Android String Empty Check toNullIfEmptyOrWhitespace(String string)

Description

Returns the given string if it is nonempty and contains at least one non-whitespace character; null otherwise.

License

Apache License

Parameter

Parameter	Description
string	the string to test and possibly return

Return

null if string is null, empty, or contains only whitespace characters; string itself otherwise

Declaration

public static String toNullIfEmptyOrWhitespace(String string)

Method Source Code

/*/*w  ww  .j a  v a  2  s.  c  om*/
  * 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{
    /**
      * Returns the given string if it is nonempty and contains at least one
      * non-whitespace character; {@code null} otherwise. See comment in {@link
      * #isEmptyOrWhitespace} on the definition of whitespace.
      *
      * @param string the string to test and possibly return
      * @return {@code null} if {@code string} is null, empty, or contains only
      *     whitespace characters; {@code string} itself otherwise
      */
     public static String toNullIfEmptyOrWhitespace(String string) {
         return isEmptyOrWhitespace(string) ? null : string;
     }
    /**
      * Returns {@code true} if the given string is null, empty, or comprises only
      * whitespace characters, as defined by {@link CharMatcher#WHITESPACE}.
      *
      * <p><b>Warning:</b> there are many competing definitions of "whitespace";
      * please see <a href="http://go/white+space">this spreadsheet</a> for
      * details.
      *
      * @param string the string reference to check
      * @return {@code true} if {@code string} is null, empty, or consists of
      *     whitespace characters only
      */
     public static boolean isEmptyOrWhitespace(String string) {
         return string == null
                 || CharMatcher.WHITESPACE.matchesAllOf(string);
     }
}