org.springframework.util.Assert Maven / Gradle / Ivy
/*
* Copyright 2002-2015 the original author or authors.
*
* 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.
*/
package org.springframework.util;
import java.util.Collection;
import java.util.Map;
/**
* Assertion utility class that assists in validating arguments.
*
* Useful for identifying programmer errors early and clearly at runtime.
*
*
For example, if the contract of a public method states it does not
* allow {@code null} arguments, {@code Assert} can be used to validate that
* contract. Doing this clearly indicates a contract violation when it
* occurs and protects the class's invariants.
*
*
Typically used to validate method arguments rather than configuration
* properties, to check for cases that are usually programmer errors rather
* than configuration errors. In contrast to configuration initialization
* code, there is usually no point in falling back to defaults in such methods.
*
*
This class is similar to JUnit's assertion library. If an argument value is
* deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
* For example:
*
*
* Assert.notNull(clazz, "The class must not be null");
* Assert.isTrue(i > 0, "The value must be greater than zero");
*
* Mainly for internal use within the framework; consider
* Apache's Commons Lang
* for a more comprehensive suite of {@code String} utilities.
*
* @author Keith Donald
* @author Juergen Hoeller
* @author Colin Sampaleanu
* @author Rob Harrop
* @author Sam Brannen
* @since 1.1.2
*/
public abstract class Assert {
/**
* Assert a boolean expression, throwing {@code IllegalArgumentException}
* if the test result is {@code false}.
*
Assert.isTrue(i > 0, "The value must be greater than zero");
* @param expression a boolean expression
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if expression is {@code false}
*/
public static void isTrue(boolean expression, String message) {
if (!expression) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert a boolean expression, throwing {@code IllegalArgumentException}
* if the test result is {@code false}.
* Assert.isTrue(i > 0);
* @param expression a boolean expression
* @throws IllegalArgumentException if expression is {@code false}
*/
public static void isTrue(boolean expression) {
isTrue(expression, "[Assertion failed] - this expression must be true");
}
/**
* Assert that an object is {@code null} .
* Assert.isNull(value, "The value must be null");
* @param object the object to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the object is not {@code null}
*/
public static void isNull(Object object, String message) {
if (object != null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is {@code null} .
* Assert.isNull(value);
* @param object the object to check
* @throws IllegalArgumentException if the object is not {@code null}
*/
public static void isNull(Object object) {
isNull(object, "[Assertion failed] - the object argument must be null");
}
/**
* Assert that an object is not {@code null} .
* Assert.notNull(clazz, "The class must not be null");
* @param object the object to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the object is {@code null}
*/
public static void notNull(Object object, String message) {
if (object == null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is not {@code null} .
* Assert.notNull(clazz);
* @param object the object to check
* @throws IllegalArgumentException if the object is {@code null}
*/
public static void notNull(Object object) {
notNull(object, "[Assertion failed] - this argument is required; it must not be null");
}
/**
* Assert that the given String is not empty; that is,
* it must not be {@code null} and not the empty String.
* Assert.hasLength(name, "Name must not be empty");
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @see StringUtils#hasLength
* @throws IllegalArgumentException if the text is empty
*/
public static void hasLength(String text, String message) {
if (!StringUtils.hasLength(text)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given String is not empty; that is,
* it must not be {@code null} and not the empty String.
* Assert.hasLength(name);
* @param text the String to check
* @see StringUtils#hasLength
* @throws IllegalArgumentException if the text is empty
*/
public static void hasLength(String text) {
hasLength(text,
"[Assertion failed] - this String argument must have length; it must not be null or empty");
}
/**
* Assert that the given String has valid text content; that is, it must not
* be {@code null} and must contain at least one non-whitespace character.
* Assert.hasText(name, "'name' must not be empty");
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @see StringUtils#hasText
* @throws IllegalArgumentException if the text does not contain valid text content
*/
public static void hasText(String text, String message) {
if (!StringUtils.hasText(text)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given String has valid text content; that is, it must not
* be {@code null} and must contain at least one non-whitespace character.
* Assert.hasText(name, "'name' must not be empty");
* @param text the String to check
* @see StringUtils#hasText
* @throws IllegalArgumentException if the text does not contain valid text content
*/
public static void hasText(String text) {
hasText(text,
"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
}
/**
* Assert that the given text does not contain the given substring.
* Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");
* @param textToSearch the text to search
* @param substring the substring to find within the text
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the text contains the substring
*/
public static void doesNotContain(String textToSearch, String substring, String message) {
if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
textToSearch.contains(substring)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given text does not contain the given substring.
* Assert.doesNotContain(name, "rod");
* @param textToSearch the text to search
* @param substring the substring to find within the text
* @throws IllegalArgumentException if the text contains the substring
*/
public static void doesNotContain(String textToSearch, String substring) {
doesNotContain(textToSearch, substring,
"[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
}
/**
* Assert that an array has elements; that is, it must not be
* {@code null} and must have at least one element.
* Assert.notEmpty(array, "The array must have elements");
* @param array the array to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the object array is {@code null} or has no elements
*/
public static void notEmpty(Object[] array, String message) {
if (ObjectUtils.isEmpty(array)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an array has elements; that is, it must not be
* {@code null} and must have at least one element.
* Assert.notEmpty(array);
* @param array the array to check
* @throws IllegalArgumentException if the object array is {@code null} or has no elements
*/
public static void notEmpty(Object[] array) {
notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
}
/**
* Assert that an array has no null elements.
* Note: Does not complain if the array is empty!
* Assert.noNullElements(array, "The array must have non-null elements");
* @param array the array to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the object array contains a {@code null} element
*/
public static void noNullElements(Object[] array, String message) {
if (array != null) {
for (Object element : array) {
if (element == null) {
throw new IllegalArgumentException(message);
}
}
}
}
/**
* Assert that an array has no null elements.
* Note: Does not complain if the array is empty!
* Assert.noNullElements(array);
* @param array the array to check
* @throws IllegalArgumentException if the object array contains a {@code null} element
*/
public static void noNullElements(Object[] array) {
noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
}
/**
* Assert that a collection has elements; that is, it must not be
* {@code null} and must have at least one element.
* Assert.notEmpty(collection, "Collection must have elements");
* @param collection the collection to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the collection is {@code null} or has no elements
*/
public static void notEmpty(Collection collection, String message) {
if (CollectionUtils.isEmpty(collection)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that a collection has elements; that is, it must not be
* {@code null} and must have at least one element.
* Assert.notEmpty(collection, "Collection must have elements");
* @param collection the collection to check
* @throws IllegalArgumentException if the collection is {@code null} or has no elements
*/
public static void notEmpty(Collection collection) {
notEmpty(collection,
"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
}
/**
* Assert that a Map has entries; that is, it must not be {@code null}
* and must have at least one entry.
* Assert.notEmpty(map, "Map must have entries");
* @param map the map to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the map is {@code null} or has no entries
*/
public static void notEmpty(Map map, String message) {
if (CollectionUtils.isEmpty(map)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that a Map has entries; that is, it must not be {@code null}
* and must have at least one entry.
* Assert.notEmpty(map);
* @param map the map to check
* @throws IllegalArgumentException if the map is {@code null} or has no entries
*/
public static void notEmpty(Map map) {
notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
}
/**
* Assert that the provided object is an instance of the provided class.
* Assert.instanceOf(Foo.class, foo);
* @param clazz the required class
* @param obj the object to check
* @throws IllegalArgumentException if the object is not an instance of clazz
* @see Class#isInstance
*/
public static void isInstanceOf(Class clazz, Object obj) {
isInstanceOf(clazz, obj, "");
}
/**
* Assert that the provided object is an instance of the provided class.
* Assert.instanceOf(Foo.class, foo);
* @param type the type to check against
* @param obj the object to check
* @param message a message which will be prepended to the message produced by
* the function itself, and which may be used to provide context. It should
* normally end in ":" or "." so that the generated message looks OK when
* appended to it.
* @throws IllegalArgumentException if the object is not an instance of clazz
* @see Class#isInstance
*/
public static void isInstanceOf(Class type, Object obj, String message) {
notNull(type, "Type to check against must not be null");
if (!type.isInstance(obj)) {
throw new IllegalArgumentException(
(StringUtils.hasLength(message) ? message + " " : "") +
"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
"] must be an instance of " + type);
}
}
/**
* Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
* Assert.isAssignable(Number.class, myClass);
* @param superType the super type to check
* @param subType the sub type to check
* @throws IllegalArgumentException if the classes are not assignable
*/
public static void isAssignable(Class superType, Class subType) {
isAssignable(superType, subType, "");
}
/**
* Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
* Assert.isAssignable(Number.class, myClass);
* @param superType the super type to check against
* @param subType the sub type to check
* @param message a message which will be prepended to the message produced by
* the function itself, and which may be used to provide context. It should
* normally end in ":" or "." so that the generated message looks OK when
* appended to it.
* @throws IllegalArgumentException if the classes are not assignable
*/
public static void isAssignable(Class superType, Class subType, String message) {
notNull(superType, "Type to check against must not be null");
if (subType == null || !superType.isAssignableFrom(subType)) {
throw new IllegalArgumentException((StringUtils.hasLength(message) ? message + " " : "")
+ subType + " is not assignable to " + superType);
}
}
/**
* Assert a boolean expression, throwing {@code IllegalStateException}
* if the test result is {@code false}. Call isTrue if you wish to
* throw IllegalArgumentException on an assertion failure.
* Assert.state(id == null, "The id property must not already be initialized");
* @param expression a boolean expression
* @param message the exception message to use if the assertion fails
* @throws IllegalStateException if expression is {@code false}
*/
public static void state(boolean expression, String message) {
if (!expression) {
throw new IllegalStateException(message);
}
}
/**
* Assert a boolean expression, throwing {@link IllegalStateException}
* if the test result is {@code false}.
* Call {@link #isTrue(boolean)} if you wish to
* throw {@link IllegalArgumentException} on an assertion failure.
*
Assert.state(id == null);
* @param expression a boolean expression
* @throws IllegalStateException if the supplied expression is {@code false}
*/
public static void state(boolean expression) {
state(expression, "[Assertion failed] - this state invariant must be true");
}
}