Here you can find the source of toNullIfEmpty(String string)
public static String toNullIfEmpty(String string)
/*/* ww w. j a v a 2s . co m*/ * Copyright (C) 2000 Google Inc. * * 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. */ import static com.android.mail.lib.base.Preconditions.checkArgument; import com.google.common.base.Joiner; import com.google.common.base.Joiner.MapJoiner; import java.io.IOException; import java.io.InputStream; import java.io.StringWriter; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Set; import java.util.StringTokenizer; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Main{ /** * Old location of {@link Strings#emptyToNull}; this method will be * deprecated soon. */ public static String toNullIfEmpty(String string) { return Strings.emptyToNull(string); } }