better preferences file management (detected during PROBLEM-2297)

SalsaUtils/src/main/java/fr/soleil/salsa/preferences/DevicePreferencesPersistence.java

@@ -5,10 +5,10 @@ import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
+import java.text.Collator;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.TreeMap;
 
 import javax.xml.XMLConstants;
 import javax.xml.parsers.DocumentBuilder;
@@ -45,9 +45,12 @@ public class DevicePreferencesPersistence {
     /** scanserver device property name */
     public static final String SCANSERVER_PROPERTY = "SCANSERVER";
 
-    private static final DevicePreferences DEVICE_PREFERENCES;
-    static {
-        DevicePreferences devicePreferences = null;
+    private static DevicePreferences devicePreferences = null;
+    private static final Object DEVICE_PREFERENCES_LOCK = new Object();
+
+    public static DevicePreferences getSystemPreferences() {
+        if (devicePreferences == null) {
+            synchronized (DEVICE_PREFERENCES_LOCK) {
                 if (devicePreferences == null) {
                     String preferencePath = SystemUtils.getSystemProperty(PREFERENCE_FILE_PROPERTY);
                     if ((preferencePath == null) || preferencePath.trim().isEmpty()) {
@@ -57,11 +60,9 @@ public class DevicePreferencesPersistence {
                         devicePreferences = load(preferencePath, scanServer);
                     }
                 }
-        DEVICE_PREFERENCES = devicePreferences;
             }
-
-    public static DevicePreferences getSystemPreferences() {
-        return DEVICE_PREFERENCES;
+        }
+        return devicePreferences;
     }
 
     private static String getDefaultScanServer() {
@@ -146,8 +147,7 @@ public class DevicePreferencesPersistence {
     /**
      * Save preferences on file system.
      * 
-     * @param devicePreferences
-     *            The preferences to save
+     * @param devicePreferences The preferences to save.
      */
     public static void save(DevicePreferences devicePreferences) {
         if (devicePreferences != null) {
@@ -162,30 +162,28 @@ public class DevicePreferencesPersistence {
 
                 document.appendChild(root);
 
-                HashMap<String, String> hashMap = new HashMap<>();
-
-                hashMap.put(PreferenceItem.DataFitter.name(), devicePreferences.getDataFitter());
-                hashMap.put(PreferenceItem.DataRecorder.name(), String.valueOf(devicePreferences.isDataRecorder()));
-                hashMap.put(PreferenceItem.ScanServer.name(), devicePreferences.getScanServer());
-                hashMap.put(PreferenceItem.UserLogFile.name(), devicePreferences.getUserLogFile());
-                hashMap.put(PreferenceItem.Publisher.name(), devicePreferences.getPublisher());
+                Map<String, String> preferenceMap = new TreeMap<>(Collator.getInstance());
+                preferenceMap.put(PreferenceItem.DataFitter.name(), devicePreferences.getDataFitter());
+                preferenceMap.put(PreferenceItem.DataRecorder.name(),
+                        String.valueOf(devicePreferences.isDataRecorder()));
+                preferenceMap.put(PreferenceItem.ScanServer.name(), devicePreferences.getScanServer());
+                preferenceMap.put(PreferenceItem.UserLogFile.name(), devicePreferences.getUserLogFile());
+                preferenceMap.put(PreferenceItem.Publisher.name(), devicePreferences.getPublisher());
                 Integer maxLineNumber = devicePreferences.getMaxLineNumber();
-                hashMap.put(PreferenceItem.MaxLineNumber.name(),
+                preferenceMap.put(PreferenceItem.MaxLineNumber.name(),
                         maxLineNumber != null ? maxLineNumber.toString() : ObjectUtils.EMPTY_STRING);
-                hashMap.put(PreferenceItem.RecordingManager.name(), devicePreferences.getRecordingManager());
-                hashMap.put(PreferenceItem.RecordingManagerProfil.name(),
+                preferenceMap.put(PreferenceItem.RecordingManager.name(), devicePreferences.getRecordingManager());
+                preferenceMap.put(PreferenceItem.RecordingManagerProfil.name(),
                         devicePreferences.getRecordingManagerProfil());
-
-                List<String> keys = new ArrayList<>(hashMap.keySet());
-                Collections.sort(keys, null);
-                for (String key : keys) {
-                    String value = hashMap.get(key);
+                for (Entry<String, String> entry : preferenceMap.entrySet()) {
+                    String key = entry.getKey();
+                    String value = entry.getValue();
                     Element e = document.createElement("add");
                     e.setAttribute("key", key);
                     e.setTextContent(value);
                     root.appendChild(e);
                 }
-                hashMap.clear();
+                preferenceMap.clear();
 
                 String str = XMLUtils.xmlToString(document);
                 File f = new File(devicePreferences.getPreferenceFile());