| /******************************************************************************* |
| * 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.jface.util; |
| |
| |
| /** |
| * <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> |
| * <p> |
| * Note that an <code>assert</code> statement is slated to be added to the |
| * Java language in JDK 1.4, rending this class obsolete. |
| * </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("assertion failed; " + message); //$NON-NLS-1$ |
| 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> |
| * |
| * @param object the value to test |
| * @exception Throwable an unspecified unchecked exception if the object |
| * is <code>null</code> |
| */ |
| 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> |
| * |
| * @param object the value to test |
| * @param message the message to include in the exception |
| * @exception Throwable an unspecified unchecked exception if the object |
| * is <code>null</code> |
| */ |
| 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; |
| } |
| } |