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/*******************************************************************************
* Copyright (c) 2016, 2017 Obeo.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Obeo - initial API and implementation
*******************************************************************************/
package org.eclipse.eef.common.api.utils;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.stream.Collectors;
/**
* Shared utility methods.
*
* @author Pierre-Charles David <pierre-charles.david@obeo.fr>
*/
public final class Util {
/**
* Prevent instantiation.
*/
private Util() {
// Prevent instantiation.
}
/**
* Returns the first of a series of alternative string values which is not null.
*
* @param alternatives
* the alernative strings, in order of preference.
* @return the first non-null alternative, or an empty string if they are all null.
*/
public static String firstNonNull(String... alternatives) {
for (String s : alternatives) {
if (s != null) {
return s;
}
}
return null;
}
/**
* Tests if a string is blank (i.e. null, empty, or containing only whitespace).
*
* @param s
* the string to test.
* @return <code>true</code> if and only if the string is blank.
*/
public static boolean isBlank(String s) {
return s == null || s.trim().length() == 0;
}
/**
* Returns the given object as a collection and filter it with the given type. If the object is a single object, the
* we will return a collection containing said object, it the object is already a collection, we will return a new
* collection with all its elements.
*
* @param rawValue
* The raw value
* @param clazz
* The class of the result wanted
* @param <T>
* The type of the result wanted
* @return A collection
*/
public static <T> Collection<T> asCollection(Object rawValue, Class<T> clazz) {
final Collection<T> result;
if (rawValue instanceof Collection<?>) {
// @formatter:off
result = ((Collection<?>) rawValue).stream()
.filter(clazz::isInstance)
.map(clazz::cast)
.collect(Collectors.toList());
// @formatter:on
} else if (clazz.isInstance(rawValue)) {
result = Collections.singleton(clazz.cast(rawValue));
} else if (rawValue != null && rawValue.getClass().isArray()) {
// @formatter:off
result = Arrays.stream((Object[]) rawValue)
.filter(clazz::isInstance)
.map(clazz::cast)
.collect(Collectors.toList());
// @formatter:on
} else {
result = Collections.emptySet();
}
return result;
}
}
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