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Commons Digester example source code file (TestRecursion.java)

This example Commons Digester source code file (TestRecursion.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Digester tags/keywords

container, container, digester, digester, exception, list, plugincreaterule, plugindeclarationrule, plugindeclarationrule, pluginrules, pluginrules, test, testrecursion, util

The Commons Digester TestRecursion.java source code

/* $Id: TestRecursion.java 992060 2010-09-02 19:09:47Z simonetripodi $
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.apache.commons.digester.plugins;

import static org.junit.Assert.*;

import java.util.List;

import org.apache.commons.digester.Digester;
import org.junit.Test;

 * Test cases for plugins with custom rules which include PluginCreateRule
 * instances, allowing recursive datastructures to be processed.

public class TestRecursion {

    // --------------------------------------------------------------- Test cases
    public void testRecursiveRules() throws Exception {
        // * tests that a rule can declare custom PluginCreateRules
        //   that allow it to plug in instances of itself below
        //   itself.

        Digester digester = new Digester();
        PluginRules rc = new PluginRules();
        PluginDeclarationRule pdr = new PluginDeclarationRule();
        digester.addRule("*/plugin", pdr);
        PluginCreateRule pcr = new PluginCreateRule(Widget.class);
        digester.addRule("root/widget", pcr);
        digester.addSetNext("root/widget", "addChild");

        Container root = new Container();
        try {
                Utils.getInputStream(this, "test6.xml"));
        catch(Exception e) {
            throw e;
        int nDescendants = countWidgets(root);
        assertEquals(10, nDescendants);

    private int countWidgets(Container c) {
        List<Widget> l = c.getChildren();
        int sum = 0;
        for(Widget w : l) {
            if (w instanceof Container) {
                sum += countWidgets((Container) w);
        return sum;

Other Commons Digester examples (source code examples)

Here is a short list of links related to this Commons Digester TestRecursion.java source code file:

my book on functional programming


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