/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache 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.apache.org/licenses/LICENSE-2.0
*
* 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.apache.tomcat.util.buf;
import java.util.Arrays;
import java.util.Collection;
import java.util.function.Function;
/**
* Utility methods to build a separated list from a given set (not java.util.Set) of inputs and return that list as a
* string or append it to an existing StringBuilder. If the given set is null or empty, an empty string will be
* returned.
*/
public final class StringUtils {
private static final String EMPTY_STRING = "";
private StringUtils() {
// Utility class
}
public static String join(String a, String b) {
return join(new String[] { a, b });
}
public static String join(String[] array) {
if (array == null) {
return EMPTY_STRING;
}
return join(Arrays.asList(array));
}
public static void join(String[] array, char separator, StringBuilder sb) {
if (array == null) {
return;
}
join(Arrays.asList(array), separator, sb);
}
public static String join(Collection<String> collection) {
return join(collection, ',');
}
public static String join(Collection<String> collection, char separator) {
// Shortcut
if (collection == null || collection.isEmpty()) {
return EMPTY_STRING;
}
StringBuilder result = new StringBuilder();
join(collection, separator, result);
return result.toString();
}
public static void join(Iterable<String> iterable, char separator, StringBuilder sb) {
join(iterable, separator, (x) -> x, sb);
}
public static <T> void join(T[] array, char separator, Function<T,String> function, StringBuilder sb) {
if (array == null) {
return;
}
join(Arrays.asList(array), separator, function, sb);
}
public static <T> void join(Iterable<T> iterable, char separator, Function<T,String> function, StringBuilder sb) {
if (iterable == null) {
return;
}
boolean first = true;
for (T value : iterable) {
if (first) {
first = false;
} else {
sb.append(separator);
}
sb.append(function.apply(value));
}
}
/**
* Splits a comma-separated string into an array of String values. Whitespace around the commas is removed. Null or
* empty values will return a zero-element array.
*
* @param s The string to split by commas.
*
* @return An array of String values.
*/
public static String[] splitCommaSeparated(String s) {
if (s == null || s.isEmpty()) {
return new String[0];
}
String[] splits = s.split(",");
for (int i = 0; i < splits.length; ++i) {
splits[i] = splits[i].trim();
}
return splits;
}
}