/*
* Copyright 2003-2004 The Apache Software Foundation
*
* 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 org.apache.commons.attributes;
import java.util.Iterator;
import java.util.List;
/**
* Thrown when an attribute repository class can't be
* loaded because it resulted in a circular dependency.
*
* @since 2.1
*/
public class CircularDependencyError extends RepositoryError {
/**
* Create a new CircularDependencyError.
*
* @param className the name of the class that started it all.
* @param dependencyList a list of the classes ({@link java.lang.Class})
* that the original
* class depended on, the classes they
* depended on, and so on. The list should
* show the chain of dependencies that resulted
* in the exception being thrown. <b>Note</b>:
* Versions prior to 2.2 accepted a list of Objects
* of any type. This is still supported, but the
* formatting may suffer. Please only use lists of
* {@link java.lang.Class}.
*
* @since 2.1
*/
public CircularDependencyError (String className, List dependencyList) {
super (className + ":" + listDeps (dependencyList), null);
}
/**
* Joins together the elements of a list with <code>-></code>
* delimiters. Used to show the sequence that resulted in the circular
* dependency.
*
* @since 2.1
*/
private static String listDeps (List dependencyList) {
StringBuffer sb = new StringBuffer ();
Iterator iter = dependencyList.iterator ();
while (iter.hasNext ()) {
Object o = iter.next ();
// Test that the user really passed in a Class. Versions
// prior to 2.2 received Strings instead, and any user that
// used the code would find it broken.
if (o != null && o instanceof Class) {
sb.append (((Class) o).getName ());
} else {
sb.append (o);
}
if (iter.hasNext ()) {
sb.append (" -> ");
}
}
return sb.toString ();
}
}