Assert.java
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.shiro.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.
* Usage also reduces a program's
* <a href="http://en.wikipedia.org/wiki/Cyclomatic_complexity">cyclomatic complexity</a>.
*
* <p>For example, if the contract of a public method states it does not
* allow <code>null</code> arguments, Assert can be used to validate that
* contract. Doing this clearly indicates a contract violation when it
* occurs and protects the class's invariants.
*
* <p>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 config initialization code, there is
* usally no point in falling back to defaults in such methods.
*
* <p>This class is similar to JUnit's assertion library. If an argument value is
* deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
* For example:
*
* <pre class="code">
* Assert.notNull(clazz, "The class must not be null");
* Assert.isTrue(i > 0, "The value must be greater than zero");</pre>
*
* Mainly for internal use within the framework; consider Jakarta's Commons Lang
* >= 2.0 for a more comprehensive suite of assertion utilities.
* <p/>
* <em>Gratefully borrowed from the Spring Framework, also Apache 2.0 licensed</em>
*
* @author Keith Donald
* @author Juergen Hoeller
* @author Colin Sampaleanu
* @author Rob Harrop
* @since 1.3
*/
public abstract class Assert {
/**
* Assert a boolean expression, throwing <code>IllegalArgumentException</code>
* if the test result is <code>false</code>.
* <pre class="code">Assert.isTrue(i > 0, "The value must be greater than zero");</pre>
* @param expression a boolean expression
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if expression is <code>false</code>
*/
public static void isTrue(boolean expression, String message) {
if (!expression) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert a boolean expression, throwing <code>IllegalArgumentException</code>
* if the test result is <code>false</code>.
* <pre class="code">Assert.isTrue(i > 0);</pre>
* @param expression a boolean expression
* @throws IllegalArgumentException if expression is <code>false</code>
*/
public static void isTrue(boolean expression) {
isTrue(expression, "[Assertion failed] - this expression must be true");
}
/**
* Assert that an object is <code>null</code> .
* <pre class="code">Assert.isNull(value, "The value must be null");</pre>
* @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</code>
*/
public static void isNull(Object object, String message) {
if (object != null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is <code>null</code> .
* <pre class="code">Assert.isNull(value);</pre>
* @param object the object to check
* @throws IllegalArgumentException if the object is not <code>null</code>
*/
public static void isNull(Object object) {
isNull(object, "[Assertion failed] - the object argument must be null");
}
/**
* Assert that an object is not <code>null</code> .
* <pre class="code">Assert.notNull(clazz, "The class must not be null");</pre>
* @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</code>
*/
public static void notNull(Object object, String message) {
if (object == null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is not <code>null</code> .
* <pre class="code">Assert.notNull(clazz);</pre>
* @param object the object to check
* @throws IllegalArgumentException if the object is <code>null</code>
*/
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</code> and not the empty String.
* <pre class="code">Assert.hasLength(name, "Name must not be empty");</pre>
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @see StringUtils#hasLength
*/
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</code> and not the empty String.
* <pre class="code">Assert.hasLength(name);</pre>
* @param text the String to check
* @see StringUtils#hasLength
*/
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</code> and must contain at least one non-whitespace character.
* <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @see StringUtils#hasText
*/
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</code> and must contain at least one non-whitespace character.
* <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
* @param text the String to check
* @see StringUtils#hasText
*/
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.
* <pre class="code">Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");</pre>
* @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
*/
public static void doesNotContain(String textToSearch, String substring, String message) {
if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
textToSearch.indexOf(substring) != -1) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given text does not contain the given substring.
* <pre class="code">Assert.doesNotContain(name, "rod");</pre>
* @param textToSearch the text to search
* @param substring the substring to find within the text
*/
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</code> and must have at least one element.
* <pre class="code">Assert.notEmpty(array, "The array must have elements");</pre>
* @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</code> or has no elements
*/
public static void notEmpty(Object[] array, String message) {
if (array == null || array.length == 0) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an array has elements; that is, it must not be
* <code>null</code> and must have at least one element.
* <pre class="code">Assert.notEmpty(array);</pre>
* @param array the array to check
* @throws IllegalArgumentException if the object array is <code>null</code> 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!
* <pre class="code">Assert.noNullElements(array, "The array must have non-null elements");</pre>
* @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</code> element
*/
public static void noNullElements(Object[] array, String message) {
if (array != null) {
for (int i = 0; i < array.length; i++) {
if (array[i] == null) {
throw new IllegalArgumentException(message);
}
}
}
}
/**
* Assert that an array has no null elements.
* Note: Does not complain if the array is empty!
* <pre class="code">Assert.noNullElements(array);</pre>
* @param array the array to check
* @throws IllegalArgumentException if the object array contains a <code>null</code> 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</code> and must have at least one element.
* <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
* @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</code> 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</code> and must have at least one element.
* <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
* @param collection the collection to check
* @throws IllegalArgumentException if the collection is <code>null</code> 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</code>
* and must have at least one entry.
* <pre class="code">Assert.notEmpty(map, "Map must have entries");</pre>
* @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</code> 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</code>
* and must have at least one entry.
* <pre class="code">Assert.notEmpty(map);</pre>
* @param map the map to check
* @throws IllegalArgumentException if the map is <code>null</code> 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.
* <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
* @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.
* <pre class="code">Assert.instanceOf(Foo.class, foo);</pre>
* @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 a ": " or ". " so that the function generate message looks
* ok when prepended 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(message +
"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
"] must be an instance of " + type);
}
}
/**
* Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>.
* <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
* @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)</code> is <code>true</code>.
* <pre class="code">Assert.isAssignable(Number.class, myClass);</pre>
* @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 a ": " or ". " so that the function generate message looks
* ok when prepended 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(message + subType + " is not assignable to " + superType);
}
}
/**
* Assert a boolean expression, throwing <code>IllegalStateException</code>
* if the test result is <code>false</code>. Call isTrue if you wish to
* throw IllegalArgumentException on an assertion failure.
* <pre class="code">Assert.state(id == null, "The id property must not already be initialized");</pre>
* @param expression a boolean expression
* @param message the exception message to use if the assertion fails
* @throws IllegalStateException if expression is <code>false</code>
*/
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</code>.
* <p>Call {@link #isTrue(boolean)} if you wish to
* throw {@link IllegalArgumentException} on an assertion failure.
* <pre class="code">Assert.state(id == null);</pre>
* @param expression a boolean expression
* @throws IllegalStateException if the supplied expression is <code>false</code>
*/
public static void state(boolean expression) {
state(expression, "[Assertion failed] - this state invariant must be true");
}
}