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Framework to detect and handle differences between Java objects
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/*
 * Copyright 2012 Daniel Bechler
 *
 * Licensed 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 de.danielbechler.util;

import java.util.*;
import java.util.regex.*;

/** @author Daniel Bechler */
public class Strings
{
	private static final Pattern LINE_BREAK_PATTERN = Pattern.compile("\\s*\\n\\s*");

	private Strings()
	{
	}

	@SuppressWarnings("SizeReplaceableByIsEmpty") // String.isEmpty() is a Java 1.6 feature
	public static boolean hasText(final String s)
	{
		return s != null && s.trim().length() != 0;
	}

	public static boolean isEmpty(final String s)
	{
		return !hasText(s);
	}

	/**
	 * Joins all non-null elements of the given elements into one String.
	 *
	 * @param delimiter Inserted as separator between consecutive elements.
	 * @param elements  The elements to join.
	 *
	 * @return A long string containing all non-null elements.
	 */
	public static String join(final String delimiter, final Object... elements)
	{
		final StringBuilder sb = new StringBuilder();
		for (final Object part : elements)
		{
			if (part == null)
			{
				continue;
			}
			if (sb.length() > 0)
			{
				sb.append(delimiter);
			}
			sb.append(part.toString());
		}
		return sb.toString();
	}

	/**
	 * Same as {@link #join(String, Object...)} but with a {@link Collection} instead of an Array for the
	 * elements.
	 *
	 * @see #join(String, java.util.Collection)
	 */
	public static String join(final String delimiter, final Collection elements)
	{
		if (elements == null || elements.isEmpty())
		{
			return "";
		}
		return join(delimiter, elements.toArray(new Object[elements.size()]));
	}

	public static String toSingleLineString(final Object object)
	{
		if (object != null)
		{
			final String s = object.toString().trim();
			final Matcher matcher = LINE_BREAK_PATTERN.matcher(s);
			return matcher.replaceAll(" \\\\ ");
		}
		return null;
	}

	public static String indent(final int times, final String text)
	{
		final StringBuilder sb = new StringBuilder();
		for (int i = 0; i < times; i++)
		{
			sb.append("  ");
		}
		sb.append(text);
		return sb.toString();
	}
}