Assert


1   /*******************************************************************************
2    * Copyright (c) 2000, 2003 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    * 
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.team.internal.ccvs.core.util;
12  
13  
14  /**
15   * <code>Assert</code> is useful for for embedding runtime sanity checks
16   * in code.
17   * The predicate methods all test a condition and throw some
18   * type of unchecked exception if the condition does not hold.
19   * <p>
20   * Assertion failure exceptions, like most runtime exceptions, are
21   * thrown when something is misbehaving. Assertion failures are invariably
22   * unspecified behavior; consequently, clients should never rely on
23   * these being thrown (and certainly should not being catching them
24   * specifically).
25   * </p>
26   */
27  public final class Assert {
28      /* This class is not intended to be instantiated. */
29      private Assert() {
30      }
31      /** Asserts that an argument is legal. If the given boolean is
32       * not <code>true</code>, an <code>IllegalArgumentException</code>
33       * is thrown.
34       *
35       * @param expression the outcode of the check
36       * @return <code>true</code> if the check passes (does not return
37       *    if the check fails)
38       * @exception IllegalArgumentException if the legality test failed
39       */
40      public static boolean isLegal(boolean expression) {
41          return isLegal(expression, ""); //$NON-NLS-1$
42      }
43      /** Asserts that an argument is legal. If the given boolean is
44       * not <code>true</code>, an <code>IllegalArgumentException</code>
45       * is thrown.
46       * The given message is included in that exception, to aid debugging.
47       *
48       * @param expression the outcode of the check
49       * @param message the message to include in the exception
50       * @return <code>true</code> if the check passes (does not return
51       *    if the check fails)
52       * @exception IllegalArgumentException if the legality test failed
53       */
54      public static boolean isLegal(boolean expression, String   message) {
55          if (!expression)
56              throw new IllegalArgumentException  (message);
57          return expression;
58      }
59      /** Asserts that the given object is not <code>null</code>. If this
60       * is not the case, some kind of unchecked exception is thrown.
61       * 
62       * @param object the value to test
63       * @exception IllegalArgumentException if the object is <code>null</code>
64       */
65      public static void isNotNull(Object   object) {
66          isNotNull(object, ""); //$NON-NLS-1$
67      }
68      /** Asserts that the given object is not <code>null</code>. If this
69       * is not the case, some kind of unchecked exception is thrown.
70       * The given message is included in that exception, to aid debugging.
71       *
72       * @param object the value to test
73       * @param message the message to include in the exception
74       * @exception IllegalArgumentException if the object is <code>null</code>
75       */
76      public static void isNotNull(Object   object, String   message) {
77          if (object == null)
78              throw new AssertionFailedException("null argument:" + message); //$NON-NLS-1$
79      }
80      /** Asserts that the given boolean is <code>true</code>. If this
81       * is not the case, some kind of unchecked exception is thrown.
82       *
83       * @param expression the outcode of the check
84       * @return <code>true</code> if the check passes (does not return
85       *    if the check fails)
86       */
87      public static boolean isTrue(boolean expression) {
88          return isTrue(expression, ""); //$NON-NLS-1$
89      }
90      /** Asserts that the given boolean is <code>true</code>. If this
91       * is not the case, some kind of unchecked exception is thrown.
92       * The given message is included in that exception, to aid debugging.
93       *
94       * @param expression the outcode of the check
95       * @param message the message to include in the exception
96       * @return <code>true</code> if the check passes (does not return
97       *    if the check fails)
98       */
99      public static boolean isTrue(boolean expression, String   message) {
100         if (!expression)
101             throw new AssertionFailedException("assertion failed: " + message); //$NON-NLS-1$
102         return expression;
103     }
104 }
105
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