/******************************************************************************* | |
* Copyright (c) 2000, 2003 IBM Corporation and others. | |
* All rights reserved. This program and the accompanying materials | |
* are made available under the terms of the Common Public License v1.0 | |
* which accompanies this distribution, and is available at | |
* http://www.eclipse.org/legal/cpl-v10.html | |
* | |
* Contributors: | |
* IBM Corporation - initial API and implementation | |
*******************************************************************************/ | |
package org.eclipse.update.internal.core; | |
/** | |
* <code>Assert</code> is useful for for embedding runtime sanity checks | |
* in code. The static predicate methods all test a condition and throw some | |
* type of unchecked exception if the condition does not hold. | |
* <p> | |
* Assertion failure exceptions, like most runtime exceptions, are | |
* thrown when something is misbehaving. Assertion failures are invariably | |
* unspecified behavior; consequently, clients should never rely on | |
* these being thrown (or not thrown). <b>If you find yourself in the | |
* position where you need to catch an assertion failure, you have most | |
* certainly written your program incorrectly.</b> | |
* </p> | |
*/ | |
public final class Assert { | |
/** | |
* <code>AssertionFailedException</code> is a runtime exception thrown | |
* by some of the methods in <code>Assert</code>. | |
* <p> | |
* This class is not declared public to prevent some misuses; programs that catch | |
* or otherwise depend on assertion failures are susceptible to unexpected | |
* breakage when assertions in the code are added or removed. | |
* </p> | |
*/ | |
private static class AssertionFailedException extends RuntimeException { | |
/** | |
* Constructs a new exception. | |
*/ | |
public AssertionFailedException() { | |
} | |
/** | |
* Constructs a new exception with the given message. | |
*/ | |
public AssertionFailedException(String detail) { | |
super(detail); | |
} | |
} | |
/* This class is not intended to be instantiated. */ | |
private Assert() { | |
} | |
/** | |
* Asserts that an argument is legal. If the given boolean is | |
* not <code>true</code>, an <code>IllegalArgumentException</code> | |
* is thrown. | |
* | |
* @param expression the outcome of the check | |
* @return <code>true</code> if the check passes (does not return | |
* if the check fails) | |
* @exception IllegalArgumentException if the legality test failed | |
*/ | |
public static boolean isLegal(boolean expression) { | |
// succeed as quickly as possible | |
if (expression) { | |
return true; | |
} | |
return isLegal(expression, "");//$NON-NLS-1$ | |
} | |
/** | |
* Asserts that an argument is legal. If the given boolean is | |
* not <code>true</code>, an <code>IllegalArgumentException</code> | |
* is thrown. | |
* The given message is included in that exception, to aid debugging. | |
* | |
* @param expression the outcome of the check | |
* @param message the message to include in the exception | |
* @return <code>true</code> if the check passes (does not return | |
* if the check fails) | |
* @exception IllegalArgumentException if the legality test failed | |
*/ | |
public static boolean isLegal(boolean expression, String message) { | |
if (!expression) | |
throw new IllegalArgumentException(message); | |
return expression; | |
} | |
/** | |
* Asserts that the given object is not <code>null</code>. If this | |
* is not the case, some kind of unchecked exception is thrown. | |
* <p> | |
* As a general rule, parameters passed to API methods must not be | |
* <code>null</code> unless <b>explicitly</b> allowed in the method's | |
* specification. Similarly, results returned from API methods are never | |
* <code>null</code> unless <b>explicitly</b> allowed in the method's | |
* specification. Implementations are encouraged to make regular use of | |
* <code>Assert.isNotNull</code> to ensure that <code>null</code> | |
* parameters are detected as early as possible. | |
* </p> | |
* Method throws an unspecified unchecked exception if the object | |
* is <code>null</code> | |
* @param object the value to test | |
*/ | |
public static void isNotNull(Object object) { | |
// succeed as quickly as possible | |
if (object != null) { | |
return; | |
} | |
isNotNull(object, "");//$NON-NLS-1$ | |
} | |
/** | |
* Asserts that the given object is not <code>null</code>. If this | |
* is not the case, some kind of unchecked exception is thrown. | |
* The given message is included in that exception, to aid debugging. | |
* <p> | |
* As a general rule, parameters passed to API methods must not be | |
* <code>null</code> unless <b>explicitly</b> allowed in the method's | |
* specification. Similarly, results returned from API methods are never | |
* <code>null</code> unless <b>explicitly</b> allowed in the method's | |
* specification. Implementations are encouraged to make regular use of | |
* <code>Assert.isNotNull</code> to ensure that <code>null</code> | |
* parameters are detected as early as possible. | |
* </p> | |
* An unspecified unchecked exception is thrown if the object | |
* is <code>null</code> | |
* @param object the value to test | |
* @param message the message to include in the exception | |
*/ | |
public static void isNotNull(Object object, String message) { | |
if (object == null) | |
throw new AssertionFailedException("null argument;" + message);//$NON-NLS-1$ | |
} | |
/** | |
* Asserts that the given boolean is <code>true</code>. If this | |
* is not the case, some kind of unchecked exception is thrown. | |
* | |
* @param expression the outcome of the check | |
* @return <code>true</code> if the check passes (does not return | |
* if the check fails) | |
*/ | |
public static boolean isTrue(boolean expression) { | |
// succeed as quickly as possible | |
if (expression) { | |
return true; | |
} | |
return isTrue(expression, "");//$NON-NLS-1$ | |
} | |
/** | |
* Asserts that the given boolean is <code>true</code>. If this | |
* is not the case, some kind of unchecked exception is thrown. | |
* The given message is included in that exception, to aid debugging. | |
* | |
* @param expression the outcome of the check | |
* @param message the message to include in the exception | |
* @return <code>true</code> if the check passes (does not return | |
* if the check fails) | |
*/ | |
public static boolean isTrue(boolean expression, String message) { | |
if (!expression) | |
throw new AssertionFailedException("assertion failed; "+message);//$NON-NLS-1$ | |
return expression; | |
} | |
} | |