Merge pull request #209 from spdx/fixsonar

Fix issues identified by Sonar

Author: goneall

src/main/java/org/spdx/utility/DownloadCache.java

@@ -134,29 +134,26 @@ public static DownloadCache getInstance() {
      * Recursively removes a directory. USE WITH CAUTION!
      *
      * @param dir The directory to delete.
+     * @throws IOException 
      */
-    private static void rmdir(final File dir) {
-        if (dir != null && dir.exists() && dir.isDirectory()) {
-            File[] contents = dir.listFiles();
-            if (contents != null) {
-                for (final File f : contents) {
-                    if (f.isDirectory()) {
-                        rmdir(f);
-                    } else {
-                        f.delete();
-                    }
-                }
-            }
-            dir.delete();
-        }
+    private static void rmdir(final File dir) throws IOException {
+    	if (Objects.isNull(dir) || !dir.exists()) {
+    		return;
+    	}
+    	File[] contents = dir.listFiles();
+    	if (Objects.nonNull(contents)) {
+    		for (final File f : contents) {
+    			rmdir(f);
+    		}
+    	}
+    	Files.delete(dir.toPath());
     }
 
     /**
      * Resets (deletes) the local cache.
      */
     public void resetCache() throws IOException {
         final File cacheDirectory = new File(cacheDir);
-
         rmdir(cacheDirectory);
         Files.createDirectories(cacheDirectory.toPath());
     }
@@ -400,12 +397,9 @@ private HashMap<String,String> readMetadataFile(final File metadataFile) {
      * @throws IOException When an IO error of some kind occurs.
      */
     private void writeMetadataFile(final File metadataFile, HashMap<String,String> metadata) throws IOException {
-        final Writer w = new BufferedWriter(new FileWriter(metadataFile));
-        try {
+        try (final Writer w = new BufferedWriter(new FileWriter(metadataFile))) {
             new Gson().toJson(metadata, new TypeToken<HashMap<String, String>>(){}.getType(), w);
-        } finally {
             w.flush();
-            w.close();
         }
     }
 
@@ -417,18 +411,15 @@ private void writeMetadataFile(final File metadataFile, HashMap<String,String> m
      * @throws IOException When an IO error of some kind occurs.
      */
     private void writeContentFile(final InputStream is, final File cachedFile) throws IOException {
-        final OutputStream cacheFileOutputStream = new BufferedOutputStream(new FileOutputStream(cachedFile));
-        try {
-            byte[] ioBuffer = new byte[IO_BUFFER_SIZE];
+    	try (final OutputStream cacheFileOutputStream = new BufferedOutputStream(new FileOutputStream(cachedFile))) {
+    		byte[] ioBuffer = new byte[IO_BUFFER_SIZE];
             int length;
             while ((length = is.read(ioBuffer)) != -1) {
                 cacheFileOutputStream.write(ioBuffer, 0, length);
             }
-        } finally {
-            is.close();
             cacheFileOutputStream.flush();
-            cacheFileOutputStream.close();
-        }
+    	}
+    	is.close();
     }
 
     /**