Mega Code Archive
Assertion utility class that assists in validating arguments
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/*
* Copyright 2002-2007 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 jacky.lanlan.song.extension.struts.util;
/**
* Assertion utility class that assists in validating arguments.
* Useful for identifying programmer errors early and clearly at runtime.
*
* <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.
*
* @author Keith Donald
* @author Juergen Hoeller
* @author Colin Sampaleanu
* @author Rob Harrop
* @since 1.1.2
*/
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 a boolean expression, throwing <code>IllegalArgumentException</code>
* if the test result is <code>true</code>.
* <pre class="code">Assert.isFalse(i > 0);</pre>
* @param expression a boolean expression
* @throws IllegalArgumentException if expression is <code>true</code>
*/
public static void isFalse(boolean expression) {
isTrue(!expression, "[Assertion failed] - this expression must be false");
}
/**
* Assert a boolean expression, throwing <code>IllegalArgumentException</code>
* if the test result is <code>true</code>.
* <pre class="code">Assert.isFalse(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>true</code>
*/
public static void isFalse(boolean expression, String message) {
isTrue(!expression, message);
}
/**
* 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 <code>null</code> 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 <code>null</code>, 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 + "]");
}
}
/**
* Miscellaneous {@link String} utility methods.
*
* <p>Mainly for internal use within the framework; consider
* <a href="http://jakarta.apache.org/commons/lang/">Jakarta's Commons Lang</a>
* for a more comprehensive suite of
* {@link org.apache.commons.lang.StringUtils String utilities}.
*
* <p>This class delivers some simple functionality that should really
* be provided by the core Java <code>String</code> and {@link StringBuffer}
* classes, such as the ability to {@link #replace} all occurrences of a given
* substring in a target string. It also provides easy-to-use methods to
* convert between delimited strings, such as CSV strings, and collections and
* arrays.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Keith Donald
* @author Rob Harrop
* @author Rick Evans
* @author Jacky.Song
* @since 16 April 2001
*/
abstract class StringUtils {
/**
* Check that the given String is neither <code>null</code> nor of length 0.
* Note: Will return <code>true</code> for a String that purely consists of whitespace.
* <p><pre>
* StringUtils.hasLength(null) = false
* StringUtils.hasLength("") = false
* StringUtils.hasLength(" ") = true
* StringUtils.hasLength("Hello") = true
* </pre>
* @param str the String to check (may be <code>null</code>)
* @return <code>true</code> if the String is not null and has length
* @see #hasText(String)
*/
public static boolean hasLength(String str) {
return (str != null && str.length() > 0);
}
/**
* Check whether the given String has actual text.
* More specifically, returns <code>true</code> if the string not <code>null</code>,
* its length is greater than 0, and it contains at least one non-whitespace character.
* <p><pre>
* StringUtils.hasText(null) = false
* StringUtils.hasText("") = false
* StringUtils.hasText(" ") = false
* StringUtils.hasText("12345") = true
* StringUtils.hasText(" 12345 ") = true
* </pre>
* @param str the String to check (may be <code>null</code>)
* @return <code>true</code> if the String is not <code>null</code>, its length is
* greater than 0, and it does not contain whitespace only
* @see java.lang.Character#isWhitespace
*/
public static boolean hasText(String str) {
if (!hasLength(str)) {
return false;
}
int strLen = str.length();
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
}
/**
* Check whether the given String contains any whitespace characters.
* @param str the String to check (may be <code>null</code>)
* @return <code>true</code> if the String is not empty and
* contains at least 1 whitespace character
* @see java.lang.Character#isWhitespace
*/
public static boolean containsWhitespace(String str) {
if (!hasLength(str)) {
return false;
}
int strLen = str.length();
for (int i = 0; i < strLen; i++) {
if (Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
}
/**
* Capitalize a <code>String</code>, changing the first letter to
* upper case as per {@link Character#toUpperCase(char)}.
* No other letters are changed.
* @param str the String to capitalize, may be <code>null</code>
* @return the capitalized String, <code>null</code> if null
*/
public static String capitalize(String str) {
return changeFirstCharacterCase(str, true);
}
/**
* Uncapitalize a <code>String</code>, changing the first letter to
* lower case as per {@link Character#toLowerCase(char)}.
* No other letters are changed.
* @param str the String to uncapitalize, may be <code>null</code>
* @return the uncapitalized String, <code>null</code> if null
*/
public static String uncapitalize(String str) {
return changeFirstCharacterCase(str, false);
}
private static String changeFirstCharacterCase(String str, boolean capitalize) {
if (str == null || str.length() == 0) {
return str;
}
StringBuffer buf = new StringBuffer(str.length());
if (capitalize) {
buf.append(Character.toUpperCase(str.charAt(0)));
}
else {
buf.append(Character.toLowerCase(str.charAt(0)));
}
buf.append(str.substring(1));
return buf.toString();
}
}
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