[IO-632] Add PathUtils for operations on NIO Path.

Author: Gary Gregory

src/changes/changes.xml

@@ -146,6 +146,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action issue="IO-631" dev="ggregory" type="add" due-to="Gary Gregory">
         Add a CountingFileVisitor (as the basis for a forthcoming DeletingFileVisitor).
       </action>
+      <action issue="IO-632" dev="ggregory" type="add" due-to="Gary Gregory">
+        Add PathUtils for operations on NIO Path.
+      </action>
     </release>
 
     <release version="2.6" date="2017-10-15" description="Java 7 required, Java 9 supported.">

src/main/java/org/apache/commons/io/PathUtils.java

@@ -0,0 +1,70 @@
+/*
+ * 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.io;
+
+import java.io.IOException;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * NIO Path utilities.
+ *
+ * @since 2.7
+ */
+public class PathUtils {
+
+    /**
+     * Returns whether the given file or directory is empty.
+     *
+     * @param path the the given file or directory to query.
+     * @return whether the given file or directory is empty.
+     * @throws IOException if an I/O error occurs
+     */
+    public static boolean isEmpty(final Path path) throws IOException {
+        return Files.isDirectory(path) ? isEmptyDirectory(path) : isEmptyFile(path);
+    }
+
+    /**
+     * Returns whether the directory is empty.
+     *
+     * @param directory the the given directory to query.
+     * @return whether the given directory is empty.
+     * @throws IOException if an I/O error occurs
+     */
+    public static boolean isEmptyDirectory(final Path directory) throws IOException {
+        try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(directory)) {
+            if (directoryStream.iterator().hasNext()) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Returns whether the given file is empty.
+     *
+     * @param file the the given file to query.
+     * @return whether the given file is empty.
+     * @throws IOException if an I/O error occurs
+     */
+    public static boolean isEmptyFile(final Path file) throws IOException {
+        return Files.size(file) <= 0;
+    }
+
+}

src/test/java/org/apache/commons/io/PathUtilsTest.java

@@ -0,0 +1,70 @@
+/*
+ * 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.io;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests {@link PathUtils}.
+ */
+public class PathUtilsTest {
+
+    private static final Path DIR_SIZE_1 = Paths.get("src/test/resources/org/apache/commons/io/dirs-1-file-size-1");
+
+    private static final Path FILE_SIZE_0 = Paths
+            .get("src/test/resources/org/apache/commons/io/dirs-1-file-size-0/file-size-0.bin");
+
+    private static final Path FILE_SIZE_1 = Paths
+            .get("src/test/resources/org/apache/commons/io/dirs-1-file-size-1/file-size-1.bin");
+
+    @Test
+    public void testIsEmpty() throws IOException {
+        Assertions.assertTrue(PathUtils.isEmpty(FILE_SIZE_0));
+        Assertions.assertFalse(PathUtils.isEmpty(FILE_SIZE_1));
+        final Path tempDirectory = Files.createTempDirectory(getClass().getCanonicalName());
+        try {
+            Assertions.assertTrue(PathUtils.isEmpty(tempDirectory));
+        } finally {
+            Files.delete(tempDirectory);
+        }
+        Assertions.assertFalse(PathUtils.isEmpty(DIR_SIZE_1));
+    }
+
+    @Test
+    public void testisEmptyDirectory() throws IOException {
+        final Path tempDirectory = Files.createTempDirectory(getClass().getCanonicalName());
+        try {
+            Assertions.assertTrue(PathUtils.isEmptyDirectory(tempDirectory));
+        } finally {
+            Files.delete(tempDirectory);
+        }
+        Assertions.assertFalse(PathUtils.isEmptyDirectory(DIR_SIZE_1));
+    }
+
+    @Test
+    public void testisEmptyFile() throws IOException {
+        Assertions.assertTrue(PathUtils.isEmptyFile(FILE_SIZE_0));
+        Assertions.assertFalse(PathUtils.isEmptyFile(FILE_SIZE_1));
+    }
+}