Checks whether the String contains only digit characters. : String char « Data Type « Java






  1. Java
  2. Data Type
  3. String char

Checks whether the String contains only digit characters.

     

/*
 * 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.
 */


/**
 * <p>Provides extra functionality for Java Number classes.</p>
 *
 * @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>
 * @author Stephen Colebourne
 * @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
 * @author Eric Pugh
 * @author Phil Steitz
 * @author Matthew Hawthorne
 * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
 * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
 * @since 2.0
 * @version $Id: NumberUtils.java 609475 2008-01-06 23:58:59Z bayard $
 */
public class Main {
  /**
   * <p>Checks whether the <code>String</code> contains only
   * digit characters.</p>
   *
   * <p><code>Null</code> and empty String will return
   * <code>false</code>.</p>
   *
   * @param str  the <code>String</code> to check
   * @return <code>true</code> if str contains only unicode numeric
   */
  public static boolean isDigits(String str) {
      if (isEmpty(str)) {
          return false;
      }
      for (int i = 0; i < str.length(); i++) {
          if (!Character.isDigit(str.charAt(i))) {
              return false;
          }
      }
      return true;
  }
  // Empty checks
  //-----------------------------------------------------------------------
  /**
   * <p>Checks if a String is empty ("") or null.</p>
   *
   * <pre>
   * StringUtils.isEmpty(null)      = true
   * StringUtils.isEmpty("")        = true
   * StringUtils.isEmpty(" ")       = false
   * StringUtils.isEmpty("bob")     = false
   * StringUtils.isEmpty("  bob  ") = false
   * </pre>
   *
   * <p>NOTE: This method changed in Lang version 2.0.
   * It no longer trims the String.
   * That functionality is available in isBlank().</p>
   *
   * @param str  the String to check, may be null
   * @return <code>true</code> if the String is empty or null
   */
  public static boolean isEmpty(String str) {
      return str == null || str.length() == 0;
  }
}








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