Java String contain only certain characters
public class Main { public static void main(String[] argv) throws Exception { String str = "demo2s.com"; char[] valid = new char[] { 'd', 'e', 'm', 'o', '2', 's', '.' }; System.out.println(containsOnly(str, valid)); }/* www .ja v a 2 s . c om*/ /** * <p> * Checks if the String contains only certain characters. * </p> * * <p> * A <code>null</code> String will return <code>false</code>. A * <code>null</code> valid character array will return <code>false</code>. An * empty String ("") always returns <code>true</code>. * </p> * * <pre> * containsOnly(null, *) = false * containsOnly(*, null) = false * containsOnly("", *) = true * containsOnly("ab", '') = false * containsOnly("abab", 'abc') = true * containsOnly("ab1", 'abc') = false * containsOnly("abz", 'abc') = false * </pre> * * @param str * the String to check, may be null * @param valid * an array of valid chars, may be null * @return true if it only contains valid chars and is non-null */ public static boolean containsOnly(String str, char[] valid) { // All these pre-checks are to maintain API with an older version if ((valid == null) || (str == null)) { return false; } if (str.length() == 0) { return true; } if (valid.length == 0) { return false; } return indexOfAnyBut(str, valid) == -1; } /** * <p> * Checks if the String contains only certain characters. * </p> * * <p> * A <code>null</code> String will return <code>false</code>. A * <code>null</code> valid character String will return <code>false</code>. An * empty String ("") always returns <code>true</code>. * </p> * * <pre> * containsOnly(null, *) = false * containsOnly(*, null) = false * containsOnly("", *) = true * containsOnly("ab", "") = false * containsOnly("abab", "abc") = true * containsOnly("ab1", "abc") = false * containsOnly("abz", "abc") = false * </pre> * * @param str * the String to check, may be null * @param validChars * a String of valid chars, may be null * @return true if it only contains valid chars and is non-null * @since 2.0 */ public static boolean containsOnly(String str, String validChars) { if (str == null || validChars == null) { return false; } return containsOnly(str, validChars.toCharArray()); } /** * <p> * Search a String to find the first index of any character not in the given set * of characters. * </p> * * <p> * A <code>null</code> String will return <code>-1</code>. A <code>null</code> * or zero length search array will return <code>-1</code>. * </p> * * <pre> * indexOfAnyBut(null, *) = -1 * indexOfAnyBut("", *) = -1 * indexOfAnyBut(*, null) = -1 * indexOfAnyBut(*, []) = -1 * indexOfAnyBut("zzabyycdxx",'za') = 3 * indexOfAnyBut("zzabyycdxx", '') = 0 * indexOfAnyBut("aba", 'ab') = -1 * </pre> * * @param str * the String to check, may be null * @param searchChars * the chars to search for, may be null * @return the index of any of the chars, -1 if no match or null input * @since 2.0 */ public static int indexOfAnyBut(String str, char[] searchChars) { if (isEmpty(str) || isArrayEmpty(searchChars)) { return -1; } outer: for (int i = 0; i < str.length(); i++) { char ch = str.charAt(i); for (int j = 0; j < searchChars.length; j++) { if (searchChars[j] == ch) { continue outer; } } return i; } return -1; } /** * <p> * Checks if a String is empty ("") or null. * </p> * * <pre> * isEmpty(null) = true * isEmpty("") = true * isEmpty(" ") = false * isEmpty("bob") = false * 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; } /** * <p> * Checks if an array of primitive chars is empty or <code>null</code>. * </p> * * @param array * the array to test * @return <code>true</code> if the array is empty or <code>null</code> * @since 2.1 */ public static boolean isArrayEmpty(char[] array) { if (array == null || array.length == 0) { return true; } return false; } } /* * 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. */