Add org.apache.commons.collections4.properties.OrderedProperties and

OrderedPropertiesFactory

pom.xml

@@ -647,7 +647,7 @@
           <suppressionsLocation>${basedir}/src/conf/checkstyle-suppressions.xml</suppressionsLocation>
           <enableRulesSummary>false</enableRulesSummary>
           <includeTestSourceDirectory>true</includeTestSourceDirectory>
-          <resourceExcludes>NOTICE.txt,LICENSE.txt,**/pom.properties,**/test.properties,**/resolver-status.properties</resourceExcludes>
+          <resourceExcludes>NOTICE.txt,LICENSE.txt,**/pom.properties,**/test*.properties,**/resolver-status.properties</resourceExcludes>
         </configuration>
       </plugin>
       <plugin>

src/changes/changes.xml

@@ -270,6 +270,9 @@
     <action issue="COLLECTIONS-746" dev="ggregory" type="add" due-to="Gary Gregory">
       Add PropertiesFactory.
     </action>
+    <action dev="ggregory" type="add" due-to="Gary Gregory">
+      Add org.apache.commons.collections4.properties.OrderedProperties and OrderedPropertiesFactory.
+    </action>
     <!-- UPDATE -->
     <action dev="ggregory" type="update" due-to="Gary Gregory, Dependabot">
       Bump org.easymock:easymock from 4.0.2 to 5.1.0 #352, #355, #375.

src/main/java/org/apache/commons/collections4/properties/OrderedProperties.java

@@ -0,0 +1,133 @@
+/*
+ * 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,
+ * 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.collections4.properties;
+
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Properties;
+import java.util.Set;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+
+/**
+ * A drop-in replacement for {@link Properties} for ordered keys.
+ * <p>
+ * Overrides methods to keep keys in insertion order. Allows other methods in the superclass to work with ordered keys.
+ * </p>
+ *
+ * @see OrderedPropertiesFactory#INSTANCE
+ * @since 4.5
+ */
+public class OrderedProperties extends Properties {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * Preserves the insertion order.
+     */
+    private final LinkedHashSet<Object> orderedKeys = new LinkedHashSet<>();
+
+    @Override
+    public synchronized void clear() {
+        orderedKeys.clear();
+        super.clear();
+    }
+
+    @Override
+    public synchronized Object compute(Object key, BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
+        Object compute = super.compute(key, remappingFunction);
+        if (compute != null) {
+            orderedKeys.add(key);
+        }
+        return compute;
+    }
+
+    @Override
+    public synchronized Object computeIfAbsent(Object key, Function<? super Object, ? extends Object> mappingFunction) {
+        Object computeIfAbsent = super.computeIfAbsent(key, mappingFunction);
+        if (computeIfAbsent != null) {
+            orderedKeys.add(key);
+        }
+        return computeIfAbsent;
+    }
+
+    @Override
+    public synchronized Enumeration<Object> keys() {
+        return Collections.enumeration(orderedKeys);
+    }
+
+    @Override
+    public Set<Object> keySet() {
+        return orderedKeys;
+    }
+
+    @Override
+    public synchronized Object merge(final Object key, final Object value,
+            final BiFunction<? super Object, ? super Object, ? extends Object> remappingFunction) {
+        orderedKeys.add(key);
+        return super.merge(key, value, remappingFunction);
+    }
+
+    @Override
+    public Enumeration<?> propertyNames() {
+        return Collections.enumeration(orderedKeys);
+    }
+
+    @Override
+    public synchronized Object put(final Object key, final Object value) {
+        Object put = super.put(key, value);
+        if (put == null) {
+            orderedKeys.add(key);
+        }
+        return put;
+    }
+
+    @Override
+    public synchronized void putAll(final Map<? extends Object, ? extends Object> t) {
+        orderedKeys.addAll(t.keySet());
+        super.putAll(t);
+    }
+
+    @Override
+    public synchronized Object putIfAbsent(final Object key, final Object value) {
+        Object putIfAbsent = super.putIfAbsent(key, value);
+        if (putIfAbsent == null) {
+            orderedKeys.add(key);
+        }
+        return putIfAbsent;
+    }
+
+    @Override
+    public synchronized Object remove(final Object key) {
+        Object remove = super.remove(key);
+        if (remove != null) {
+            orderedKeys.remove(key);
+        }
+        return remove;
+    }
+
+    @Override
+    public synchronized boolean remove(final Object key, final Object value) {
+        boolean remove = super.remove(key, value);
+        if (remove) {
+            orderedKeys.remove(key);
+        }
+        return remove;
+    }
+}

src/main/java/org/apache/commons/collections4/properties/OrderedPropertiesFactory.java

@@ -0,0 +1,50 @@
+/*
+ * 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,
+ * 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.collections4.properties;
+
+/**
+ * Creates and loads {@link OrderedProperties}.
+ *
+ * @see OrderedProperties
+ * @since 4.5
+ */
+public class OrderedPropertiesFactory extends AbstractPropertiesFactory<OrderedProperties> {
+
+    /**
+     * The singleton instance.
+     */
+    public static final OrderedPropertiesFactory INSTANCE = new OrderedPropertiesFactory();
+
+    /**
+     * Constructs an instance.
+     */
+    private OrderedPropertiesFactory() {
+        // There is only one instance.
+    }
+
+    /**
+     * Subclasses override to provide customized properties instances.
+     *
+     * @return a new Properties instance.
+     */
+    @Override
+    protected OrderedProperties createProperties() {
+        return new OrderedProperties();
+    }
+
+}

src/test/java/org/apache/commons/collections4/properties/AbstractPropertiesFactoryTest.java

@@ -64,14 +64,14 @@ private void assertContents(final T properties) {
         assertEquals("value11", properties.getProperty("key11"));
     }
 
-    private boolean isXmlTest(final String fileExtension) {
-        return ".xml".equals(fileExtension);
-    }
-
     private String getPathString(final String fileExtension) {
         return BulkTest.TEST_PROPERTIES_PATH + "test" + fileExtension;
     }
 
+    private boolean isXmlTest(final String fileExtension) {
+        return ".xml".equals(fileExtension);
+    }
+
     @Test
     public void testInstance() {
         assertNotNull(PropertiesFactory.INSTANCE);

src/test/java/org/apache/commons/collections4/properties/OrderedPropertiesFactoryTest.java

@@ -0,0 +1,38 @@
+/*
+ * 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,
+ * 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.collections4.properties;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests {@link OrderedPropertiesFactory}.
+ */
+public class OrderedPropertiesFactoryTest extends AbstractPropertiesFactoryTest<OrderedProperties> {
+
+    public OrderedPropertiesFactoryTest() {
+        super(OrderedPropertiesFactory.INSTANCE);
+    }
+
+    @Test
+    @Override
+    public void testInstance() {
+        assertNotNull(OrderedPropertiesFactory.INSTANCE);
+    }
+
+}