Java tutorial
/* * 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. */ package org.apache.commons.lang; import java.util.Collection; import java.util.Iterator; import java.util.Map; /** * <p>Assists in validating arguments.</p> * * <p>The class is based along the lines of JUnit. If an argument value is * deemed invalid, an IllegalArgumentException is thrown. For example:</p> * * <pre> * Validate.isTrue( i > 0, "The value must be greater than zero: ", i); * Validate.notNull( surname, "The surname must not be null"); * </pre> * * @author <a href="mailto:ola.berg@arkitema.se">Ola Berg</a> * @author Stephen Colebourne * @author Gary Gregory * @author Norm Deane * @since 2.0 * @version $Id: Validate.java 437554 2006-08-28 06:21:41Z bayard $ */ public class Validate { // Validate has no dependencies on other classes in Commons Lang at present /** * Constructor. This class should not normally be instantiated. */ public Validate() { super(); } // isTrue //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>.</p> * * <p>This is used when validating according to an arbitrary boolean expression, * such as validating a primitive number or using your own custom validation * expression.</p> * * <pre> * Validate.isTrue( myObject.isOk(), "The object is not OK: ", myObject); * </pre> * * <p>For performance reasons, the object is passed as a separate parameter and * appended to the message string only in the case of an error.</p> * * @param expression a boolean expression * @param message the exception message you would like to see if the * expression is <code>false</code> * @param value the value to append to the message in case of error * @throws IllegalArgumentException if expression is <code>false</code> */ public static void isTrue(boolean expression, String message, Object value) { if (expression == false) { throw new IllegalArgumentException(message + value); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>.</p> * * <p>This is used when validating according to an arbitrary boolean expression, * such as validating a primitive number or using your own custom validation * expression.</p> * * <pre> * Validate.isTrue( i > 0, "The value must be greater than zero: ", i); * </pre> * * <p>For performance reasons, the long value is passed as a separate parameter and * appended to the message string only in the case of an error.</p> * * @param expression a boolean expression * @param message the exception message you would like to see if the expression is <code>false</code> * @param value the value to append to the message in case of error * @throws IllegalArgumentException if expression is <code>false</code> */ public static void isTrue(boolean expression, String message, long value) { if (expression == false) { throw new IllegalArgumentException(message + value); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>.</p> * * <p>This is used when validating according to an arbitrary boolean expression, * such as validating a primitive number or using your own custom validation * expression.</p> * * <pre> * Validate.isTrue( d > 0.0, "The value must be greater than zero: ", d); * </pre> * * <p>For performance reasons, the double value is passed as a separate parameter and * appended to the message string only in the case of an error.</p> * * @param expression a boolean expression * @param message the exception message you would like to see if the expression * is <code>false</code> * @param value the value to append to the message in case of error * @throws IllegalArgumentException if expression is <code>false</code> */ public static void isTrue(boolean expression, String message, double value) { if (expression == false) { throw new IllegalArgumentException(message + value); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>.</p> * * <p>This is used when validating according to an arbitrary boolean expression, * such as validating a primitive number or using your own custom validation * expression.</p> * * <pre> * Validate.isTrue( (i > 0), "The value must be greater than zero"); * Validate.isTrue( myObject.isOk(), "The object is not OK"); * </pre> * * <p>For performance reasons, the message string should not involve a string append, * instead use the {@link #isTrue(boolean, String, Object)} method.</p> * * @param expression a boolean expression * @param message the exception message you would like to see if the expression * is <code>false</code> * @throws IllegalArgumentException if expression is <code>false</code> */ public static void isTrue(boolean expression, String message) { if (expression == false) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>.</p> * * <p>This is used when validating according to an arbitrary boolean expression, * such as validating a primitive number or using your own custom validation * expression.</p> * * <pre> * Validate.isTrue( i > 0 ); * Validate.isTrue( myObject.isOk() ); * </pre> * * <p>The message in the exception is 'The validated expression is false'.</p> * * @param expression a boolean expression * @throws IllegalArgumentException if expression is <code>false</code> */ public static void isTrue(boolean expression) { if (expression == false) { throw new IllegalArgumentException("The validated expression is false"); } } // notNull //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument is <code>null</code>.</p> * * <pre> * Validate.notNull(myObject, "The object must not be null"); * </pre> * * @param object the object to check is not <code>null</code> * @param message the exception message you would like to see * if the object is <code>null</code> * @throws IllegalArgumentException if the object is <code>null</code> */ public static void notNull(Object object, String message) { if (object == null) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument is <code>null</code>.</p> * * <pre> * Validate.notNull(myObject); * </pre> * * <p>The message in the exception is 'The validated object is null'.</p> * * @param object the object to check is not <code>null</code> * @throws IllegalArgumentException if the object is <code>null</code> */ public static void notNull(Object object) { if (object == null) { throw new IllegalArgumentException("The validated object is null"); } } // notEmpty array //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument array is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myArray, "The array must not be empty"); * </pre> * * @param array the array to check is not empty * @param message the exception message you would like to see if the array is empty * @throws IllegalArgumentException if the array is empty */ public static void notEmpty(Object[] array, String message) { if (array == null || array.length == 0) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument array is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myArray); * </pre> * * <p>The message in the exception is 'The validated array is empty'. * * @param array the array to check is not empty * @throws IllegalArgumentException if the array is empty */ public static void notEmpty(Object[] array) { if (array == null || array.length == 0) { throw new IllegalArgumentException("The validated array is empty"); } } // notEmpty collection //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Collection is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myCollection, "The collection must not be empty"); * </pre> * * @param collection the collection to check is not empty * @param message the exception message you would like to see if the collection is empty * @throws IllegalArgumentException if the collection is empty */ public static void notEmpty(Collection collection, String message) { if (collection == null || collection.size() == 0) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Collection is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myCollection); * </pre> * * <p>The message in the exception is 'The validated collection is empty'.</p> * * @param collection the collection to check is not empty * @throws IllegalArgumentException if the collection is empty */ public static void notEmpty(Collection collection) { if (collection == null || collection.size() == 0) { throw new IllegalArgumentException("The validated collection is empty"); } } // notEmpty map //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Map is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myMap, "The map must not be empty"); * </pre> * * @param map the map to check is not empty * @param message the exception message you would like to see if the map is empty * @throws IllegalArgumentException if the map is empty */ public static void notEmpty(Map map, String message) { if (map == null || map.size() == 0) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Map is empty (<code>null</code> or no elements).</p> * * <pre> * Validate.notEmpty(myMap); * </pre> * * <p>The message in the exception is 'The validated map is empty'.</p> * * @param map the map to check is not empty * @throws IllegalArgumentException if the map is empty */ public static void notEmpty(Map map) { if (map == null || map.size() == 0) { throw new IllegalArgumentException("The validated map is empty"); } } // notEmpty string //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument String is empty (<code>null</code> or zero length).</p> * * <pre> * Validate.notEmpty(myString, "The string must not be empty"); * </pre> * * @param string the string to check is not empty * @param message the exception message you would like to see if the string is empty * @throws IllegalArgumentException if the string is empty */ public static void notEmpty(String string, String message) { if (string == null || string.length() == 0) { throw new IllegalArgumentException(message); } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument String is empty (<code>null</code> or zero length).</p> * * <pre> * Validate.notEmpty(myString); * </pre> * * <p>The message in the exception is 'The validated string is empty'.</p> * * @param string the string to check is not empty * @throws IllegalArgumentException if the string is empty */ public static void notEmpty(String string) { if (string == null || string.length() == 0) { throw new IllegalArgumentException("The validated string is empty"); } } // notNullElements array //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument array has <code>null</code> elements or is * <code>null</code>.</p> * * <pre> * Validate.noNullElements(myArray, "The array must not contain null elements"); * </pre> * * <p>If the array is null then the message in the exception is 'The validated object is null'.</p> * * @param array the array to check * @param message the exception message if the array has * <code>null</code> elements * @throws IllegalArgumentException if the array has <code>null</code> * elements or is <code>null</code> */ public static void noNullElements(Object[] array, String message) { Validate.notNull(array); for (int i = 0; i < array.length; i++) { if (array[i] == null) { throw new IllegalArgumentException(message); } } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument array has <code>null</code> elements or is * <code>null</code>.</p> * * <pre> * Validate.noNullElements(myArray); * </pre> * * <p>If the array has a null element the message in the exception is * 'The validated array contains null element at index: '.</p> * * <p>If the array is null then the message in the exception is 'The validated object is null'.</p> * * @param array the array to check * @throws IllegalArgumentException if the array has <code>null</code> * elements or is <code>null</code> */ public static void noNullElements(Object[] array) { Validate.notNull(array); for (int i = 0; i < array.length; i++) { if (array[i] == null) { throw new IllegalArgumentException("The validated array contains null element at index: " + i); } } } // notNullElements collection //--------------------------------------------------------------------------------- /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Collection has <code>null</code> elements or is * <code>null</code>.</p> * * <pre> * Validate.noNullElements(myCollection, "The collection must not contain null elements"); * </pre> * * <p>If the collection is null then the message in the exception is 'The validated object is null'.</p> * * @param collection the collection to check * @param message the exception message if the collection has * <code>null</code> elements * @throws IllegalArgumentException if the collection has * <code>null</code> elements or is <code>null</code> */ public static void noNullElements(Collection collection, String message) { Validate.notNull(collection); for (Iterator it = collection.iterator(); it.hasNext();) { if (it.next() == null) { throw new IllegalArgumentException(message); } } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument Collection has <code>null</code> elements or is * <code>null</code>.</p> * * <pre> * Validate.noNullElements(myCollection); * </pre> * * <p>The message in the exception is 'The validated collection contains null element at index: '.</p> * * <p>If the collection is null then the message in the exception is 'The validated object is null'.</p> * * @param collection the collection to check * @throws IllegalArgumentException if the collection has * <code>null</code> elements or is <code>null</code> */ public static void noNullElements(Collection collection) { Validate.notNull(collection); int i = 0; for (Iterator it = collection.iterator(); it.hasNext(); i++) { if (it.next() == null) { throw new IllegalArgumentException("The validated collection contains null element at index: " + i); } } } /** * <p>Validate an argument, throwing <code>IllegalArgumentException</code> * if the argument collection is <code>null</code> or has elements that * are not of type <code>clazz</code> or a subclass.</p> * * <pre> * Validate.allElementsOfType(collection, String.class, "Collection has invalid elements"); * </pre> * * @param collection the collection to check, not null * @param clazz the <code>Class</code> which the collection's elements are expected to be, not null * @param message the exception message if the <code>Collection</code> has elements not of type <code>clazz</code> * @since 2.1 */ public static void allElementsOfType(Collection collection, Class clazz, String message) { Validate.notNull(collection); Validate.notNull(clazz); for (Iterator it = collection.iterator(); it.hasNext();) { if (clazz.isInstance(it.next()) == false) { throw new IllegalArgumentException(message); } } } /** * <p> * Validate an argument, throwing <code>IllegalArgumentException</code> if the argument collection is * <code>null</code> or has elements that are not of type <code>clazz</code> or a subclass. * </p> * * <pre> * Validate.allElementsOfType(collection, String.class); * </pre> * * <p> * The message in the exception is 'The validated collection contains an element not of type clazz at index: '. * </p> * * @param collection * the collection to check, not null * @param clazz * the <code>Class</code> which the collection's elements are expected to be, not null * @since 2.1 */ public static void allElementsOfType(Collection collection, Class clazz) { Validate.notNull(collection); Validate.notNull(clazz); int i = 0; for (Iterator it = collection.iterator(); it.hasNext(); i++) { if (clazz.isInstance(it.next()) == false) { throw new IllegalArgumentException("The validated collection contains an element not of type " + clazz.getName() + " at index: " + i); } } } }