign countries, to the
* extent that NIST may hold copyright, to use, copy, modify, create derivative
* works, and distribute this software and its documentation without fee is hereby
* granted on a non-exclusive basis, provided that this notice and disclaimer
* of warranty appears in all copies.
*
* THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
* EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
* THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
* INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
* SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
* SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
* INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
* OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
* CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
* PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
* OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
*/
package gov.nist.secauto.metaschema.core.util;
import java.util.Objects;
import java.util.stream.Stream;
import edu.umd.cs.findbugs.annotations.NonNull;
public final class ObjectUtils {
private ObjectUtils() {
// disable construction
}
/**
* Assert that the provided object is not {@code null}.
* <p>
* This method sets the expectation that the provided object is not {@code null}
* in cases where a non-null value is required.
*
* @param <T>
* the object type
* @param obj
* the object
* @return the object
*/
@NonNull
public static <T> T notNull(T obj) {
assert obj != null;
return obj;
}
/**
* Require a non-null value.
*
* @param <T>
* the type of the reference
* @param obj
* the object reference to check for nullity
* @return {@code obj} if not {@code null}
* @throws NullPointerException
* if {@code obj} is {@code null}
*/
@NonNull
public static <T> T requireNonNull(T obj) {
if (obj == null) {
throw new NullPointerException(); // NOPMD
}
return obj;
}
/**
* Require a non-null value.
*
* @param <T>
* the type of the reference
* @param obj
* the object reference to check for nullity
* @param message
* detail message to be used in the event that a {@code
* NullPointerException} is thrown
* @return {@code obj} if not {@code null}
* @throws NullPointerException
* if {@code obj} is {@code null}
*/
@NonNull
public static <T> T requireNonNull(T obj, @NonNull String message) {
if (obj == null) {
throw new NullPointerException(message); // NOPMD
}
return obj;
}
/**
* A filter used to remove null items from a stream.
*
* @param <T>
* the item type
* @param item
* the item to filter
* @return the item as a steam or an empty stream if the item is {@code null}
*/
@SuppressWarnings("null")
@NonNull
public static <T> Stream<T> filterNull(T item) {
return Objects.nonNull(item) ? Stream.of(item) : Stream.empty();
}
@SuppressWarnings("unchecked")
@NonNull
public static <T> T asType(@NonNull Object obj) {
return (T) obj;
}
@SuppressWarnings("unchecked")
public static <T> T asNullableType(Object obj) {
return (T) obj;
}
}